//-----------------------------------------------------------------------------
// Copyright (C) Jonathan Westhues, Nov 2006
// Copyright (C) Greg Jones, Jan 2009
// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// See LICENSE.txt for the text of the license.
//-----------------------------------------------------------------------------
// Routines to support ISO 15693. This includes both the reader software and
// the `fake tag' modes.
//-----------------------------------------------------------------------------

// The ISO 15693 describes two transmission modes from reader to tag, and four
// transmission modes from tag to reader. As of Oct 2018 this code supports
// both reader modes and the high speed variant with one subcarrier from card to reader.
// As long as the card fully support ISO 15693 this is no problem, since the
// reader chooses both data rates, but some non-standard tags do not.
// For card simulation, the code supports both high and low speed modes with one subcarrier.
//
// VCD (reader) -> VICC (tag)
// 1 out of 256:
//  data rate: 1,66 kbit/s (fc/8192)
//  used for long range
// 1 out of 4:
//  data rate: 26,48 kbit/s (fc/512)
//  used for short range, high speed
//
// VICC (tag) -> VCD (reader)
// Modulation:
//    ASK / one subcarrier (423,75 kHz)
//    FSK / two subcarriers (423,75 kHz && 484,28 kHz)
// Data Rates / Modes:
//  low ASK: 6,62 kbit/s
//  low FSK: 6.67 kbit/s
//  high ASK: 26,48 kbit/s
//  high FSK: 26,69 kbit/s
//-----------------------------------------------------------------------------
// added "1 out of 256" mode (for VCD->PICC) - atrox 20100911


// Random Remarks:
// *) UID is always used "transmission order" (LSB), which is reverse to display order

// TODO / BUGS / ISSUES:
// *) signal decoding is unable to detect collisions.
// *) add anti-collision support for inventory-commands
// *) read security status of a block
// *) simulation do not support two subcarrier modes.
// *) remove or refactor code under "deprecated"
// *) document all the functions

#include "iso15693.h"

#include "proxmark3_arm.h"
#include "util.h"
#include "string.h"
#include "iso15693tools.h"
#include "protocols.h"
#include "cmd.h"
#include "appmain.h"
#include "dbprint.h"
#include "fpgaloader.h"
#include "commonutil.h"
#include "ticks.h"
#include "BigBuf.h"
#include "crc16.h"

// Delays in SSP_CLK ticks.
// SSP_CLK runs at 13,56MHz / 32 = 423.75kHz when simulating a tag
#define DELAY_READER_TO_ARM               8
#define DELAY_ARM_TO_READER               0

//SSP_CLK runs at 13.56MHz / 4 = 3,39MHz when acting as reader. All values should be multiples of 16
#define DELAY_ARM_TO_TAG                 16
#define DELAY_TAG_TO_ARM                 32

//SSP_CLK runs at 13.56MHz / 4 = 3,39MHz when sniffing. All values should be multiples of 16
#define DELAY_TAG_TO_ARM_SNIFF           32
#define DELAY_READER_TO_ARM_SNIFF        32

// times in samples @ 212kHz when acting as reader
#define ISO15693_READER_TIMEOUT            330  // 330/212kHz = 1558us
#define ISO15693_READER_TIMEOUT_WRITE      4700 // 4700/212kHz = 22ms, nominal 20ms

// iceman: This defines below exists in the header file,  just here for my easy reading
// Delays in SSP_CLK ticks.
// SSP_CLK runs at 13,56MHz / 32 = 423.75kHz when simulating a tag
//#define DELAY_ISO15693_VCD_TO_VICC_SIM     132  // 132/423.75kHz = 311.5us from end of command EOF to start of tag response

//SSP_CLK runs at 13.56MHz / 4 = 3,39MHz when acting as reader. All values should be multiples of 16
//#define DELAY_ISO15693_VCD_TO_VICC_READER 1056 // 1056/3,39MHz = 311.5us from end of command EOF to start of tag response
//#define DELAY_ISO15693_VICC_TO_VCD_READER 1024 // 1024/3.39MHz = 302.1us between end of tag response and next reader command


///////////////////////////////////////////////////////////////////////
// ISO 15693 Part 2 - Air Interface
// This section basically contains transmission and receiving of bits
///////////////////////////////////////////////////////////////////////

// buffers
#define ISO15693_MAX_RESPONSE_LENGTH     2116 // allows read multiple block with the maximum block size of 256bits and a maximum block number of 64 with REQ_OPTION (lock status for each block).
#define ISO15693_MAX_COMMAND_LENGTH      45 // allows write single block with the maximum block size of 256bits. Write multiple blocks not supported yet

// 32 + 2 crc + 1
#define ISO15_MAX_FRAME     35
#define CMD_ID_RESP         5
#define CMD_READ_RESP       13
#define CMD_INV_RESP        12
#define CMD_SYSINFO_RESP    17

//#define Crc(data, len)        Crc(CRC_15693, (data), (len))
#define CheckCrc15(data, len)   check_crc(CRC_15693, (data), (len))
#define AddCrc15(data, len)     compute_crc(CRC_15693, (data), (len), (data)+(len), (data)+(len)+1)
#define CalculateCrc15(data, len)  Crc16ex(CRC_15693, (data), (len))

static void BuildIdentifyRequest(uint8_t *cmd);

// ---------------------------

// Signal Processing
// ---------------------------

// prepare data using "1 out of 4" code for later transmission
// resulting data rate is 26.48 kbit/s (fc/512)
// cmd ... data
// n ... length of data
static uint8_t encode15_lut[] = {
    0x40, // 01000000
    0x10, // 00010000
    0x04, // 00000100
    0x01  // 00000001
};

void CodeIso15693AsReader(const uint8_t *cmd, int n) {

    tosend_reset();
    tosend_t *ts = get_tosend();

    // SOF for 1of4
    ts->buf[++ts->max] = 0x84; //10000100

    // data
    for (int i = 0; i < n; i++) {

        volatile uint8_t b = (cmd[i] >> 0) & 0x03;
        ts->buf[++ts->max] = encode15_lut[b];

        b = (cmd[i] >> 2) & 0x03;
        ts->buf[++ts->max] = encode15_lut[b];

        b = (cmd[i] >> 4) & 0x03;
        ts->buf[++ts->max] = encode15_lut[b];

        b = (cmd[i] >> 6) & 0x03;
        ts->buf[++ts->max] = encode15_lut[b];
    }

    // EOF
    ts->buf[++ts->max] = 0x20; //0010 + 0000 padding
    ts->max++;
}

// Encode EOF only
static void CodeIso15693AsReaderEOF(void) {
    tosend_reset();
    tosend_t *ts = get_tosend();
    ts->buf[++ts->max] = 0x20;
    ts->max++;
}


static int get_uid_slix(uint32_t start_time, uint32_t *eof_time, uint8_t *uid) {

    uint8_t *answer = BigBuf_malloc(ISO15693_MAX_RESPONSE_LENGTH);
    memset(answer, 0x00, ISO15693_MAX_RESPONSE_LENGTH);

    start_time = *eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;

    uint8_t cmd[5] = {0};
    BuildIdentifyRequest(cmd);
    uint16_t recvlen = 0;
    SendDataTag(cmd, sizeof(cmd), false, true, answer, ISO15693_MAX_RESPONSE_LENGTH, start_time, ISO15693_READER_TIMEOUT, eof_time, &recvlen);

    if (recvlen != 12) {
        return PM3_ETIMEOUT;
    }

    uid[0] = answer[2];
    uid[1] = answer[3];
    uid[2] = answer[4];
    uid[3] = answer[5];
    uid[4] = answer[6];
    uid[5] = answer[7];
    uid[6] = answer[8];
    uid[7] = answer[9];

    BigBuf_free();
    return PM3_SUCCESS;
}


// encode data using "1 out of 256" scheme
// data rate is 1,66 kbit/s (fc/8192)
// is designed for more robust communication over longer distances
static void CodeIso15693AsReader256(const uint8_t *cmd, int n) {

    tosend_reset();
    tosend_t *ts = get_tosend();

    // SOF for 1of256
    ts->buf[++ts->max] = 0x81; //10000001

    // data
    for (int i = 0; i < n; i++) {
        for (int j = 0; j <= 255; j++) {
            if (cmd[i] == j) {
                tosend_stuffbit(0);
                tosend_stuffbit(1);
            } else {
                tosend_stuffbit(0);
                tosend_stuffbit(0);
            }
        }
    }

    // EOF
    ts->buf[++ts->max] = 0x20; //0010 + 0000 padding
    ts->max++;
}

static const uint8_t encode_4bits[16] = {
//  0     1     2     3
    0xaa, 0x6a, 0x9a, 0x5a,
//  4     5     6     7
    0xa6, 0x66, 0x96, 0x56,
//  8     9     A     B
    0xa9, 0x69, 0x99, 0x59,
//  C    D      E     F
    0xa5, 0x65, 0x95, 0x55
};

void CodeIso15693AsTag(const uint8_t *cmd, size_t len) {
    /*
     * SOF comprises 3 parts;
     * * An unmodulated time of 56.64 us
     * * 24 pulses of 423.75 kHz (fc/32)
     * * A logic 1, which starts with an unmodulated time of 18.88us
     *   followed by 8 pulses of 423.75kHz (fc/32)
     *
     * EOF comprises 3 parts:
     * - A logic 0 (which starts with 8 pulses of fc/32 followed by an unmodulated
     *   time of 18.88us.
     * - 24 pulses of fc/32
     * - An unmodulated time of 56.64 us
     *
     * A logic 0 starts with 8 pulses of fc/32
     * followed by an unmodulated time of 256/fc (~18,88us).
     *
     * A logic 0 starts with unmodulated time of 256/fc (~18,88us) followed by
     * 8 pulses of fc/32 (also 18.88us)
     *
     * A bit here becomes 8 pulses of fc/32. Therefore:
     * The SOF can be written as 00011101 = 0x1D
     * The EOF can be written as 10111000 = 0xb8
     * A logic 1 is 01
     * A logic 0 is 10
     *
     * */
    tosend_reset();
    tosend_t *ts = get_tosend();

    // SOF
    ts->buf[++ts->max] = 0x1D;  // 00011101

    // data
    for (size_t i = 0; i < len; i ++) {
        ts->buf[++ts->max] = encode_4bits[cmd[i] & 0xF];
        ts->buf[++ts->max] = encode_4bits[cmd[i] >> 4];
    }

    // EOF
    ts->buf[++ts->max] = 0xB8; // 10111000
    ts->max++;
}

// Transmit the command (to the tag) that was placed in cmd[].
void TransmitTo15693Tag(const uint8_t *cmd, int len, uint32_t *start_time, bool shallow_mod) {

#ifdef RDV4
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | (shallow_mod ? FPGA_HF_READER_MODE_SEND_SHALLOW_MOD_RDV4 : FPGA_HF_READER_MODE_SEND_FULL_MOD));
#else
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | (shallow_mod ? FPGA_HF_READER_MODE_SEND_SHALLOW_MOD : FPGA_HF_READER_MODE_SEND_FULL_MOD));
#endif


    if (*start_time < DELAY_ARM_TO_TAG) {
        *start_time = DELAY_ARM_TO_TAG;
    }

    *start_time = (*start_time - DELAY_ARM_TO_TAG) & 0xfffffff0;

    if (GetCountSspClk() > *start_time) { // we may miss the intended time
        *start_time = (GetCountSspClk() + 16) & 0xfffffff0; // next possible time
    }

    // wait
    while (GetCountSspClk() < *start_time) ;

    LED_B_ON();
    for (int c = 0; c < len; c++) {
        volatile uint8_t data = cmd[c];

        for (uint8_t i = 0; i < 8; i++) {
            uint16_t send_word = (data & 0x80) ? 0xffff : 0x0000;
            while (!(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY))) ;
            AT91C_BASE_SSC->SSC_THR = send_word;
            while (!(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY))) ;
            AT91C_BASE_SSC->SSC_THR = send_word;
            data <<= 1;
        }
        WDT_HIT();
    }
    LED_B_OFF();

    *start_time = *start_time + DELAY_ARM_TO_TAG;
    FpgaDisableTracing();
}

//-----------------------------------------------------------------------------
// Transmit the tag response (to the reader) that was placed in cmd[].
//-----------------------------------------------------------------------------
void TransmitTo15693Reader(const uint8_t *cmd, size_t len, uint32_t *start_time, uint32_t slot_time, bool slow) {

    // don't use the FPGA_HF_SIMULATOR_MODULATE_424K_8BIT minor mode. It would spoil GetCountSspClk()
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_424K);

    uint32_t modulation_start_time = *start_time - DELAY_ARM_TO_READER + 3 * 8;  // no need to transfer the unmodulated start of SOF

    while (GetCountSspClk() > (modulation_start_time & 0xfffffff8) + 3) { // we will miss the intended time
        if (slot_time) {
            modulation_start_time += slot_time; // use next available slot
        } else {
            modulation_start_time = (modulation_start_time & 0xfffffff8) + 8; // next possible time
        }
    }

    // wait
    while (GetCountSspClk() < (modulation_start_time & 0xfffffff8)) ;

    uint8_t shift_delay = modulation_start_time & 0x00000007;

    *start_time = modulation_start_time + DELAY_ARM_TO_READER - 3 * 8;

    LED_C_ON();
    uint8_t bits_to_shift = 0x00;
    uint8_t bits_to_send = 0x00;

    for (size_t c = 0; c < len; c++) {
        for (int i = (c == 0 ? 4 : 7); i >= 0; i--) {

            uint8_t cmd_bits = ((cmd[c] >> i) & 0x01) ? 0xff : 0x00;

            for (int j = 0; j < (slow ? 4 : 1);) {
                if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
                    bits_to_send = bits_to_shift << (8 - shift_delay) | cmd_bits >> shift_delay;
                    AT91C_BASE_SSC->SSC_THR = bits_to_send;
                    bits_to_shift = cmd_bits;
                    j++;
                }
            }
        }
        WDT_HIT();
    }

    // send the remaining bits, padded with 0:
    bits_to_send = bits_to_shift << (8 - shift_delay);
    if (bits_to_send) {
        for (; ;) {
            if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
                AT91C_BASE_SSC->SSC_THR = bits_to_send;
                break;
            }
        }
    }
    LED_C_OFF();
}

//=============================================================================
// An ISO 15693 decoder for tag responses (one subcarrier only).
// Uses cross correlation to identify each bit and EOF.
// This function is called 8 times per bit (every 2 subcarrier cycles).
// Subcarrier frequency fs is 424kHz, 1/fs = 2,36us,
// i.e. function is called every 4,72us
// LED handling:
//    LED C -> ON once we have received the SOF and are expecting the rest.
//    LED C -> OFF once we have received EOF or are unsynced
//
// Returns: true if we received a EOF
//          false if we are still waiting for some more
//=============================================================================

#define NOISE_THRESHOLD          80                   // don't try to correlate noise
#define MAX_PREVIOUS_AMPLITUDE   (-1 - NOISE_THRESHOLD)

typedef struct {
    enum {
        STATE_TAG_SOF_LOW,
        STATE_TAG_SOF_RISING_EDGE,
        STATE_TAG_SOF_HIGH,
        STATE_TAG_SOF_HIGH_END,
        STATE_TAG_RECEIVING_DATA,
        STATE_TAG_EOF,
        STATE_TAG_EOF_TAIL
    } state;
    int bitCount;
    int posCount;
    enum {
        LOGIC0,
        LOGIC1,
        SOF_PART1,
        SOF_PART2
    } lastBit;
    uint16_t shiftReg;
    uint16_t max_len;
    uint16_t len;
    int sum1;
    int sum2;
    int threshold_sof;
    int threshold_half;
    uint16_t previous_amplitude;
    uint8_t *output;
} DecodeTag_t;

//-----------------------------------------------------------------------------
// DEMODULATE tag answer
//-----------------------------------------------------------------------------
static RAMFUNC int Handle15693SamplesFromTag(uint16_t amplitude, DecodeTag_t *tag, bool recv_speed) {

    switch (tag->state) {

        case STATE_TAG_SOF_LOW: {
            // waiting for a rising edge
            if (amplitude > NOISE_THRESHOLD + tag->previous_amplitude) {
                if (tag->posCount > 10) {
                    tag->threshold_sof = amplitude - tag->previous_amplitude; // to be divided by 2
                    tag->threshold_half = 0;
                    tag->state = STATE_TAG_SOF_RISING_EDGE;
                } else {
                    tag->posCount = 0;
                }
            } else {
                tag->posCount++;
                tag->previous_amplitude = amplitude;
            }
            break;
        }

        case STATE_TAG_SOF_RISING_EDGE: {
            if (amplitude > tag->threshold_sof + tag->previous_amplitude) { // edge still rising
                if (amplitude > tag->threshold_sof + tag->threshold_sof) { // steeper edge, take this as time reference
                    tag->posCount = 1;
                } else {
                    tag->posCount = 2;
                }
                tag->threshold_sof = (amplitude - tag->previous_amplitude) / 2;
            } else {
                tag->posCount = 2;
                tag->threshold_sof = tag->threshold_sof / 2;
            }
            tag->state = STATE_TAG_SOF_HIGH;
            break;
        }

        case STATE_TAG_SOF_HIGH: {
            // waiting for 10 times high. Take average over the last 8
            if (amplitude > tag->threshold_sof) {
                tag->posCount++;
                if (tag->posCount > 2) {
                    tag->threshold_half += amplitude; // keep track of average high value
                }
                if (tag->posCount == (recv_speed ? 10 : 40)) {
                    tag->threshold_half >>= 2; // (4 times 1/2 average)
                    tag->state = STATE_TAG_SOF_HIGH_END;
                }
            } else { // high phase was too short
                tag->posCount = 1;
                tag->previous_amplitude = amplitude;
                tag->state = STATE_TAG_SOF_LOW;
            }
            break;
        }

        case STATE_TAG_SOF_HIGH_END: {
            // check for falling edge
            if (tag->posCount == (recv_speed ? 13 : 52) && amplitude < tag->threshold_sof) {
                tag->lastBit = SOF_PART1;  // detected 1st part of SOF (12 samples low and 12 samples high)
                tag->shiftReg = 0;
                tag->bitCount = 0;
                tag->len = 0;
                tag->sum1 = amplitude;
                tag->sum2 = 0;
                tag->posCount = 2;
                tag->state = STATE_TAG_RECEIVING_DATA;
                LED_C_ON();
            } else {
                tag->posCount++;
                if (tag->posCount > (recv_speed ? 13 : 52)) { // high phase too long
                    tag->posCount = 0;
                    tag->previous_amplitude = amplitude;
                    tag->state = STATE_TAG_SOF_LOW;
                    LED_C_OFF();
                }
            }
            break;
        }

        case STATE_TAG_RECEIVING_DATA: {
            if (tag->posCount == 1) {
                tag->sum1 = 0;
                tag->sum2 = 0;
            }

            if (tag->posCount <= (recv_speed ? 4 : 16)) {
                tag->sum1 += amplitude;
            } else {
                tag->sum2 += amplitude;
            }

            if (tag->posCount == (recv_speed ? 8 : 32)) {
                if (tag->sum1 > tag->threshold_half && tag->sum2 > tag->threshold_half) { // modulation in both halves
                    if (tag->lastBit == LOGIC0) {  // this was already part of EOF
                        tag->state = STATE_TAG_EOF;
                    } else {
                        tag->posCount = 0;
                        tag->previous_amplitude = amplitude;
                        tag->state = STATE_TAG_SOF_LOW;
                        LED_C_OFF();
                    }
                } else if (tag->sum1 < tag->threshold_half && tag->sum2 > tag->threshold_half) { // modulation in second half
                    // logic 1
                    if (tag->lastBit == SOF_PART1) { // still part of SOF
                        tag->lastBit = SOF_PART2;    // SOF completed
                    } else {
                        tag->lastBit = LOGIC1;
                        tag->shiftReg >>= 1;
                        tag->shiftReg |= 0x80;
                        tag->bitCount++;
                        if (tag->bitCount == 8) {
                            tag->output[tag->len] = tag->shiftReg & 0xFF;
                            tag->len++;

                            if (tag->len > tag->max_len) {
                                // buffer overflow, give up
                                LED_C_OFF();
                                return true;
                            }
                            tag->bitCount = 0;
                            tag->shiftReg = 0;
                        }
                    }
                } else if (tag->sum1 > tag->threshold_half && tag->sum2 < tag->threshold_half) { // modulation in first half
                    // logic 0
                    if (tag->lastBit == SOF_PART1) { // incomplete SOF
                        tag->posCount = 0;
                        tag->previous_amplitude = amplitude;
                        tag->state = STATE_TAG_SOF_LOW;
                        LED_C_OFF();
                    } else {
                        tag->lastBit = LOGIC0;
                        tag->shiftReg >>= 1;
                        tag->bitCount++;

                        if (tag->bitCount == 8) {
                            tag->output[tag->len] = (tag->shiftReg & 0xFF);
                            tag->len++;

                            if (tag->len > tag->max_len) {
                                // buffer overflow, give up
                                tag->posCount = 0;
                                tag->previous_amplitude = amplitude;
                                tag->state = STATE_TAG_SOF_LOW;
                                LED_C_OFF();
                            }
                            tag->bitCount = 0;
                            tag->shiftReg = 0;
                        }
                    }
                } else { // no modulation
                    if (tag->lastBit == SOF_PART2) { // only SOF (this is OK for iClass)
                        LED_C_OFF();
                        return true;
                    } else {
                        tag->posCount = 0;
                        tag->state = STATE_TAG_SOF_LOW;
                        LED_C_OFF();
                    }
                }
                tag->posCount = 0;
            }
            tag->posCount++;
            break;
        }

        case STATE_TAG_EOF: {
            if (tag->posCount == 1) {
                tag->sum1 = 0;
                tag->sum2 = 0;
            }

            if (tag->posCount <= (recv_speed ? 4 : 16)) {
                tag->sum1 += amplitude;
            } else {
                tag->sum2 += amplitude;
            }

            if (tag->posCount == (recv_speed ? 8 : 32)) {
                if (tag->sum1 > tag->threshold_half && tag->sum2 < tag->threshold_half) { // modulation in first half
                    tag->posCount = 0;
                    tag->state = STATE_TAG_EOF_TAIL;
                } else {
                    tag->posCount = 0;
                    tag->previous_amplitude = amplitude;
                    tag->state = STATE_TAG_SOF_LOW;
                    LED_C_OFF();
                }
            }
            tag->posCount++;
            break;
        }

        case STATE_TAG_EOF_TAIL: {
            if (tag->posCount == 1) {
                tag->sum1 = 0;
                tag->sum2 = 0;
            }

            if (tag->posCount <= (recv_speed ? 4 : 16)) {
                tag->sum1 += amplitude;
            } else {
                tag->sum2 += amplitude;
            }

            if (tag->posCount == (recv_speed ? 8 : 32)) {
                if (tag->sum1 < tag->threshold_half && tag->sum2 < tag->threshold_half) { // no modulation in both halves
                    LED_C_OFF();
                    return true;
                } else {
                    tag->posCount = 0;
                    tag->previous_amplitude = amplitude;
                    tag->state = STATE_TAG_SOF_LOW;
                    LED_C_OFF();
                }
            }
            tag->posCount++;
            break;
        }
    }

    return false;
}

static void DecodeTagReset(DecodeTag_t *tag) {
    tag->posCount = 0;
    tag->state = STATE_TAG_SOF_LOW;
    tag->previous_amplitude = MAX_PREVIOUS_AMPLITUDE;
}

static void DecodeTagInit(DecodeTag_t *tag, uint8_t *data, uint16_t max_len) {
    tag->output = data;
    tag->max_len = max_len;
    DecodeTagReset(tag);
}

//=============================================================================
// An ISO 15693 decoder for tag responses in FSK (two subcarriers) mode.
// Subcarriers frequencies are 424kHz and 484kHz (fc/32 and fc/28),
// LED handling:
//    LED C -> ON once we have received the SOF and are expecting the rest.
//    LED C -> OFF once we have received EOF or are unsynced
//
// Returns: true if we received a EOF
//          false if we are still waiting for some more
//=============================================================================
//#define DEBUG 1
#define FREQ_IS_484(f)    ((f & 1) == 1)   //(f >= 26 && f <= 30)
#define FREQ_IS_424(f)    ((f & 2) == 2)   //(f >= 30 && f <= 34)
#define FREQ_IS_0(f)      ((f & 3) == 0)   // (f <= 24 || f >= 36)
#define SEOF_COUNT(c, s)  ((s) ? (c >= 11 && c <= 13) : (c >= 45 && c <= 51))
#define LOGIC_COUNT(c, s) ((s) ? (c >= 3 && c <= 6) : (c >= 14 && c <= 20))
#define MAX_COUNT(c, s)   ((s) ? (c >= 13) : (c >= 52))

typedef struct DecodeTagFSK {
    enum {
        STATE_FSK_ERROR,
        STATE_FSK_BEFORE_SOF,
        STATE_FSK_SOF_484,
        STATE_FSK_SOF_424,
        STATE_FSK_SOF_END_484,
        STATE_FSK_SOF_END_424,
        STATE_FSK_RECEIVING_DATA_484,
        STATE_FSK_RECEIVING_DATA_424,
        STATE_FSK_EOF
    }        state;
    enum {
        LOGIC0_PART1,
        LOGIC1_PART1,
        LOGIC0_PART2,
        LOGIC1_PART2,
        SOF
    }        lastBit;
    uint8_t  count;
    uint8_t  bitCount;
    uint8_t  shiftReg;
    uint16_t len;
    uint16_t max_len;
    uint8_t  *output;
} DecodeTagFSK_t;

static void DecodeTagFSKReset(DecodeTagFSK_t *DecodeTag) {
    DecodeTag->state = STATE_FSK_BEFORE_SOF;
    DecodeTag->bitCount = 0;
    DecodeTag->len = 0;
    DecodeTag->shiftReg = 0;
}

static void DecodeTagFSKInit(DecodeTagFSK_t *DecodeTag, uint8_t *data, uint16_t max_len) {
    DecodeTag->output = data;
    DecodeTag->max_len = max_len;
    DecodeTagFSKReset(DecodeTag);
}

// Performances of this function are crutial for stability
// as it is called in real time for every samples
static int RAMFUNC Handle15693FSKSamplesFromTag(uint8_t freq, DecodeTagFSK_t *DecodeTag, bool recv_speed) {
    switch (DecodeTag->state) {
        case STATE_FSK_BEFORE_SOF:
            if (FREQ_IS_484(freq)) {
                // possible SOF starting
                DecodeTag->state = STATE_FSK_SOF_484;
                DecodeTag->lastBit = LOGIC0_PART1;
                DecodeTag->count = 1;
            }
            break;

        case STATE_FSK_SOF_484:
            //DbpString("STATE_FSK_SOF_484");
            if (FREQ_IS_424(freq) && SEOF_COUNT(DecodeTag->count, recv_speed)) {
                // SOF part1 continue at 424
                DecodeTag->state = STATE_FSK_SOF_424;
                DecodeTag->count = 1;
            } else if (FREQ_IS_484(freq) && !MAX_COUNT(DecodeTag->count, recv_speed)) { // still in SOF at 484
                DecodeTag->count++;
            } else { // SOF failed, roll back
                DecodeTag->state = STATE_FSK_BEFORE_SOF;
            }
            break;

        case STATE_FSK_SOF_424:
            //DbpString("STATE_FSK_SOF_424");
            if (FREQ_IS_484(freq) && SEOF_COUNT(DecodeTag->count, recv_speed)) {
                // SOF part 1 finished
                DecodeTag->state = STATE_FSK_SOF_END_484;
                DecodeTag->count = 1;
            } else if (FREQ_IS_424(freq) && !MAX_COUNT(DecodeTag->count, recv_speed)) // still in SOF at 424
                DecodeTag->count++;
            else { // SOF failed, roll back
#ifdef DEBUG
                if (DEBUG)
                    Dbprintf("SOF_424 failed: freq=%d, count=%d, recv_speed=%d", freq, DecodeTag->count, recv_speed);
#endif
                DecodeTag->state = STATE_FSK_BEFORE_SOF;
            }
            break;

        case STATE_FSK_SOF_END_484:
            if (FREQ_IS_424(freq) && LOGIC_COUNT(DecodeTag->count, recv_speed)) {
                DecodeTag->state = STATE_FSK_SOF_END_424;
                DecodeTag->count = 1;
            } else if (FREQ_IS_484(freq) && !MAX_COUNT(DecodeTag->count, recv_speed)) // still in SOF_END_484
                DecodeTag->count++;
            else { // SOF failed, roll back
#ifdef DEBUG
                if (DEBUG)
                    Dbprintf("SOF_END_484 failed: freq=%d, count=%d, recv_speed=%d", freq, DecodeTag->count, recv_speed);
#endif
                DecodeTag->state = STATE_FSK_BEFORE_SOF;
            }
            break;
        case STATE_FSK_SOF_END_424:
            if (FREQ_IS_484(freq) && LOGIC_COUNT(DecodeTag->count, recv_speed)) {
                // SOF finished at 484
                DecodeTag->count = 1;
                DecodeTag->lastBit = SOF;
                DecodeTag->state = STATE_FSK_RECEIVING_DATA_484;
                LED_C_ON();
            } else if (FREQ_IS_424(freq) && LOGIC_COUNT(DecodeTag->count - 2, recv_speed)) {
                // SOF finished at 424 (wait count+2 to be sure that next freq is 424)
                DecodeTag->count = 2;
                DecodeTag->lastBit = SOF;
                DecodeTag->state = STATE_FSK_RECEIVING_DATA_424;
                LED_C_ON();
            } else if (FREQ_IS_424(freq) && !MAX_COUNT(DecodeTag->count, recv_speed)) // still in SOF_END_424
                DecodeTag->count++;
            else { // SOF failed, roll back
#ifdef DEBUG
                if (DEBUG)
                    Dbprintf("SOF_END_424 failed: freq=%d, count=%d, recv_speed=%d", freq, DecodeTag->count, recv_speed);
#endif
                DecodeTag->state = STATE_FSK_BEFORE_SOF;
            }
            break;


        case STATE_FSK_RECEIVING_DATA_424:
            if (FREQ_IS_484(freq) && LOGIC_COUNT(DecodeTag->count, recv_speed)) {
                if (DecodeTag->lastBit == LOGIC1_PART1) {
                    // logic 1 finished, goto 484
                    DecodeTag->lastBit = LOGIC1_PART2;

                    DecodeTag->shiftReg >>= 1;
                    DecodeTag->shiftReg |= 0x80;
                    DecodeTag->bitCount++;
                    if (DecodeTag->bitCount == 8) {
                        DecodeTag->output[DecodeTag->len++] = DecodeTag->shiftReg;
                        if (DecodeTag->len > DecodeTag->max_len) {
                            // buffer overflow, give up
                            LED_C_OFF();
                            return true;
                        }
                        DecodeTag->bitCount = 0;
                        DecodeTag->shiftReg = 0;
                    }
                } else {
                    // end of LOGIC0_PART1
                    DecodeTag->lastBit = LOGIC0_PART1;
                }
                DecodeTag->count = 1;
                DecodeTag->state = STATE_FSK_RECEIVING_DATA_484;
            } else if (FREQ_IS_424(freq) && LOGIC_COUNT(DecodeTag->count - 2, recv_speed) &&
                       DecodeTag->lastBit == LOGIC1_PART1) {
                // logic 1 finished, stay in 484
                DecodeTag->lastBit = LOGIC1_PART2;

                DecodeTag->shiftReg >>= 1;
                DecodeTag->shiftReg |= 0x80;
                DecodeTag->bitCount++;
                if (DecodeTag->bitCount == 8) {
                    DecodeTag->output[DecodeTag->len++] = DecodeTag->shiftReg;
                    if (DecodeTag->len > DecodeTag->max_len) {
                        // buffer overflow, give up
                        LED_C_OFF();
                        return true;
                    }
                    DecodeTag->bitCount = 0;
                    DecodeTag->shiftReg = 0;
                }
                DecodeTag->count = 2;
            } else if (FREQ_IS_424(freq) && !MAX_COUNT(DecodeTag->count, recv_speed)) // still at 424
                DecodeTag->count++;

            else if (FREQ_IS_484(freq) && DecodeTag->lastBit == LOGIC0_PART2 &&
                     SEOF_COUNT(DecodeTag->count, recv_speed)) {
                // EOF has started
#ifdef DEBUG
                if (DEBUG)
                    Dbprintf("RECEIVING_DATA_424->EOF: freq=%d, count=%d, recv_speed=%d, lastbit=%d, state=%d", freq, DecodeTag->count, recv_speed, DecodeTag->lastBit, DecodeTag->state);
#endif
                DecodeTag->count = 1;
                DecodeTag->state = STATE_FSK_EOF;
                LED_C_OFF();
            } else { // error
#ifdef DEBUG
                if (DEBUG)
                    Dbprintf("RECEIVING_DATA_424 error: freq=%d, count=%d, recv_speed=%d, lastbit=%d, state=%d", freq, DecodeTag->count, recv_speed, DecodeTag->lastBit, DecodeTag->state);
#endif
                DecodeTag->state = STATE_FSK_ERROR;
                LED_C_OFF();
                return true;
            }
            break;

        case STATE_FSK_RECEIVING_DATA_484:
            if (FREQ_IS_424(freq) && LOGIC_COUNT(DecodeTag->count, recv_speed)) {
                if (DecodeTag->lastBit == LOGIC0_PART1) {
                    // logic 0 finished, goto 424
                    DecodeTag->lastBit = LOGIC0_PART2;

                    DecodeTag->shiftReg >>= 1;
                    DecodeTag->bitCount++;
                    if (DecodeTag->bitCount == 8) {
                        DecodeTag->output[DecodeTag->len++] = DecodeTag->shiftReg;
                        if (DecodeTag->len > DecodeTag->max_len) {
                            // buffer overflow, give up
                            LED_C_OFF();
                            return true;
                        }
                        DecodeTag->bitCount = 0;
                        DecodeTag->shiftReg = 0;
                    }
                } else {
                    // end of LOGIC1_PART1
                    DecodeTag->lastBit = LOGIC1_PART1;
                }
                DecodeTag->count = 1;
                DecodeTag->state = STATE_FSK_RECEIVING_DATA_424;
            } else if (FREQ_IS_484(freq) && LOGIC_COUNT(DecodeTag->count - 2, recv_speed) &&
                       DecodeTag->lastBit == LOGIC0_PART1) {
                // logic 0 finished, stay in 424
                DecodeTag->lastBit = LOGIC0_PART2;

                DecodeTag->shiftReg >>= 1;
                DecodeTag->bitCount++;
                if (DecodeTag->bitCount == 8) {
                    DecodeTag->output[DecodeTag->len++] = DecodeTag->shiftReg;
                    if (DecodeTag->len > DecodeTag->max_len) {
                        // buffer overflow, give up
                        LED_C_OFF();
                        return true;
                    }
                    DecodeTag->bitCount = 0;
                    DecodeTag->shiftReg = 0;
                }
                DecodeTag->count = 2;
            } else if (FREQ_IS_484(freq) && !MAX_COUNT(DecodeTag->count, recv_speed)) // still at 484
                DecodeTag->count++;
            else { // error
#ifdef DEBUG
                if (DEBUG)
                    Dbprintf("RECEIVING_DATA_484 error: freq=%d, count=%d, recv_speed=%d, lastbit=%d, state=%d", freq, DecodeTag->count, recv_speed, DecodeTag->lastBit, DecodeTag->state);
#endif
                LED_C_OFF();
                DecodeTag->state = STATE_FSK_ERROR;
                return true;
            }
            break;

        case STATE_FSK_EOF:
            if (FREQ_IS_484(freq) && !MAX_COUNT(DecodeTag->count, recv_speed)) { // still at 484
                DecodeTag->count++;
                if (SEOF_COUNT(DecodeTag->count, recv_speed))
                    return true; // end of the transmission
            } else { // error
#ifdef DEBUG
                if (DEBUG)
                    Dbprintf("EOF error: freq=%d, count=%d, recv_speed=%d", freq, DecodeTag->count, recv_speed);
#endif
                DecodeTag->state = STATE_FSK_ERROR;
                return true;
            }
            break;
        case STATE_FSK_ERROR:
            LED_C_OFF();
#ifdef DEBUG
            if (DEBUG)
                Dbprintf("FSK error: freq=%d, count=%d, recv_speed=%d", freq, DecodeTag->count, recv_speed);
#endif
            return true; // error
            break;
    }
    return false;
}

/*
 *  Receive and decode the tag response, also log to tracebuffer
 */
int GetIso15693AnswerFromTag(uint8_t *response, uint16_t max_len, uint16_t timeout, uint32_t *eof_time, bool fsk, bool recv_speed, uint16_t *resp_len) {

    int samples = 0, ret = PM3_SUCCESS;
    if (resp_len) {
        *resp_len = 0;
    }
    // the Decoder data structure
    DecodeTag_t dtm = { 0 };
    DecodeTag_t *dt = &dtm;

    DecodeTagFSK_t dtfm = { 0 };
    DecodeTagFSK_t *dtf = &dtfm;

    if (fsk)
        DecodeTagFSKInit(dtf, response, max_len);
    else
        DecodeTagInit(dt, response, max_len);

    // wait for last transfer to complete
    while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));

    // And put the FPGA in the appropriate mode
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_2SUBCARRIERS_424_484_KHZ | FPGA_HF_READER_MODE_RECEIVE_AMPLITUDE);

    // Setup and start DMA.
    FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);

    // The DMA buffer, used to stream samples from the FPGA
    dmabuf16_t *dma = get_dma16();

    // Setup and start DMA.
    if (FpgaSetupSscDma((uint8_t *) dma->buf, DMA_BUFFER_SIZE) == false) {
        if (g_dbglevel > DBG_ERROR) Dbprintf("FpgaSetupSscDma failed. Exiting");
        return PM3_EINIT;
    }

    uint32_t dma_start_time = 0;
    uint16_t *upTo = dma->buf;

    for (;;) {

        volatile uint16_t behindBy = ((uint16_t *)AT91C_BASE_PDC_SSC->PDC_RPR - upTo) & (DMA_BUFFER_SIZE - 1);
        if (behindBy == 0)
            continue;

        samples++;
        if (samples == 1) {
            // DMA has transferred the very first data
            dma_start_time = GetCountSspClk() & 0xfffffff0;
        }

        volatile uint16_t tagdata = *upTo++;

        if (upTo >= dma->buf + DMA_BUFFER_SIZE) {                // we have read all of the DMA buffer content.
            upTo = dma->buf;                                     // start reading the circular buffer from the beginning

            // DMA Counter Register had reached 0, already rotated.
            if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {

                // primary buffer was stopped
                if (AT91C_BASE_PDC_SSC->PDC_RCR == false) {
                    AT91C_BASE_PDC_SSC->PDC_RPR = (uint32_t) dma->buf;
                    AT91C_BASE_PDC_SSC->PDC_RCR = DMA_BUFFER_SIZE;
                }
                // secondary buffer sets as primary, secondary buffer was stopped
                if (AT91C_BASE_PDC_SSC->PDC_RNCR == false) {
                    AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dma->buf;
                    AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
                }

                WDT_HIT();
                if (BUTTON_PRESS()) {
                    break;
                }
            }
        }

        if (fsk) {

            if (Handle15693FSKSamplesFromTag(tagdata >> 14, dtf, recv_speed)) {

                *eof_time = dma_start_time + (samples * 16) - DELAY_TAG_TO_ARM; // end of EOF

                if (dtf->lastBit == SOF) {
                    *eof_time -= (8 * 16); // needed 8 additional samples to confirm single SOF (iCLASS)
                }

                if (dtf->len > dtf->max_len) {
                    ret = PM3_EOVFLOW;
                    Dbprintf("overflow (%d > %d)", dtf->len, dtf->max_len);
                }
                break;
            }

            // timeout
            if (samples > timeout && dtf->state < STATE_FSK_RECEIVING_DATA_484) {
                ret = PM3_ETIMEOUT;
                break;
            }

        } else {

            if (Handle15693SamplesFromTag(tagdata & 0x3FFF, dt, recv_speed)) {

                *eof_time = dma_start_time + (samples * 16) - DELAY_TAG_TO_ARM; // end of EOF

                if (dt->lastBit == SOF_PART2) {
                    *eof_time -= (8 * 16); // needed 8 additional samples to confirm single SOF (iCLASS)
                }

                if (dt->len > dt->max_len) {
                    ret = PM3_EOVFLOW;
                    Dbprintf("overflow (%d > %d)", dt->len, dt->max_len);
                }
                break;
            }

            // timeout
            if (samples > timeout && dt->state < STATE_TAG_RECEIVING_DATA) {
                ret = PM3_ETIMEOUT;
                break;
            }
        }
    }

    FpgaDisableSscDma();
    FpgaDisableTracing();

    uint32_t sof_time = *eof_time - (32 * 16);  // time for SOF transfer

    if (fsk) {
        sof_time -= (dtf->len * 8 * 8 * 16) // time for byte transfers
                    + (dtf->lastBit != SOF ? (32 * 16) : 0); // time for EOF transfer
    } else {
        sof_time -= (dt->len * 8 * 8 * 16) // time for byte transfers
                    + (dt->lastBit != SOF_PART2 ? (32 * 16) : 0); // time for EOF transfer
    }

    if (ret != PM3_SUCCESS) {
        *resp_len = 0;
        return ret;
    }

    if (fsk) {
        LogTrace_ISO15693(dtf->output, dtf->len, (sof_time * 4), (*eof_time * 4), NULL, false);
        *resp_len = dtf->len;
    } else {
        LogTrace_ISO15693(dt->output, dt->len, (sof_time * 4), (*eof_time * 4), NULL, false);
        *resp_len = dt->len;
    }
    return PM3_SUCCESS;
}


//=============================================================================
// An ISO15693 decoder for reader commands.
//
// This function is called 4 times per bit (every 2 subcarrier cycles).
// Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 2,36us
// LED handling:
//    LED B -> ON once we have received the SOF and are expecting the rest.
//    LED B -> OFF once we have received EOF or are in error state or unsynced
//
// Returns: true  if we received a EOF
//          false if we are still waiting for some more
//=============================================================================

typedef struct {
    enum {
        STATE_READER_UNSYNCD,
        STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF,
        STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF,
        STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF,
        STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF,
        STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4,
        STATE_READER_RECEIVE_DATA_1_OUT_OF_4,
        STATE_READER_RECEIVE_DATA_1_OUT_OF_256,
        STATE_READER_RECEIVE_JAMMING
    }           state;
    enum {
        CODING_1_OUT_OF_4,
        CODING_1_OUT_OF_256
    }           Coding;
    uint8_t     shiftReg;
    uint8_t     bitCount;
    int         byteCount;
    int         byteCountMax;
    int         posCount;
    int         sum1, sum2;
    uint8_t     *output;
    uint8_t     jam_search_len;
    uint8_t     *jam_search_string;
} DecodeReader_t;

static void DecodeReaderInit(DecodeReader_t *reader, uint8_t *data, uint16_t max_len, uint8_t jam_search_len, uint8_t *jam_search_string) {
    reader->output = data;
    reader->byteCountMax = max_len;
    reader->state = STATE_READER_UNSYNCD;
    reader->byteCount = 0;
    reader->bitCount = 0;
    reader->posCount = 1;
    reader->shiftReg = 0;
    reader->jam_search_len = jam_search_len;
    reader->jam_search_string = jam_search_string;
}

static void DecodeReaderReset(DecodeReader_t *reader) {
    reader->state = STATE_READER_UNSYNCD;
}

//static inline __attribute__((always_inline))
static int RAMFUNC Handle15693SampleFromReader(bool bit, DecodeReader_t *reader) {
    switch (reader->state) {
        case STATE_READER_UNSYNCD:
            // wait for unmodulated carrier
            if (bit) {
                reader->state = STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF;
            }
            break;

        case STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF:
            if (!bit) {
                // we went low, so this could be the beginning of a SOF
                reader->posCount = 1;
                reader->state = STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF;
            }
            break;

        case STATE_READER_AWAIT_1ST_RISING_EDGE_OF_SOF:
            if (bit) { // detected rising edge
                if (reader->posCount < 2) { // rising edge too early (nominally expected at 4)
                    reader->state = STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF;
                } else { // SOF
                    reader->state = STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF;
                    reader->posCount = 1;
                }
            } else {
                reader->posCount++;
                if (reader->posCount > 6) { // stayed low for too long
                    DecodeReaderReset(reader);
                }
            }
            break;

        case STATE_READER_AWAIT_2ND_FALLING_EDGE_OF_SOF:
            if (!bit) { // detected a falling edge
                if (reader->posCount < 14) {         // falling edge too early (nominally expected at 16 earliest)
                    DecodeReaderReset(reader);
                } else if (reader->posCount <= 18) {  // SOF for 1 out of 4 coding
                    reader->Coding = CODING_1_OUT_OF_4;
                    reader->state = STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF;
                    reader->posCount = 1;
                } else if (reader->posCount < 22) {  // falling edge too early (nominally expected at 24 latest)
                    DecodeReaderReset(reader);
                } else {                             // SOF for 1 out of 256 coding
                    reader->Coding = CODING_1_OUT_OF_256;
                    reader->state = STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF;
                    reader->posCount = 1;
                }
            } else {
                reader->posCount++;
                if (reader->posCount > 26) { // stayed high for too long
                    reader->state = STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF;
                } else {
                    // do nothing, keep waiting
                }
            }
            break;

        case STATE_READER_AWAIT_2ND_RISING_EDGE_OF_SOF:
            if (bit) { // detected rising edge
                if (reader->posCount < 2) { // rising edge too early (nominally expected at 8)
                    reader->state = STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF;
                } else {
                    reader->posCount = 1;
                    if (reader->Coding == CODING_1_OUT_OF_256) {
                        reader->bitCount = 1;
                        reader->byteCount = 0;
                        reader->sum1 = 1;
                        LED_B_ON();
                        reader->state = STATE_READER_RECEIVE_DATA_1_OUT_OF_256;
                    } else { // CODING_1_OUT_OF_4
                        reader->state = STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4;
                    }
                }
            } else {
                reader->posCount++;
                if (reader->posCount > 6) { // signal stayed low for too long
                    DecodeReaderReset(reader);
                } else {
                    // do nothing, keep waiting
                }
            }
            break;

        case STATE_READER_AWAIT_END_OF_SOF_1_OUT_OF_4:
            if (bit) {
                reader->posCount++;

                if (reader->posCount == 8) {
                    reader->posCount = 0;
                    reader->bitCount = 0;
                    reader->byteCount = 0;
                    reader->sum1 = 0;
                    reader->state = STATE_READER_RECEIVE_DATA_1_OUT_OF_4;
                    LED_B_ON();
                }
            } else { // unexpected falling edge
                DecodeReaderReset(reader);
            }
            break;

        case STATE_READER_RECEIVE_DATA_1_OUT_OF_4:
            if (!bit) {
                reader->sum1++;
                if (reader->sum1 == 1) { // first low bit
                    if (reader->posCount <= 6) { // bits : 00
                        reader->shiftReg >>= 2;
                        //reader->shiftReg |= (0 << 6);
                        reader->bitCount += 2;
                        reader->posCount = -28;
                    } else if (reader->posCount <= 9) { // EOF
                        LED_B_OFF(); // Finished receiving
                        DecodeReaderReset(reader);
                        if (reader->byteCount > 0) {
                            return true;
                        }
                    } else if (reader->posCount <= 14) { // bits : 01
                        reader->shiftReg >>= 2;
                        reader->shiftReg |= (1 << 6);
                        reader->bitCount += 2;
                        reader->posCount = -20;
                    } else if (reader->posCount < 18) { // unexpected falling edge
                        DecodeReaderReset(reader);
                        if (reader->byteCount >= 0) {
                            reader->output[reader->byteCount++] = reader->posCount;
                            reader->output[reader->byteCount++] = reader->bitCount;
                            reader->output[reader->byteCount++] = 0x42;
                            return true;
                        }
                    } else if (reader->posCount <= 22) { // bits : 10
                        reader->shiftReg >>= 2;
                        reader->shiftReg |= (2 << 6);
                        reader->bitCount += 2;
                        reader->posCount = -12;
                    } else if (reader->posCount < 26) { // unexpected falling edge
                        DecodeReaderReset(reader);
                        if (reader->byteCount >= 0) {
                            reader->output[reader->byteCount++] = reader->posCount;
                            reader->output[reader->byteCount++] = reader->bitCount;
                            reader->output[reader->byteCount++] = 0x43;
                            return true;
                        }
                    } else { // bits : 11
                        reader->shiftReg >>= 2;
                        reader->shiftReg |= (3 << 6);
                        reader->bitCount += 2;
                        reader->posCount = -4;
                    }

                    if (reader->bitCount == 8) {
                        reader->output[reader->byteCount++] = reader->shiftReg;
                        if (reader->byteCount > reader->byteCountMax) {
                            // buffer overflow, give up
                            LED_B_OFF();
                            DecodeReaderReset(reader);
                        }

                        reader->bitCount = 0;
                        reader->shiftReg = 0;
                        if (reader->byteCount == reader->jam_search_len) {
                            if (!memcmp(reader->output, reader->jam_search_string, reader->jam_search_len)) {
                                LED_D_ON();
                                FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SEND_JAM);
                                reader->state = STATE_READER_RECEIVE_JAMMING;
                            }
                        }
                    }
                } else if (reader->sum1 > 6) { // too long low bit
                    DecodeReaderReset(reader);
                    if (reader->byteCount >= 0) {
                        reader->output[reader->byteCount++] = reader->posCount;
                        reader->output[reader->byteCount++] = reader->bitCount;
                        reader->output[reader->byteCount++] = 0x44;
                        return true;
                    }
                }
            } else {
                reader->posCount++;
                if (reader->posCount > 30) {
                    reader->state = STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF;
                    if (reader->byteCount >= 0) {
                        reader->output[reader->byteCount++] = reader->posCount;
                        reader->output[reader->byteCount++] = reader->bitCount;
                        reader->output[reader->byteCount++] = 0x45;
                        return true;
                    }
                }
                if (reader->sum1 == 1) {
                    reader->state = STATE_READER_AWAIT_1ST_FALLING_EDGE_OF_SOF;
                    if (reader->byteCount >= 0) {
                        reader->output[reader->byteCount++] = reader->posCount;
                        reader->output[reader->byteCount++] = reader->bitCount;
                        reader->output[reader->byteCount++] = 0x46;
                        return true;
                    }
                } else if (reader->sum1 > 1) {
                    reader->posCount += reader->sum1;
                    reader->sum1 = 0;
                }
            }
            break;

        case STATE_READER_RECEIVE_DATA_1_OUT_OF_256:

            reader->posCount++;

            if (reader->posCount == 1) {
                reader->sum1 = bit ? 1 : 0;
            } else if (reader->posCount <= 4) {
                if (bit) reader->sum1++;
            } else if (reader->posCount == 5) {
                reader->sum2 = bit ? 1 : 0;
            } else if (bit) {
                reader->sum2++;
            }

            if (reader->posCount == 8) {
                reader->posCount = 0;
                if (reader->sum1 <= 1 && reader->sum2 >= 3) { // EOF
                    LED_B_OFF(); // Finished receiving
                    DecodeReaderReset(reader);
                    if (reader->byteCount != 0) {
                        return true;
                    }

                } else if (reader->sum1 >= 3 && reader->sum2 <= 1) { // detected the bit position
                    reader->shiftReg = reader->bitCount;
                }

                if (reader->bitCount == 255) { // we have a full byte
                    reader->output[reader->byteCount++] = reader->shiftReg;
                    if (reader->byteCount > reader->byteCountMax) {
                        // buffer overflow, give up
                        LED_B_OFF();
                        DecodeReaderReset(reader);
                    }

                    if (reader->byteCount == reader->jam_search_len) {
                        if (!memcmp(reader->output, reader->jam_search_string, reader->jam_search_len)) {
                            LED_D_ON();
                            FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SEND_JAM);
                            reader->state = STATE_READER_RECEIVE_JAMMING;
                        }
                    }
                }
                reader->bitCount++;
            }
            break;

        case STATE_READER_RECEIVE_JAMMING:

            reader->posCount++;

            if (reader->Coding == CODING_1_OUT_OF_4) {
                if (reader->posCount == 7 * 16) { // 7 bits jammed
                    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SNIFF_AMPLITUDE); // stop jamming
                    // FpgaDisableTracing();
                    LED_D_OFF();
                } else if (reader->posCount == 8 * 16) {
                    reader->posCount = 0;
                    reader->output[reader->byteCount++] = 0x00;
                    reader->state = STATE_READER_RECEIVE_DATA_1_OUT_OF_4;
                }
            } else {
                if (reader->posCount == 7 * 256) { // 7 bits jammend
                    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SNIFF_AMPLITUDE); // stop jamming
                    LED_D_OFF();
                } else if (reader->posCount == 8 * 256) {
                    reader->posCount = 0;
                    reader->output[reader->byteCount++] = 0x00;
                    reader->state = STATE_READER_RECEIVE_DATA_1_OUT_OF_256;
                }
            }
            break;

        default:
            LED_B_OFF();
            DecodeReaderReset(reader);
            break;
    }

    return false;
}

//-----------------------------------------------------------------------------
// Receive a command (from the reader to us, where we are the simulated tag),
// and store it in the given buffer, up to the given maximum length. Keeps
// spinning, waiting for a well-framed command, until either we get one
// (returns len) or someone presses the pushbutton on the board (returns -1).
//
// Assume that we're called with the SSC (to the FPGA) and ADC path set
// correctly.
//-----------------------------------------------------------------------------

int GetIso15693CommandFromReader(uint8_t *received, size_t max_len, uint32_t *eof_time) {
    int samples = 0;
    bool gotFrame = false;

    // the decoder data structure
    DecodeReader_t *dr = (DecodeReader_t *)BigBuf_malloc(sizeof(DecodeReader_t));
    DecodeReaderInit(dr, received, max_len, 0, NULL);

    // wait for last transfer to complete
    while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY));

    LED_D_OFF();
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);

    // clear receive register and wait for next transfer
    uint32_t temp = AT91C_BASE_SSC->SSC_RHR;
    (void) temp;
    while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)) ;

    // Setup and start DMA.
    dmabuf8_t *dma = get_dma8();
    if (FpgaSetupSscDma(dma->buf, DMA_BUFFER_SIZE) == false) {
        if (g_dbglevel > DBG_ERROR) Dbprintf("FpgaSetupSscDma failed. Exiting");
        return -4;
    }
    uint8_t *upTo = dma->buf;

    uint32_t dma_start_time = GetCountSspClk() & 0xfffffff8;

    for (;;) {
        volatile uint16_t behindBy = ((uint8_t *)AT91C_BASE_PDC_SSC->PDC_RPR - upTo) & (DMA_BUFFER_SIZE - 1);
        if (behindBy == 0) continue;

        if (samples == 0) {
            // DMA has transferred the very first data
            dma_start_time = GetCountSspClk() & 0xfffffff0;
        }

        volatile uint8_t b = *upTo++;
        if (upTo >= dma->buf + DMA_BUFFER_SIZE) {               // we have read all of the DMA buffer content.
            upTo = dma->buf;                                    // start reading the circular buffer from the beginning
            if (behindBy > (9 * DMA_BUFFER_SIZE / 10)) {
                Dbprintf("About to blow circular buffer - aborted! behindBy %d", behindBy);
                break;
            }
        }
        if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {       // DMA Counter Register had reached 0, already rotated.
            AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dma->buf; // refresh the DMA Next Buffer and
            AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;     // DMA Next Counter registers
        }

        for (int i = 7; i >= 0; i--) {
            if (Handle15693SampleFromReader((b >> i) & 0x01, dr)) {
                *eof_time = dma_start_time + samples - DELAY_READER_TO_ARM; // end of EOF
                gotFrame = true;
                break;
            }
            samples++;
        }

        if (gotFrame) {
            break;
        }

        if (BUTTON_PRESS()) {
            dr->byteCount = -1;
            break;
        }

        WDT_HIT();
    }

    FpgaDisableSscDma();

    if (dr->byteCount >= 0) {
        uint32_t sof_time = *eof_time
                            - dr->byteCount * (dr->Coding == CODING_1_OUT_OF_4 ? 128 : 2048) // time for byte transfers
                            - 32  // time for SOF transfer
                            - 16; // time for EOF transfer
        LogTrace_ISO15693(dr->output, dr->byteCount, (sof_time * 32), (*eof_time * 32), NULL, true);
    }

    return dr->byteCount;
}

//-----------------------------------------------------------------------------
// Start to read an ISO 15693 tag. We send an identify request, then wait
// for the response. The response is not demodulated, just left in the buffer
// so that it can be downloaded to a PC and processed there.
//-----------------------------------------------------------------------------
void AcquireRawAdcSamplesIso15693(void) {

    LEDsoff();
    DbpString("Starting to acquire data...");
    FpgaDownloadAndGo(FPGA_BITSTREAM_HF_15);

    BigBuf_free();
    clear_trace();

    // Start from off (no field generated)
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
    SpinDelay(10);


    uint8_t cmd[5];
    BuildIdentifyRequest(cmd);
    CodeIso15693AsReader(cmd, sizeof(cmd));

    LED_A_ON();

    uint8_t *dest = BigBuf_malloc(4000);

    // switch field on
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER);
    LED_D_ON();

    // initialize SSC and select proper AD input
    FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
    SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

    StartCountSspClk();

    // Give the tags time to energize
    SpinDelay(250);

    // Now send the command
    tosend_t *ts = get_tosend();

    uint32_t start_time = 0;
    TransmitTo15693Tag(ts->buf, ts->max, &start_time, false);

    // wait for last transfer to complete
    while (!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXEMPTY)) ;

    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_SUBCARRIER_424_KHZ | FPGA_HF_READER_MODE_RECEIVE_AMPLITUDE);

    for (int c = 0; c < 4000;) {
        if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
            uint16_t r = AT91C_BASE_SSC->SSC_RHR;
            dest[c++] = r >> 5;
        }
    }


    FpgaDisableSscDma();
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
    LEDsoff();
}

void SniffIso15693(uint8_t jam_search_len, uint8_t *jam_search_string, bool iclass) {

    LEDsoff();
    LED_A_ON();

    FpgaDownloadAndGo(FPGA_BITSTREAM_HF_15);

    if (g_dbglevel >= DBG_INFO) {
        DbpString("Press " _GREEN_("pm3 button") " to abort sniffing");
    }
    BigBuf_free();
    clear_trace();
    set_tracing(true);

    DecodeTag_t dtag = {0};
    uint8_t response[ISO15693_MAX_RESPONSE_LENGTH] = {0};
    DecodeTagInit(&dtag, response, sizeof(response));

    DecodeTagFSK_t dtagfsk = {0};
    uint8_t response2[ISO15693_MAX_RESPONSE_LENGTH] = {0};
    DecodeTagFSKInit(&dtagfsk, response2, sizeof(response2));

    DecodeReader_t dreader = {0};
    uint8_t cmd[ISO15693_MAX_COMMAND_LENGTH] = {0};
    DecodeReaderInit(&dreader, cmd, sizeof(cmd), jam_search_len, jam_search_string);

    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER | FPGA_HF_READER_MODE_SNIFF_AMPLITUDE | FPGA_HF_READER_2SUBCARRIERS_424_484_KHZ);

    LED_D_OFF();

    SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
    FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);

    StartCountSspClk();

    // The DMA buffer, used to stream samples from the FPGA
    dmabuf16_t *dma = get_dma16();

    // Setup and start DMA.
    if (FpgaSetupSscDma((uint8_t *) dma->buf, DMA_BUFFER_SIZE) == false) {
        if (g_dbglevel > DBG_ERROR) DbpString("FpgaSetupSscDma failed. Exiting");
        switch_off();
        return;
    }

    bool tag_is_active = false;
    bool reader_is_active = false;
    bool expect_tag_answer = false;
    bool expect_fsk_answer = false;
    bool expect_fast_answer = true; // default to true is required for iClass
    int dma_start_time = 0;

    // Count of samples received so far, so that we can include timing
    int samples = 0;

    uint16_t *upTo = dma->buf;

    for (;;) {

        volatile int behind_by = ((uint16_t *)AT91C_BASE_PDC_SSC->PDC_RPR - upTo) & (DMA_BUFFER_SIZE - 1);
        if (behind_by < 1) continue;

        samples++;
        if (samples == 1) {
            // DMA has transferred the very first data
            dma_start_time = GetCountSspClk() & 0xfffffff0;
        }

        volatile uint16_t sniffdata = 0;
        volatile uint16_t sniffdata_prev = sniffdata;
        sniffdata = *upTo++;

        // we have read all of the DMA buffer content
        if (upTo >= dma->buf + DMA_BUFFER_SIZE) {

            // start reading the circular buffer from the beginning
            upTo = dma->buf;

            // DMA Counter Register had reached 0, already rotated.
            if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_ENDRX)) {

                // primary buffer was stopped
                if (AT91C_BASE_PDC_SSC->PDC_RCR == false) {
                    AT91C_BASE_PDC_SSC->PDC_RPR = (uint32_t) dma->buf;
                    AT91C_BASE_PDC_SSC->PDC_RCR = DMA_BUFFER_SIZE;
                }
                // secondary buffer sets as primary, secondary buffer was stopped
                if (AT91C_BASE_PDC_SSC->PDC_RNCR == false) {
                    AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dma->buf;
                    AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
                }

                WDT_HIT();
                if (BUTTON_PRESS()) {
                    break;
                }
            }
        }

        // no need to try decoding reader data if the tag is sending
        if (tag_is_active == false) {

            int extra_8s = 1;
            if (Handle15693SampleFromReader((sniffdata & 0x02) >> 1, &dreader) ||
                    (++extra_8s && Handle15693SampleFromReader(sniffdata & 0x01, &dreader))) {

                if (dreader.byteCount > 0) {
                    // sof/eof_times are in ssp_clk, which is 13.56MHz / 4
                    // not sure where the extra +8's on the EOF time comes from though, if someone knows update this comment
                    uint32_t eof_time = dma_start_time + (samples * 16) + (extra_8s * 8) - DELAY_READER_TO_ARM_SNIFF; // end of EOF
                    uint32_t sof_time = eof_time
                                        - dreader.byteCount * (dreader.Coding == CODING_1_OUT_OF_4 ? 1024 : 16384) // time for byte transfers
                                        - 256  // time for SOF transfer (1024/fc / 4)
                                        - 128; // time for EOF transfer (512/fc / 4)
                    // sof/eof_times * 4 here to bring from ssp_clk freq to RF carrier freq
                    LogTrace_ISO15693(dreader.output, dreader.byteCount, (sof_time * 4), (eof_time * 4), NULL, true);

                    if (iclass == false) { // Those flags don't exist in iClass
                        expect_fsk_answer = dreader.output[0] & ISO15_REQ_SUBCARRIER_TWO;
                        expect_fast_answer = dreader.output[0] & ISO15_REQ_DATARATE_HIGH;
                    }
                }

                // And ready to receive another command.
                //DecodeReaderReset(&dreader); // already reseted
                DecodeTagReset(&dtag);
                DecodeTagFSKReset(&dtagfsk);
                reader_is_active = false;
                expect_tag_answer = true;
            } else {
                reader_is_active = (dreader.state >= STATE_READER_RECEIVE_DATA_1_OUT_OF_4);
            }
        }

        // no need to try decoding tag data if the reader is currently sending or no answer expected yet
        if ((reader_is_active == false) && expect_tag_answer) {

            if (expect_fsk_answer == false) {
                // single subcarrier tag response
                if (Handle15693SamplesFromTag((sniffdata >> 4) << 2, &dtag, expect_fast_answer)) {

                    // sof/eof_times are in ssp_clk, which is 13.56MHz / 4
                    uint32_t eof_time = dma_start_time + (samples * 16) - DELAY_TAG_TO_ARM_SNIFF; // end of EOF

                    if (dtag.lastBit == SOF_PART2) {
                        eof_time -= (8 * 16); // needed 8 additional samples to confirm single SOF (iCLASS)
                    }

                    uint32_t sof_time = eof_time
                                        - dtag.len * 1024 // time for byte transfers (4096/fc / 4)
                                        - 512             // time for SOF transfer (2048/fc / 4)
                                        - (dtag.lastBit != SOF_PART2 ? 512 : 0); // time for EOF transfer (2048/fc / 4)

                    // sof/eof_times * 4 here to bring from ssp_clk freq to RF carrier freq
                    LogTrace_ISO15693(dtag.output, dtag.len, (sof_time * 4), (eof_time * 4), NULL, false);

                    // And ready to receive another response.
                    DecodeTagReset(&dtag);
                    DecodeTagFSKReset(&dtagfsk);
                    DecodeReaderReset(&dreader);
                    expect_tag_answer = false;
                    tag_is_active = false;
                } else {
                    tag_is_active = (dtag.state >= STATE_TAG_RECEIVING_DATA);
                }

            } else {
                // dual subcarrier tag response
                if (FREQ_IS_0((sniffdata >> 2) & 0x3))  { // tolerate 1 00
                    sniffdata = sniffdata_prev;
                }

                if (Handle15693FSKSamplesFromTag((sniffdata >> 2) & 0x3, &dtagfsk, expect_fast_answer)) {
                    if (dtagfsk.len > 0) {
                        // sof/eof_times are in ssp_clk, which is 13.56MHz / 4
                        uint32_t eof_time = dma_start_time + (samples * 16) - DELAY_TAG_TO_ARM_SNIFF; // end of EOF

                        if (dtagfsk.lastBit == SOF) {
                            eof_time -= (8 * 16); // needed 8 additional samples to confirm single SOF (iCLASS)
                        }

                        uint32_t sof_time = eof_time
                                            - dtagfsk.len * 1016 // time for byte transfers (4064/fc / 4) - FSK is slightly different
                                            - 512                // time for SOF transfer (2048/fc / 4)
                                            - (dtagfsk.lastBit != SOF ? 512 : 0); // time for EOF transfer (2048/fc / 4)

                        // sof/eof_times * 4 here to bring from ssp_clk freq to RF carrier freq
                        LogTrace_ISO15693(dtagfsk.output, dtagfsk.len, (sof_time * 4), (eof_time * 4), NULL, false);
                    }

                    DecodeTagFSKReset(&dtagfsk);
                    DecodeReaderReset(&dreader);
                    expect_tag_answer = false;
                    tag_is_active = false;
                    // FSK answer no more expected: switch back to ASK
                    expect_fsk_answer = false;
                } else {
                    tag_is_active = (dtagfsk.state >= STATE_FSK_RECEIVING_DATA_484);
                }
            }
        }
    }

    FpgaDisableTracing();
    switch_off();

    DbpString("");
    if (g_dbglevel > DBG_ERROR) {
        DbpString(_CYAN_("Sniff statistics"));
        DbpString("=================================");
        Dbprintf("DecodeTag State........ %d", dtag.state);
        Dbprintf("DecodeTag byteCnt...... %d", dtag.len);
        Dbprintf("DecodeTag posCount..... %d", dtag.posCount);
        Dbprintf("DecodeTagFSK State..... %d", dtagfsk.state);
        Dbprintf("DecodeTagFSK byteCnt... %d", dtagfsk.len);
        Dbprintf("DecodeTagFSK count..... %d", dtagfsk.count);
        Dbprintf("DecodeReader State..... %d", dreader.state);
        Dbprintf("DecodeReader byteCnt... %d", dreader.byteCount);
        Dbprintf("DecodeReader posCount.. %d", dreader.posCount);
    }
    Dbprintf("Trace length........... " _YELLOW_("%d"), BigBuf_get_traceLen());
}

// Initialize Proxmark3 as ISO15693 reader
void Iso15693InitReader(void) {

    LEDsoff();
    FpgaDownloadAndGo(FPGA_BITSTREAM_HF_15);

    // Start from off (no field generated)
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
    SpinDelay(10);

    // switch field on
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER);
    LED_D_ON();

    // initialize SSC and select proper AD input
    FpgaSetupSsc(FPGA_MAJOR_MODE_HF_READER);
    SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

    set_tracing(true);

    // give tags some time to energize
    SpinDelay(250);

    StartCountSspClk();
}

///////////////////////////////////////////////////////////////////////
// ISO 15693 Part 3 - Air Interface
// This section basically contains transmission and receiving of bits
///////////////////////////////////////////////////////////////////////

// Encode an identify request, which is the first
// thing that you must send to a tag to get a response.
// It expects "cmdout" to be at least CMD_ID_RESP large
// When READER:
static void BuildIdentifyRequest(uint8_t *cmd) {
    // flags
    cmd[0] = ISO15_REQ_SUBCARRIER_SINGLE | ISO15_REQ_DATARATE_HIGH | ISO15_REQ_INVENTORY | ISO15_REQINV_SLOT1;
    // inventory command code
    cmd[1] = ISO15693_INVENTORY;
    // no mask
    cmd[2] = 0x00;
    // CRC
    AddCrc15(cmd, 3);
}

// Universal Method for sending to and recv bytes from a tag
//  init ... should we initialize the reader?
//  speed ... 0 low speed, 1 hi speed
//  **recv will return you a pointer to the received data
//  If you do not need the answer use NULL for *recv[]
//  return: length of received data
// logging enabled
int SendDataTag(uint8_t *send, int sendlen, bool init, bool speed_fast, uint8_t *recv,
                uint16_t max_recv_len, uint32_t start_time, uint16_t timeout, uint32_t *eof_time, uint16_t *resp_len) {

    if (init) {
        Iso15693InitReader();
        start_time = GetCountSspClk();
    }

    if (speed_fast) {
        // high speed (1 out of 4)
        CodeIso15693AsReader(send, sendlen);
    } else {
        // low speed (1 out of 256)
        CodeIso15693AsReader256(send, sendlen);
    }

    tosend_t *ts = get_tosend();
    TransmitTo15693Tag(ts->buf, ts->max, &start_time, false);

    if (tearoff_hook() == PM3_ETEAROFF) { // tearoff occurred
        *resp_len = 0;
        return PM3_ETEAROFF;
    } else {

        int res = PM3_SUCCESS;
        *eof_time = start_time + 32 * ((8 * ts->max) - 4); // subtract the 4 padding bits after EOF
        LogTrace_ISO15693(send, sendlen, (start_time * 4), (*eof_time * 4), NULL, true);
        if (recv != NULL) {
            bool fsk = ((send[0] & ISO15_REQ_SUBCARRIER_TWO) == ISO15_REQ_SUBCARRIER_TWO);
            bool recv_speed = ((send[0] & ISO15_REQ_DATARATE_HIGH) == ISO15_REQ_DATARATE_HIGH);
            res = GetIso15693AnswerFromTag(recv, max_recv_len, timeout, eof_time, fsk, recv_speed, resp_len);
        }
        return res;
    }
}

int SendDataTagEOF(uint8_t *recv, uint16_t max_recv_len, uint32_t start_time, uint16_t timeout, uint32_t *eof_time, bool fsk, bool recv_speed, uint16_t *resp_len) {

    CodeIso15693AsReaderEOF();
    tosend_t *ts = get_tosend();
    TransmitTo15693Tag(ts->buf, ts->max, &start_time, false);
    uint32_t end_time = start_time + 32 * (8 * ts->max - 4); // subtract the 4 padding bits after EOF
    LogTrace_ISO15693(NULL, 0, (start_time * 4), (end_time * 4), NULL, true);

    int res = PM3_SUCCESS;
    if (recv) {
        res = GetIso15693AnswerFromTag(recv, max_recv_len, timeout, eof_time, fsk, recv_speed, resp_len);
    }
    return res;
}

// --------------------------------------------------------------------
// Debug Functions
// --------------------------------------------------------------------

// Decodes a message from a tag and displays its metadata and content
#define DBD15STATLEN 48
static void DbdecodeIso15693Answer(int len, uint8_t *d) {

    if (len > 3) {

        char status[DBD15STATLEN + 1] = {0};

        if (d[0] & ISO15_RES_EXT)
            strncat(status, "ProtExt ", DBD15STATLEN - strlen(status));

        if (d[0] & ISO15_RES_ERROR) {
            // error
            strncat(status, "Error ", DBD15STATLEN - strlen(status));
            switch (d[1]) {
                case 0x01:
                    strncat(status, "01: not supported", DBD15STATLEN - strlen(status));
                    break;
                case 0x02:
                    strncat(status, "02: not recognized", DBD15STATLEN - strlen(status));
                    break;
                case 0x03:
                    strncat(status, "03: opt not supported", DBD15STATLEN - strlen(status));
                    break;
                case 0x0f:
                    strncat(status, "0F: no info", DBD15STATLEN - strlen(status));
                    break;
                case 0x10:
                    strncat(status, "10: don't exist", DBD15STATLEN - strlen(status));
                    break;
                case 0x11:
                    strncat(status, "11: lock again", DBD15STATLEN - strlen(status));
                    break;
                case 0x12:
                    strncat(status, "12: locked", DBD15STATLEN - strlen(status));
                    break;
                case 0x13:
                    strncat(status, "13: program error", DBD15STATLEN - strlen(status));
                    break;
                case 0x14:
                    strncat(status, "14: lock error", DBD15STATLEN - strlen(status));
                    break;
                default:
                    strncat(status, "unknown error", DBD15STATLEN - strlen(status));
            }
            strncat(status, " ", DBD15STATLEN - strlen(status));
        } else {
            strncat(status, "No error ", DBD15STATLEN - strlen(status));
        }

        if (CheckCrc15(d, len))
            strncat(status, "[+] crc ( " _GREEN_("ok") " )", DBD15STATLEN - strlen(status));
        else
            strncat(status, "[!] crc ( " _RED_("fail") " )", DBD15STATLEN - strlen(status));

        if (g_dbglevel >= DBG_ERROR) Dbprintf("%s", status);
    }
}

///////////////////////////////////////////////////////////////////////
// Functions called via USB/Client
///////////////////////////////////////////////////////////////////////

//-----------------------------------------------------------------------------
// Act as ISO15693 reader, perform anti-collision and then attempt to read a sector
// all demodulation performed in arm rather than host. - greg
//-----------------------------------------------------------------------------
void ReaderIso15693(iso15_card_select_t *p_card) {

    LED_A_ON();
    set_tracing(true);

    uint8_t *answer = BigBuf_malloc(ISO15693_MAX_RESPONSE_LENGTH);
    memset(answer, 0x00, ISO15693_MAX_RESPONSE_LENGTH);

    // FIRST WE RUN AN INVENTORY TO GET THE TAG UID
    // THIS MEANS WE CAN PRE-BUILD REQUESTS TO SAVE CPU TIME

    // Send the IDENTIFY command
    uint8_t cmd[5] = {0};
    BuildIdentifyRequest(cmd);
    uint32_t start_time = 0;
    uint32_t eof_time;
    uint16_t recvlen = 0;
    int res = SendDataTag(cmd, sizeof(cmd), true, true, answer, ISO15693_MAX_RESPONSE_LENGTH, start_time, ISO15693_READER_TIMEOUT, &eof_time, &recvlen);

    if (res == PM3_ETEAROFF) { // tearoff occurred
        reply_ng(CMD_HF_ISO15693_READER, res, NULL, 0);
    } else {

        //start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;

        // we should do a better check than this
        if (recvlen >= 12) {
            uint8_t uid[8];
            uid[0] = answer[9]; // always E0
            uid[1] = answer[8]; // IC Manufacturer code
            uid[2] = answer[7];
            uid[3] = answer[6];
            uid[4] = answer[5];
            uid[5] = answer[4];
            uid[6] = answer[3];
            uid[7] = answer[2];

            if (p_card != NULL) {
                memcpy(p_card->uid, uid, 8);
                p_card->uidlen = 8;
            }

            if (g_dbglevel >= DBG_EXTENDED) {
                Dbprintf("[+] UID = %02X%02X%02X%02X%02X%02X%02X%02X",
                         uid[0], uid[1], uid[2], uid[3],
                         uid[4], uid[5], uid[5], uid[6]
                        );
            }
            // send UID back to client.
            // arg0 = 1 = OK
            // arg1 = len of response (12 bytes)
            // arg2 = rtf
            // asbytes = uid.
            reply_ng(CMD_HF_ISO15693_READER, PM3_SUCCESS, uid, sizeof(uid));

            if (g_dbglevel >= DBG_EXTENDED) {
                Dbprintf("[+] %d bytes read from IDENTIFY request:", recvlen);
                DbdecodeIso15693Answer(recvlen, answer);
                Dbhexdump(recvlen, answer, true);
            }
        } else {
            p_card->uidlen = 0;
            DbpString("Failed to select card");
            reply_ng(CMD_HF_ISO15693_READER, PM3_EFAILED, NULL, 0);
        }
    }
    switch_off();
    BigBuf_free();
}

// When SIM: initialize the Proxmark3 as ISO15693 tag
void Iso15693InitTag(void) {

    FpgaDownloadAndGo(FPGA_BITSTREAM_HF_15);

    // Start from off (no field generated)
    FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
    LEDsoff();
    SpinDelay(10);

    // switch simulation FPGA
    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);

    // initialize SSC and select proper AD input
    FpgaSetupSsc(FPGA_MAJOR_MODE_HF_SIMULATOR);
    SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

    clear_trace();
    set_tracing(true);

    StartCountSspClk();
}

void EmlClearIso15693(void) {
    // Resetting the bitstream also frees the BigBuf memory, so we do this here to prevent
    // an inconvenient reset in the future by Iso15693InitTag
    FpgaDownloadAndGo(FPGA_BITSTREAM_HF_15);
    BigBuf_Clear_EM();
    reply_ng(CMD_HF_ISO15693_EML_CLEAR, PM3_SUCCESS, NULL, 0);
}

// Simulate an ISO15693 TAG, perform anti-collision and then print any reader commands
// all demodulation performed in arm rather than host. - greg
void SimTagIso15693(uint8_t *uid, uint8_t block_size) {

    // free eventually allocated BigBuf memory
    BigBuf_free_keep_EM();
    // Init early to be sure FPGA is loaded before any EML operation
    // usefull when eml memory is empty (UID supplied)
    Iso15693InitTag(); // to be sure FPGA is loaded before any EML operation

    iso15_tag_t *tag = (iso15_tag_t *) BigBuf_get_EM_addr();
    if (tag == NULL) {
        Dbprintf("Can't allocate emulator memory");
        reply_ng(CMD_HF_ISO15693_SIMULATE, PM3_EFAILED, NULL, 0);
        return;
    }

    if (uid != NULL) {

        uint8_t empty[8] = { 0 };

        // User supplied not empty?
        if (memcmp(uid, empty, 8)) {
            // Set default values if user supplied a UID.
            // Assume emulator memory is empty
            tag->uid[0] = uid[7]; // always E0
            tag->uid[1] = uid[6]; // IC Manufacturer code
            tag->uid[2] = uid[5];
            tag->uid[3] = uid[4];
            tag->uid[4] = uid[3];
            tag->uid[5] = uid[2];
            tag->uid[6] = uid[1];
            tag->uid[7] = uid[0];

            tag->dsfid = 0;
            tag->dsfidLock = false;
            tag->afi = 0;
            tag->afiLock = false;
            tag->bytesPerPage = (block_size > 0) ? block_size : 4;
            tag->pagesCount = 64;
            tag->ic = 0;
            memset(tag->locks, 0, sizeof(tag->locks));
            memset(tag->data, 0, sizeof(tag->data));
        }
    }

    if ((tag->pagesCount > ISO15693_TAG_MAX_PAGES) ||
            ((tag->pagesCount * tag->bytesPerPage) > ISO15693_TAG_MAX_SIZE) ||
            (tag->pagesCount == 0) ||
            (tag->bytesPerPage == 0)) {
        Dbprintf("Tag size error: pagesCount = %d, bytesPerPage=%d", tag->pagesCount, tag->bytesPerPage);
        reply_ng(CMD_HF_ISO15693_SIMULATE, PM3_EOPABORTED, NULL, 0);
        return;
    }

    LED_A_ON();

    if (g_dbglevel >= DBG_DEBUG) {
        Dbprintf("ISO-15963 Simulating uid: %02X%02X%02X%02X%02X%02X%02X%02X,  %u bytes/blocks x %u blocks"
                 , tag->uid[7]
                 , tag->uid[6]
                 , tag->uid[5]
                 , tag->uid[4]
                 , tag->uid[3]
                 , tag->uid[2]
                 , tag->uid[1]
                 , tag->uid[0]
                 , tag->bytesPerPage
                 , tag->pagesCount
                );
    }

    LED_C_ON();

    bool button_pressed = false;
    int vHf; // in mV

    bool exit_loop = false;
    uint8_t cmd[ISO15693_MAX_COMMAND_LENGTH] = {0};
    uint8_t recv[ISO15693_MAX_RESPONSE_LENGTH] = {0};
    uint8_t mask_len = 0;
    uint8_t maskCpt = 0;
    uint8_t cmdCpt = 0;
    uint16_t recvLen = 0;
    uint8_t error = 0;
    uint8_t pageNum = 0;
    uint8_t nbPages = 0;
    uint8_t pwdId = 0;

    while (exit_loop == false) {

        button_pressed = BUTTON_PRESS();
        if (button_pressed || data_available())
            break;

        WDT_HIT();

        // find reader field
        if (tag->state == TAG_STATE_NO_FIELD) {

            vHf = (MAX_ADC_HF_VOLTAGE * SumAdc(ADC_CHAN_HF, 32)) >> 15;
            if (vHf > MF_MINFIELDV) {
                tag->state = TAG_STATE_READY;
                LED_A_ON();
            } else {
                continue;
            }
        }

        // Listen to reader
        uint32_t reader_eof_time = 0;
        int cmd_len = GetIso15693CommandFromReader(cmd, sizeof(cmd), &reader_eof_time);
        if (cmd_len < 0) {
            button_pressed = true;
            break;
        }

        if (cmd_len <= 3)
            continue;

        // Shorten 0 terminated msgs
        // (Some times received commands are prolonged with a random number of 0 bytes...)
        while (cmd[cmd_len - 1] == 0) {
            cmd_len--;
            if (cmd_len <= 3)
                break;
        }

        if (g_dbglevel >= DBG_DEBUG) {
            Dbprintf("%d bytes read from reader:", cmd_len);
            Dbhexdump(cmd_len, cmd, false);
        }

        if (cmd_len < 3)
            continue;

        // Check CRC and drop received cmd with bad CRC
        uint16_t crc = CalculateCrc15(cmd, cmd_len - 2);
        if (((crc & 0xff) != cmd[cmd_len - 2]) || ((crc >> 8) != cmd[cmd_len - 1])) {
            crc = CalculateCrc15(cmd, ++cmd_len - 2); // if crc end with 00
            if (((crc & 0xff) != cmd[cmd_len - 2]) || ((crc >> 8) != cmd[cmd_len - 1])) {
                crc = CalculateCrc15(cmd, ++cmd_len - 2); // if crc end with 00 00
                if (((crc & 0xff) != cmd[cmd_len - 2]) || ((crc >> 8) != cmd[cmd_len - 1])) {
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("CrcFail!, expected CRC=%02X%02X", crc & 0xff, crc >> 8);
                    continue;
                } else if (g_dbglevel >= DBG_DEBUG)
                    Dbprintf("CrcOK");
            } else if (g_dbglevel >= DBG_DEBUG)
                Dbprintf("CrcOK");
        } else if (g_dbglevel >= DBG_DEBUG)
            Dbprintf("CrcOK");

        cmd_len -= 2; // remove the CRC from the cmd
        recvLen = 0;

        tag->expectFast = ((cmd[0] & ISO15_REQ_DATARATE_HIGH) == ISO15_REQ_DATARATE_HIGH);
        tag->expectFsk = ((cmd[0] & ISO15_REQ_SUBCARRIER_TWO) == ISO15_REQ_SUBCARRIER_TWO);

        if (g_dbglevel >= DBG_DEBUG) {
            if (tag->expectFsk)
                Dbprintf("ISO15_REQ_SUBCARRIER_TWO support is currently experimental!");
            if ((cmd[0] & ISO15_REQ_PROTOCOL_EXT) == ISO15_REQ_PROTOCOL_EXT)
                Dbprintf("ISO15_REQ_PROTOCOL_EXT not supported!");
            if ((cmd[0] & ISO15_REQ_OPTION) == ISO15_REQ_OPTION)
                Dbprintf("ISO15_REQ_OPTION not supported!");
        }

        if (((cmd[0] & ISO15_REQ_INVENTORY) == ISO15_REQ_INVENTORY) && tag->state != TAG_STATE_SILENCED) {
            // REQ_INVENTORY flaged requests are interpreted as a INVENTORY no matter
            // what is the CMD (as observed from various actual tags)

            // TODO: support colision avoidances

            if (g_dbglevel >= DBG_DEBUG) {
                Dbprintf("Inventory req");
                if ((cmd[0] & ISO15_REQINV_SLOT1) == ISO15_REQINV_SLOT1)
                    Dbprintf("ISO15_REQINV_SLOT1/SLOT16 not supported!");
            }

            cmdCpt = 2;

            // Check AFI
            if ((cmd[0] & ISO15_REQINV_AFI) == ISO15_REQINV_AFI) {
                if (cmd[cmdCpt] != tag->afi && cmd[cmdCpt] != 0)
                    continue; // bad AFI : drop request
                cmdCpt++;
            }

            // Check mask
            if (cmdCpt >= cmd_len)
                continue; // mask is not present : drop request
            mask_len = cmd[cmdCpt++];

            maskCpt = 0;

            while (mask_len >= 8 && cmdCpt < (uint8_t)cmd_len && maskCpt < 8) { // Byte comparison
                if (cmd[cmdCpt++] != tag->uid[maskCpt++]) {
                    error++; // mask don't match : drop request
                    break;
                }
                mask_len -= 8;
            }

            if (mask_len > 0 && cmdCpt >= cmd_len)
                continue; // mask is shorter than declared mask lenght: drop request

            while (mask_len > 0) { // Bit comparison
                mask_len--;
                if (((cmd[cmdCpt] >> mask_len) & 1) != ((tag->uid[maskCpt] >> mask_len) & 1)) {
                    error++; // mask don't match : drop request
                    break;
                }
            }

            if (error > 0)
                continue;

            // No error: Answer
            recv[0] = ISO15_NOERROR;
            recv[1] = tag->dsfid;
            memcpy(&recv[2], tag->uid, 8);
            recvLen = 10;
        } else {
            if ((cmd[0] & ISO15_REQ_SELECT) == ISO15_REQ_SELECT) {
                if (g_dbglevel >= DBG_DEBUG) Dbprintf("Selected Request");
                if (tag->state != TAG_STATE_SELECTED)
                    continue; // drop selected request if not selected
                tag->state = TAG_STATE_READY; // Select flag set if already selected : unselect
            }

            cmdCpt = 2;
            if ((cmd[0] & ISO15_REQ_ADDRESS) == ISO15_REQ_ADDRESS) {
                if (g_dbglevel >= DBG_DEBUG) Dbprintf("Addressed Request");
                if (cmd_len < cmdCpt + 8)
                    continue;
                if (memcmp(&cmd[cmdCpt], tag->uid, 8) != 0) {
                    if (cmd_len < cmdCpt + 9 ||  memcmp(&cmd[cmdCpt + 1], tag->uid, 8) != 0) {
                        // check uid even if manifacturer byte is present
                        if (g_dbglevel >= DBG_DEBUG) Dbprintf("Address don't match tag uid");
                        if (cmd[1] == ISO15693_SELECT)
                            tag->state = TAG_STATE_READY; // we are not anymore the selected TAG
                        continue; // drop addressed request with other uid
                    }
                    cmdCpt++;
                }
                if (g_dbglevel >= DBG_DEBUG) Dbprintf("Address match tag uid");
                cmdCpt += 8;
            } else if (tag->state == TAG_STATE_SILENCED) {
                if (g_dbglevel >= DBG_DEBUG) Dbprintf("Unaddressed request in quiet state: drop");
                continue; // drop unadressed request in quiet state
            }

            switch (cmd[1]) {
                case ISO15693_INVENTORY:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("Inventory cmd");
                    recv[0] = ISO15_NOERROR;
                    recv[1] = tag->dsfid;
                    memcpy(&recv[2], tag->uid, 8);
                    recvLen = 10;
                    break;
                case ISO15693_STAYQUIET:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("StayQuiet cmd");
                    tag->state = TAG_STATE_SILENCED;
                    break;
                case ISO15693_READBLOCK:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("ReadBlock cmd");
                    pageNum = cmd[cmdCpt++];
                    if (pageNum >= tag->pagesCount)
                        error = ISO15_ERROR_BLOCK_UNAVAILABLE;
                    else {
                        recv[0] = ISO15_NOERROR;
                        recvLen = 1;
                        if ((cmd[0] & ISO15_REQ_OPTION) == ISO15_REQ_OPTION) { // ask for lock status
                            recv[1] = tag->locks[pageNum];
                            recvLen++;
                        }
                        for (uint8_t i = 0 ; i < tag->bytesPerPage ; i++)
                            recv[recvLen + i] = tag->data[(pageNum * tag->bytesPerPage) + i];
                        recvLen += tag->bytesPerPage;
                    }
                    break;
                case ISO15693_WRITEBLOCK:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("WriteBlock cmd");
                    pageNum = cmd[cmdCpt++];
                    if (pageNum >= tag->pagesCount)
                        error = ISO15_ERROR_BLOCK_UNAVAILABLE;
                    else {
                        for (uint8_t i = 0 ; i < tag->bytesPerPage ; i++)
                            tag->data[(pageNum * tag->bytesPerPage) + i] = cmd[i + cmdCpt];
                        recv[0] = ISO15_NOERROR;
                        recvLen = 1;
                    }
                    break;
                case ISO15693_LOCKBLOCK:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("LockBlock cmd");
                    pageNum = cmd[cmdCpt++];
                    if (pageNum >= tag->pagesCount)
                        error = ISO15_ERROR_BLOCK_UNAVAILABLE;
                    else if (tag->locks[pageNum])
                        error = ISO15_ERROR_BLOCK_LOCKED_ALREADY;
                    else {
                        tag->locks[pageNum] = 1;
                        recv[0] = ISO15_NOERROR;
                        recvLen = 1;
                    }
                    break;
                case ISO15693_READ_MULTI_BLOCK:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("ReadMultiBlock cmd");
                    pageNum = cmd[cmdCpt++];
                    nbPages = cmd[cmdCpt++];
                    if (pageNum + nbPages >= tag->pagesCount)
                        error = ISO15_ERROR_BLOCK_UNAVAILABLE;
                    else {
                        recv[0] = ISO15_NOERROR;
                        recvLen = 1;
                        for (int i = 0 ; i < (nbPages + 1) * tag->bytesPerPage && \
                                recvLen + 3 < ISO15693_MAX_RESPONSE_LENGTH ; i++) {
                            if ((i % tag->bytesPerPage) == 0 && (cmd[0] & ISO15_REQ_OPTION))
                                recv[recvLen++] = tag->locks[pageNum + (i / tag->bytesPerPage)];
                            recv[recvLen++] = tag->data[(pageNum * tag->bytesPerPage) + i];
                        }
                        if (recvLen + 3 > ISO15693_MAX_RESPONSE_LENGTH) // limit response size
                            recvLen = ISO15693_MAX_RESPONSE_LENGTH - 3; // to avoid overflow
                    }
                    break;
                case ISO15693_WRITE_AFI:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("WriteAFI cmd");
                    if (tag->afiLock)
                        error = ISO15_ERROR_BLOCK_LOCKED;
                    else {
                        tag->afi = cmd[cmdCpt++];
                        recv[0] = ISO15_NOERROR;
                        recvLen = 1;
                    }
                    break;
                case ISO15693_LOCK_AFI:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("LockAFI cmd");
                    if (tag->afiLock)
                        error = ISO15_ERROR_BLOCK_LOCKED_ALREADY;
                    else {
                        tag->afiLock = true;
                        recv[0] = ISO15_NOERROR;
                        recvLen = 1;
                    }
                    break;
                case ISO15693_WRITE_DSFID:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("WriteDSFID cmd");
                    if (tag->dsfidLock)
                        error = ISO15_ERROR_BLOCK_LOCKED;
                    else {
                        tag->dsfid = cmd[cmdCpt++];
                        recv[0] = ISO15_NOERROR;
                        recvLen = 1;
                    }
                    break;
                case ISO15693_LOCK_DSFID:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("LockDSFID cmd");
                    if (tag->dsfidLock)
                        error = ISO15_ERROR_BLOCK_LOCKED_ALREADY;
                    else {
                        tag->dsfidLock = true;
                        recv[0] = ISO15_NOERROR;
                        recvLen = 1;
                    }
                    break;
                case ISO15693_SELECT:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("Select cmd");
                    tag->state = TAG_STATE_SELECTED;
                    recv[0] = ISO15_NOERROR;
                    recvLen = 1;
                    break;
                case ISO15693_RESET_TO_READY:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("ResetToReady cmd");
                    tag->state = TAG_STATE_READY;
                    recv[0] = ISO15_NOERROR;
                    recvLen = 1;
                    break;
                case ISO15693_GET_SYSTEM_INFO:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("GetSystemInfo cmd");
                    recv[0] = ISO15_NOERROR;
                    recv[1] = 0x0f; // sysinfo contain all info
                    memcpy(&recv[2], tag->uid, 8);
                    recv[10] = tag->dsfid;
                    recv[11] = tag->afi;
                    recv[12] = tag->pagesCount - 1;
                    recv[13] = tag->bytesPerPage - 1;
                    recv[14] = tag->ic;
                    recvLen = 15;
                    break;
                case ISO15693_READ_MULTI_SECSTATUS:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("ReadMultiSecStatus cmd");
                    pageNum = cmd[cmdCpt++];
                    nbPages = cmd[cmdCpt++];
                    if (pageNum + nbPages >= tag->pagesCount)
                        error = ISO15_ERROR_BLOCK_UNAVAILABLE;
                    else {
                        recv[0] = ISO15_NOERROR;
                        recvLen = 1;
                        for (uint8_t i = 0 ; i < nbPages + 1 ; i++)
                            recv[recvLen++] = tag->locks[pageNum + i];
                    }
                    break;
                case ISO15693_GET_RANDOM_NUMBER:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("GetRandomNumber cmd");
                    tag->random[0] = (uint8_t)(reader_eof_time) ^ 0xFF; // poor random number
                    tag->random[1] = (uint8_t)(reader_eof_time >> 8) ^ 0xFF;
                    recv[0] = ISO15_NOERROR;
                    recv[1] = tag->random[0]; // poor random number
                    recv[2] = tag->random[1];
                    recvLen = 3;
                    break;
                case ISO15693_SET_PASSWORD:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("SetPassword cmd");
                    if (cmd_len > cmdCpt + 5)
                        cmdCpt++; // skip manifacturer code
                    if (cmd_len > cmdCpt + 4) {
                        pwdId = cmd[cmdCpt++];
                        if (pwdId == 4) { // Privacy password
                            tag->privacyPasswd[0] = cmd[cmdCpt] ^ tag->random[0];
                            tag->privacyPasswd[1] = cmd[cmdCpt + 1] ^ tag->random[1];
                            tag->privacyPasswd[2] = cmd[cmdCpt + 2] ^ tag->random[0];
                            tag->privacyPasswd[3] = cmd[cmdCpt + 3] ^ tag->random[1];
                        }
                    }
                    recv[0] = ISO15_NOERROR;
                    recvLen = 1;
                    break;
                case ISO15693_ENABLE_PRIVACY:
                    if (g_dbglevel >= DBG_DEBUG) Dbprintf("EnablePrivacy cmd");
                    // not realy entering privacy mode
                    // just return NOERROR
                    recv[0] = ISO15_NOERROR;
                    recvLen = 1;
                    break;
                default:
                    if (g_dbglevel >= DBG_DEBUG)
                        Dbprintf("ISO15693 CMD 0x%2X not supported", cmd[1]);

                    error = ISO15_ERROR_CMD_NOT_SUP;
                    break;
            }

            if (error != 0) { // Error happened
                recv[0] = ISO15_RES_ERROR;
                recv[1] = error;
                recvLen = 2;
                error = 0;
                if (g_dbglevel >= DBG_DEBUG)
                    Dbprintf("ERROR 0x%2X in received request", error);
            }
        }

        if (recvLen > 0) { // We need to answer
            AddCrc15(recv, recvLen);
            recvLen += 2;
            CodeIso15693AsTag(recv, recvLen);
            tosend_t *ts = get_tosend();
            uint32_t response_time = reader_eof_time + DELAY_ISO15693_VCD_TO_VICC_SIM;

            if (tag->expectFsk) { // Not suppoted yet
                if (g_dbglevel >= DBG_DEBUG) Dbprintf("%ERROR: FSK answers are not supported yet");
                //TransmitTo15693ReaderFSK(ts->buf,ts->max, &response_time, 0, !tag->expectFast);
            } else
                TransmitTo15693Reader(ts->buf, ts->max, &response_time, 0, !tag->expectFast);

            LogTrace_ISO15693(recv, recvLen, response_time * 32, (response_time * 32) + (ts->max * 32 * 64), NULL, false);
        }
    }

    switch_off();

    if (button_pressed) {
        DbpString("button pressed");
    }

    reply_ng(CMD_HF_ISO15693_SIMULATE, PM3_SUCCESS, NULL, 0);
}

// Since there is no standardized way of reading the AFI out of a tag, we will brute force it
// (some manufactures offer a way to read the AFI, though)
void BruteforceIso15693Afi(uint32_t flags) {

    clear_trace();

    Iso15693InitReader();

    bool speed = ((flags & ISO15_HIGH_SPEED) == ISO15_HIGH_SPEED);

    // first without AFI
    // Tags should respond without AFI and with AFI=0 even when AFI is active
    uint8_t data[7] = {0};
    uint8_t recv[ISO15693_MAX_RESPONSE_LENGTH] = {0};

    data[0] = (ISO15_REQ_SUBCARRIER_SINGLE | ISO15_REQ_DATARATE_HIGH | ISO15_REQ_INVENTORY | ISO15_REQINV_SLOT1);
    data[1] = ISO15693_INVENTORY;
    data[2] = 0; // AFI
    AddCrc15(data, 3);

    int datalen = 5;
    uint32_t eof_time = 0;
    uint16_t recvlen = 0;
    int res = SendDataTag(data, datalen, true, speed, recv, sizeof(recv), 0, ISO15693_READER_TIMEOUT, &eof_time, &recvlen);
    if (res != PM3_SUCCESS) {
        DbpString("Failed to select card");
        reply_ng(CMD_HF_ISO15693_FINDAFI, res, NULL, 0);
        switch_off();
        return;
    }

    uint32_t start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    WDT_HIT();

    if (recvlen >= 12) {
        Dbprintf("NoAFI UID = %s", iso15693_sprintUID(NULL, recv + 2));
    }

    // now with AFI
    data[0] |= ISO15_REQINV_AFI;
    data[2] = 0; // AFI
    data[3] = 0; // mask length

    // 4 + 2crc
    datalen = 6;

    bool aborted = false;
    for (uint16_t i = 0; i < 256; i++) {

        data[2] = i & 0xFF;
        AddCrc15(data, 4);

        recvlen = 0;
        res = SendDataTag(data, datalen, false, speed, recv, sizeof(recv), start_time, ISO15693_READER_TIMEOUT, &eof_time, &recvlen);
        start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;

        WDT_HIT();

        if (recvlen >= 12) {
            Dbprintf("AFI = %i  UID = %s", i, iso15693_sprintUID(NULL, recv + 2));
        }

        aborted = (BUTTON_PRESS() && data_available());
        if (aborted) {
            break;
        }
    }

    DbpString("AFI Bruteforcing done.");
    switch_off();

    if (aborted) {
        reply_ng(CMD_HF_ISO15693_FINDAFI, PM3_EOPABORTED, NULL, 0);
    } else {
        reply_ng(CMD_HF_ISO15693_FINDAFI, PM3_SUCCESS, NULL, 0);
    }
}

// Allows to directly send commands to the tag via the client
// OBS:  doesn't turn off rf field afterwards.
void SendRawCommand15693(iso15_raw_cmd_t *packet) {

    LED_A_ON();

    uint16_t timeout = ISO15693_READER_TIMEOUT;
    if ((packet->flags & ISO15_LONG_WAIT) == ISO15_LONG_WAIT) {
        timeout = ISO15693_READER_TIMEOUT_WRITE;
    }

    bool speed = ((packet->flags & ISO15_HIGH_SPEED) == ISO15_HIGH_SPEED);
    bool keep_field_on = ((packet->flags & ISO15_NO_DISCONNECT) == ISO15_NO_DISCONNECT);
    bool read_respone = ((packet->flags & ISO15_READ_RESPONSE) == ISO15_READ_RESPONSE);
    bool init = ((packet->flags & ISO15_CONNECT) == ISO15_CONNECT);

    // This is part of ISO15693 protocol definitions where the following commands needs to request option.
    // note:
    //     it seem like previous we just guessed and never followed the fISO145_REQ_OPTION flag if it was set / not set from client side.
    //     this is a problem.   Since without this the response from the tag is one byte shorter.   And a lot of client side functions has been
    //     hardcoded to assume for the extra byte in the response.

    bool request_answer = false;

    switch (packet->raw[1]) {
        case ISO15693_SET_PASSWORD:
        case ISO15693_ENABLE_PRIVACY:
        case ISO15693_WRITEBLOCK:
        case ISO15693_LOCKBLOCK:
        case ISO15693_WRITE_MULTI_BLOCK:
        case ISO15693_WRITE_AFI:
        case ISO15693_LOCK_AFI:
        case ISO15693_WRITE_DSFID:
        case ISO15693_WRITE_PASSWORD:
        case ISO15693_PASSWORD_PROTECT_EAS:
        case ISO15693_LOCK_DSFID:
            request_answer = ((packet->raw[0] & ISO15_REQ_OPTION) == ISO15_REQ_OPTION);
            break;
        default:
            break;
    }

    uint32_t eof_time = 0;
    uint32_t start_time = 0;
    uint16_t recvlen = 0;

    uint8_t buf[ISO15693_MAX_RESPONSE_LENGTH] = {0x00};

    int res = SendDataTag(packet->raw, packet->rawlen, init, speed, (read_respone ? buf : NULL), sizeof(buf), start_time, timeout, &eof_time, &recvlen);

    if (res == PM3_ETEAROFF) { // tearoff occurred
        reply_ng(CMD_HF_ISO15693_COMMAND, res, NULL, 0);
    } else {

        // if tag answers with an error code,  it don't care about EOF packet
        if (recvlen) {
            recvlen = MIN(recvlen, ISO15693_MAX_RESPONSE_LENGTH);
            reply_ng(CMD_HF_ISO15693_COMMAND, res, buf, recvlen);
        }

        // looking at the first byte of the RAW bytes to determine Subcarrier, datarate, request option
        bool fsk = ((packet->raw[0] & ISO15_REQ_SUBCARRIER_TWO) == ISO15_REQ_SUBCARRIER_TWO);
        bool recv_speed = ((packet->raw[0] & ISO15_REQ_DATARATE_HIGH) == ISO15_REQ_DATARATE_HIGH);

        // send a single EOF to get the tag response
        if (request_answer) {
            start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
            res = SendDataTagEOF((read_respone ? buf : NULL), sizeof(buf), start_time, ISO15693_READER_TIMEOUT, &eof_time, fsk, recv_speed, &recvlen);
        }

        if (read_respone) {
            recvlen = MIN(recvlen, ISO15693_MAX_RESPONSE_LENGTH);
            reply_ng(CMD_HF_ISO15693_COMMAND, res, buf, recvlen);
        } else {
            reply_ng(CMD_HF_ISO15693_COMMAND, PM3_SUCCESS, NULL, 0);
        }
    }

    if (keep_field_on == false) {
        switch_off(); // disconnect raw
        SpinDelay(20);
    }

    LED_A_OFF();
}

/*
SLIx functions from official master forks.

void LockPassSlixIso15693(uint32_t pass_id, uint32_t password) {

    LED_A_ON();

    uint8_t cmd_inventory[]  = {ISO15693_REQ_DATARATE_HIGH | ISO15693_REQ_INVENTORY | ISO15693_REQINV_SLOT1, 0x01, 0x00, 0x00, 0x00 };
    uint8_t cmd_get_rnd[]    = {ISO15693_REQ_DATARATE_HIGH, 0xB2, 0x04, 0x00, 0x00 };
    uint8_t cmd_set_pass[]   = {ISO15693_REQ_DATARATE_HIGH, 0xB3, 0x04, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
    //uint8_t cmd_write_pass[] = {ISO15693_REQ_DATARATE_HIGH | ISO15693_REQ_ADDRESS, 0xB4, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
    uint8_t cmd_lock_pass[] = {ISO15693_REQ_DATARATE_HIGH | ISO15693_REQ_ADDRESS, 0xB5, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00 };
    uint16_t crc;
    uint16_t recvlen = 0;
    uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
    uint32_t start_time = 0;
    bool done = false;
    int res;

    // setup 'get random number' command
    crc = Iso15693Crc(cmd_get_rnd, 3);
    cmd_get_rnd[3] = crc & 0xff;
    cmd_get_rnd[4] = crc >> 8;

    Dbprintf("LockPass: Press button lock password, long-press to terminate.");

    while (!done) {

        LED_D_ON();
        switch(BUTTON_HELD(1000)) {
            case BUTTON_SINGLE_CLICK:
                Dbprintf("LockPass: Reset 'DONE'-LED (A)");
                LED_A_OFF();
                LED_B_OFF();
                LED_C_OFF();
                break;
            case BUTTON_HOLD:
                Dbprintf("LockPass: Terminating");
                done = true;
                break;
            default:
                SpinDelay(50);
                continue;
        }

        if (done) [
            break;
        }

        res = SendDataTag(cmd_get_rnd, sizeof(cmd_get_rnd), true, true, recvbuf, sizeof(recvbuf), start_time, &recvlen);
        if (res != PM3_SUCCESS && recvlen != 5) {
            LED_C_ON();
        } else {
            Dbprintf("LockPass: Received random 0x%02X%02X (%d)", recvbuf[1], recvbuf[2], recvlen);

            // setup 'set password' command
            cmd_set_pass[4] = ((password>>0) &0xFF) ^ recvbuf[1];
            cmd_set_pass[5] = ((password>>8) &0xFF) ^ recvbuf[2];
            cmd_set_pass[6] = ((password>>16) &0xFF) ^ recvbuf[1];
            cmd_set_pass[7] = ((password>>24) &0xFF) ^ recvbuf[2];

            crc = Iso15693Crc(cmd_set_pass, 8);
            cmd_set_pass[8] = crc & 0xff;
            cmd_set_pass[9] = crc >> 8;

            Dbprintf("LockPass: Sending old password to end privacy mode", cmd_set_pass[4], cmd_set_pass[5], cmd_set_pass[6], cmd_set_pass[7]);
            res = SendDataTag(cmd_set_pass, sizeof(cmd_set_pass), false, true, recvbuf, sizeof(recvbuf), start_time, &recvlen);
            if (res != PM3_SUCCESS && recvlen != 3) {
                Dbprintf("LockPass: Failed to set password (%d)", recvlen);
                LED_B_ON();
            } else {
                crc = Iso15693Crc(cmd_inventory, 3);
                cmd_inventory[3] = crc & 0xff;
                cmd_inventory[4] = crc >> 8;

                Dbprintf("LockPass: Searching for tag...");
                res = SendDataTag(cmd_inventory, sizeof(cmd_inventory), false, true, recvbuf, sizeof(recvbuf), start_time, &recvlen);
                if (res != PM3_SUCCESS && recvlen != 12) {
                    Dbprintf("LockPass: Failed to read inventory (%d)", recvlen);
                    LED_B_ON();
                    LED_C_ON();
                } else {

                    Dbprintf("LockPass: Answer from %02X%02X%02X%02X%02X%02X%02X%02X", recvbuf[9], recvbuf[8], recvbuf[7], recvbuf[6], recvbuf[5], recvbuf[4], recvbuf[3], recvbuf[2]);

                    memcpy(&cmd_lock_pass[3], &recvbuf[2], 8);

                    cmd_lock_pass[8+3] = pass_id;

                    crc = Iso15693Crc(cmd_lock_pass, 8+4);
                    cmd_lock_pass[8+4] = crc & 0xff;
                    cmd_lock_pass[8+5] = crc >> 8;

                    Dbprintf("LockPass: locking to password 0x%02X%02X%02X%02X for ID %02X", cmd_set_pass[4], cmd_set_pass[5], cmd_set_pass[6], cmd_set_pass[7], pass_id);

                    res = SendDataTag(cmd_lock_pass, sizeof(cmd_lock_pass), false, true, recvbuf, sizeof(recvbuf), start_time, &recvlen);
                    if (res != PM3_SUCCESS && recvlen != 3) {
                        Dbprintf("LockPass: Failed to lock password (%d)", recvlen);
                    } else {
                        Dbprintf("LockPass: Successful (%d)", recvlen);
                    }
                    LED_A_ON();
                }
            }       }
    }

    Dbprintf("LockPass: Finishing");
    cmd_send(CMD_ACK, recvlen, 0, 0, recvbuf, recvlen);
}
*/

//-----------------------------------------------------------------------------
// Work with "magic Chinese" card.
//
//-----------------------------------------------------------------------------

// Set the UID on Magic ISO15693 tag (based on Iceman's LUA-script).
void SetTag15693Uid(const uint8_t *uid) {

    LED_A_ON();
    uint8_t cmd[4][9] = {
        {ISO15_REQ_DATARATE_HIGH, ISO15693_WRITEBLOCK, 0x3e, 0x00, 0x00, 0x00, 0x00, 0xE9, 0x8F},
        {ISO15_REQ_DATARATE_HIGH, ISO15693_WRITEBLOCK, 0x3f, 0x69, 0x96, 0x00, 0x00, 0x8A, 0xBB},

        // Command 3 : 02 21 38 u8u7u6u5 (where uX = uid byte X)
        {ISO15_REQ_DATARATE_HIGH, ISO15693_WRITEBLOCK, 0x38, uid[7], uid[6], uid[5], uid[4]},

        // Command 4 : 02 21 39 u4u3u2u1 (where uX = uid byte X)
        {ISO15_REQ_DATARATE_HIGH, ISO15693_WRITEBLOCK, 0x39, uid[3], uid[2], uid[1], uid[0]}
    };


    AddCrc15(cmd[2], 7);
    AddCrc15(cmd[3], 7);

    uint8_t buf[ISO15693_MAX_RESPONSE_LENGTH] = {0x00};

    uint32_t start_time = 0;
    uint32_t eof_time = 0;
    uint16_t recvlen = 0;

    int res = PM3_SUCCESS;

    for (int i = 0; i < 4; i++) {
        res = SendDataTag(
                  cmd[i],
                  sizeof(cmd[i]),
                  (i == 0) ? true : false,
                  true,
                  buf,
                  sizeof(buf),
                  start_time,
                  ISO15693_READER_TIMEOUT_WRITE,
                  &eof_time,
                  &recvlen
              );

        start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    }

    reply_ng(CMD_HF_ISO15693_CSETUID, res, NULL, 0);
    switch_off();
}

// Set the UID on Magic ISO15693 tag ( Gen2 ?)
// E0 00 09   - seem to be command
// 0x41, 0x40 - seem to be block referens
void SetTag15693Uid_v2(const uint8_t *uid) {

    LED_A_ON();
    uint8_t cmd[4][10] = {
        { ISO15_REQ_DATARATE_HIGH, ISO15693_MAGIC_WRITE, 0x09, 0x47, 0x3f, 0x03, 0x8b, 0x00,  0x00, 0x00 },
        { ISO15_REQ_DATARATE_HIGH, ISO15693_MAGIC_WRITE, 0x09, 0x52, 0x00, 0x00, 0x00, 0x00,  0x00, 0x00 },
        // hf 15 raw -wac -d 02 e0 09 41 + uid first four bytes
        {ISO15_REQ_DATARATE_HIGH, ISO15693_MAGIC_WRITE, 0x09, 0x41, uid[7], uid[6], uid[5], uid[4], 0x00, 0x00},
        // hf 15 raw -wac -d 02 e0 09 40 + uid last four bytes
        {ISO15_REQ_DATARATE_HIGH, ISO15693_MAGIC_WRITE, 0x09, 0x40, uid[3], uid[2], uid[1], uid[0], 0x00, 0x00}
    };

    uint8_t buf[ISO15693_MAX_RESPONSE_LENGTH] = {0x00};

    uint32_t start_time = 0;
    uint32_t eof_time = 0;
    uint16_t recvlen = 0;

    int res = PM3_SUCCESS;

    for (int i = 0; i < 4; i++) {

        AddCrc15(cmd[i], 8);
        res = SendDataTag(
                  cmd[i],
                  sizeof(cmd[i]),
                  (i == 0) ? true : false,
                  true,
                  buf,
                  sizeof(buf),
                  start_time,
                  ISO15693_READER_TIMEOUT_WRITE,
                  &eof_time,
                  &recvlen
              );

        start_time = eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    }

    reply_ng(CMD_HF_ISO15693_CSETUID_V2, res, NULL, 0);
    switch_off();
}


static void init_password_15693_Slix(uint8_t *buffer, const uint8_t *pwd, const uint8_t *rnd) {
    memcpy(buffer, pwd, 4);
    if (rnd) {
        buffer[0] ^= rnd[0];
        buffer[1] ^= rnd[1];
        buffer[2] ^= rnd[0];
        buffer[3] ^= rnd[1];
    }
}

static bool get_rnd_15693_Slix(uint32_t start_time, uint32_t *eof_time, uint8_t *rnd) {
    // 0x04, == NXP from manufacture id list.
    uint8_t c[] = {ISO15_REQ_DATARATE_HIGH, ISO15693_GET_RANDOM_NUMBER, 0x04, 0x00, 0x00 };
    AddCrc15(c, 3);

    uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
    uint16_t recvlen = 0;
    int res = SendDataTag(c, sizeof(c), true, true, recvbuf, sizeof(recvbuf), start_time, ISO15693_READER_TIMEOUT_WRITE, eof_time, &recvlen);
    if (res != PM3_SUCCESS && recvlen != 5) {
        return false;
    }

    if (rnd) {
        memcpy(rnd, &recvbuf[1], 2);
    }
    return true;
}

static uint32_t disable_privacy_15693_Slix(uint32_t start_time, uint32_t *eof_time, uint8_t pass_id, const uint8_t *password) {

    uint8_t rnd[2];
    if (get_rnd_15693_Slix(start_time, eof_time, rnd) == false) {
        return PM3_ETIMEOUT;
    }

    // 0x04, == NXP from manufacture id list.
    uint8_t c[] = { ISO15_REQ_DATARATE_HIGH, ISO15693_SET_PASSWORD, 0x04, pass_id, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
    init_password_15693_Slix(&c[4], password, rnd);
    AddCrc15(c, 8);

    start_time = *eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
    uint16_t recvlen = 0;
    int res = SendDataTag(c, sizeof(c), false, true, recvbuf, sizeof(recvbuf), start_time, ISO15693_READER_TIMEOUT_WRITE, eof_time, &recvlen);
    if (res != PM3_SUCCESS && recvlen != 3) {
        return PM3_EWRONGANSWER;
    }
    return PM3_SUCCESS;
}

static uint32_t set_pass_15693_Slix(uint32_t start_time, uint32_t *eof_time, uint8_t pass_id, const uint8_t *password, uint8_t *uid) {


    uint8_t rnd[2];
    if (get_rnd_15693_Slix(start_time, eof_time, rnd) == false) {
        return PM3_ETIMEOUT;
    }

    // 0x04, == NXP from manufacture id list.
    uint8_t c[] = { (ISO15_REQ_DATARATE_HIGH | ISO15_REQ_ADDRESS), ISO15693_SET_PASSWORD, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, pass_id, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };

    init_password_15693_Slix(&c[12], password, rnd);

    memcpy(&c[3], uid, 8);
    AddCrc15(c, 16);

    start_time = *eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
    uint16_t recvlen = 0;

    int res = SendDataTag(c, sizeof(c), false, true, recvbuf, sizeof(recvbuf), start_time, ISO15693_READER_TIMEOUT_WRITE, eof_time, &recvlen);
    if (res != PM3_SUCCESS && recvlen != 3) {
        return PM3_EWRONGANSWER;
    }
    return PM3_SUCCESS;
}

static uint32_t set_privacy_15693_Slix(uint32_t start_time, uint32_t *eof_time, const uint8_t *password) {
    uint8_t rnd[2];
    if (get_rnd_15693_Slix(start_time, eof_time, rnd) == false) {
        return PM3_ETIMEOUT;
    }

    // 0x04, == NXP from manufacture id list.
    uint8_t c[] = { ISO15_REQ_DATARATE_HIGH, 0xBA, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
    init_password_15693_Slix(&c[3], password, rnd);
    AddCrc15(c, 7);

    start_time = *eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
    uint16_t recvlen = 0;
    int res = SendDataTag(c, sizeof(c), false, true, recvbuf, sizeof(recvbuf), start_time, ISO15693_READER_TIMEOUT_WRITE, eof_time, &recvlen);
    if (res != PM3_SUCCESS && recvlen != 3) {
        return PM3_EWRONGANSWER;
    }
    return PM3_SUCCESS;
}

static uint32_t disable_eas_15693_Slix(uint32_t start_time, uint32_t *eof_time, const uint8_t *password, bool usepwd) {

    uint8_t uid[8];
    get_uid_slix(start_time, eof_time, uid);

    uint8_t rnd[2];
    if (get_rnd_15693_Slix(start_time, eof_time, rnd) == false) {
        return PM3_ETIMEOUT;
    }

    if (usepwd) {

        int res_setpass = set_pass_15693_Slix(start_time, eof_time, 0x10, password, uid);

        if (res_setpass != PM3_SUCCESS) {
            return PM3_EWRONGANSWER;
        }
    }

    // 0x04, == NXP from manufacture id list.
    uint8_t c[] = { ISO15_REQ_DATARATE_HIGH, 0xA3, 0x04, 0x00, 0x00};
    AddCrc15(c, 3);

    start_time = *eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
    uint16_t recvlen = 0;
    int res = SendDataTag(c, sizeof(c), false, true, recvbuf, sizeof(recvbuf), start_time, ISO15693_READER_TIMEOUT_WRITE, eof_time, &recvlen);
    if (res != PM3_SUCCESS && recvlen != 3) {
        return PM3_EWRONGANSWER;
    }
    return PM3_SUCCESS;
}

static uint32_t enable_eas_15693_Slix(uint32_t start_time, uint32_t *eof_time, const uint8_t *password, bool usepwd) {

    uint8_t uid[8];
    get_uid_slix(start_time, eof_time, uid);

    uint8_t rnd[2];
    if (get_rnd_15693_Slix(start_time, eof_time, rnd) == false) {
        return PM3_ETIMEOUT;
    }

    if (usepwd) {
        int res_setpass = set_pass_15693_Slix(start_time, eof_time, 0x10, password, uid);

        if (res_setpass != PM3_SUCCESS) {
            return PM3_EWRONGANSWER;
        }
    }
    // 0x04, == NXP from manufacture id list.
    uint8_t c[] = { ISO15_REQ_DATARATE_HIGH, 0xA2, 0x04, 0x00, 0x00};
    //init_password_15693_Slix(&c[3], password, rnd);
    AddCrc15(c, 3);

    start_time = *eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
    uint16_t recvlen = 0;
    int res = SendDataTag(c, sizeof(c), false, true, recvbuf, sizeof(recvbuf), start_time, ISO15693_READER_TIMEOUT_WRITE, eof_time, &recvlen);
    if (res != PM3_SUCCESS && recvlen != 3) {
        return PM3_EWRONGANSWER;
    }
    return PM3_SUCCESS;
}

static uint32_t write_password_15693_Slix(uint32_t start_time, uint32_t *eof_time, uint8_t pwd_id, const uint8_t *password, uint8_t *uid) {

    uint8_t new_pwd_cmd[] = { (ISO15_REQ_DATARATE_HIGH | ISO15_REQ_ADDRESS), ISO15693_WRITE_PASSWORD, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, pwd_id, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

    memcpy(&new_pwd_cmd[3], uid, 8);
    memcpy(&new_pwd_cmd[12], password, 4);

    AddCrc15(new_pwd_cmd, 16);

    start_time = *eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
    uint16_t recvlen = 0;

    int res_wrp = SendDataTag(new_pwd_cmd, sizeof(new_pwd_cmd), false, true, recvbuf, sizeof(recvbuf), start_time, ISO15693_READER_TIMEOUT_WRITE, eof_time, &recvlen);
    if (res_wrp != PM3_SUCCESS && recvlen != 3) {
        return PM3_EWRONGANSWER;
    }

    return PM3_SUCCESS;
}

static uint32_t pass_protect_EASAFI_15693_Slix(uint32_t start_time, uint32_t *eof_time, bool set_option_flag, const uint8_t *password) {

    uint8_t flags;

    if (set_option_flag)
        flags = ISO15_REQ_DATARATE_HIGH | ISO15_REQ_OPTION;
    else
        flags = ISO15_REQ_DATARATE_HIGH;


    uint8_t uid[8];
    get_uid_slix(start_time, eof_time, uid);

    uint8_t rnd[2];
    if (get_rnd_15693_Slix(start_time, eof_time, rnd) == false) {
        return PM3_ETIMEOUT;
    }

    int res_setpass = set_pass_15693_Slix(start_time, eof_time, 0x10, password, uid);

    if (res_setpass != PM3_SUCCESS) {
        return PM3_EWRONGANSWER;
    }

    uint8_t new_pass_protect_cmd[] = { flags, ISO15693_PASSWORD_PROTECT_EAS, 0x04, 0x00, 0x00};
    AddCrc15(new_pass_protect_cmd, 3);

    start_time = *eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
    uint16_t recvlen = 0;

    int res = SendDataTag(new_pass_protect_cmd, sizeof(new_pass_protect_cmd), false, true, recvbuf, sizeof(recvbuf), start_time, ISO15693_READER_TIMEOUT_WRITE, eof_time, &recvlen);
    if (res != PM3_SUCCESS && recvlen != 3) {
        return PM3_EWRONGANSWER;
    }

    return PM3_SUCCESS;
}

static uint32_t write_afi_15693(uint32_t start_time, uint32_t *eof_time, const uint8_t *password, bool usepwd, uint8_t *uid, bool use_uid, uint8_t afi) {

    if (!use_uid) {
        int res_getuid = get_uid_slix(start_time, eof_time, uid);

        if (res_getuid != PM3_SUCCESS) {
            return res_getuid;
        }
    }

    if (usepwd) {
        int res_setpass = set_pass_15693_Slix(start_time, eof_time, 0x10, password, uid);

        if (res_setpass != PM3_SUCCESS) {
            return PM3_EWRONGANSWER;
        }
    }

    uint8_t cmd[] = { ISO15_REQ_DATARATE_HIGH | ISO15_REQ_ADDRESS, ISO15693_WRITE_AFI, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

    memcpy(&cmd[2], uid, 8);
    cmd[10] = afi;
    AddCrc15(cmd, 11);

    start_time = *eof_time + DELAY_ISO15693_VICC_TO_VCD_READER;
    uint8_t recvbuf[ISO15693_MAX_RESPONSE_LENGTH];
    uint16_t recvlen = 0;

    int res = SendDataTag(cmd, sizeof(cmd), false, true, recvbuf, sizeof(recvbuf), start_time, ISO15693_READER_TIMEOUT_WRITE, eof_time, &recvlen);
    if (res != PM3_SUCCESS || recvlen != 3) {
        return PM3_EWRONGANSWER;
    }

    return PM3_SUCCESS;
}

void WritePasswordSlixIso15693(const uint8_t *old_password, const uint8_t *new_password, uint8_t pwd_id) {
    LED_D_ON();
    Iso15693InitReader();
    StartCountSspClk();
    uint32_t start_time = 0, eof_time = 0;
    int res = PM3_EFAILED;

    uint8_t uid[8];
    get_uid_slix(start_time, &eof_time, uid);

    res = set_pass_15693_Slix(start_time, &eof_time, pwd_id, old_password, uid);
    if (res != PM3_SUCCESS) {
        reply_ng(CMD_HF_ISO15693_SLIX_WRITE_PWD, res, NULL, 0);
        switch_off();
        return;
    }

    res = write_password_15693_Slix(start_time, &eof_time, pwd_id, new_password, uid);

    reply_ng(CMD_HF_ISO15693_SLIX_WRITE_PWD, res, NULL, 0);

    switch_off();

}

void DisablePrivacySlixIso15693(const uint8_t *password) {
    LED_D_ON();
    Iso15693InitReader();
    StartCountSspClk();
    uint32_t start_time = 0, eof_time = 0;

    // Password identifier Password byte
    // 0x04  Privacy
    // 0x08  Destroy SLIX-L
    // 0x10  EAS/AFI
    int res = disable_privacy_15693_Slix(start_time, &eof_time, 0x04, password);
    reply_ng(CMD_HF_ISO15693_SLIX_DISABLE_PRIVACY, res, NULL, 0);
    switch_off();
}

void EnablePrivacySlixIso15693(const uint8_t *password) {
    LED_D_ON();
    Iso15693InitReader();
    StartCountSspClk();
    uint32_t start_time = 0, eof_time = 0;

    // Password identifier Password byte
    // 0x04  Privacy
    // 0x08  Destroy SLIX-L
    // 0x10  EAS/AFI
    int res = set_privacy_15693_Slix(start_time, &eof_time, password);
    reply_ng(CMD_HF_ISO15693_SLIX_ENABLE_PRIVACY, res, NULL, 0);
    switch_off();
}


void DisableEAS_AFISlixIso15693(const uint8_t *password, bool usepwd) {
    LED_D_ON();
    Iso15693InitReader();
    StartCountSspClk();
    uint32_t start_time = 0, eof_time = 0;

    // Password identifier Password byte
    // 0x04  Privacy
    // 0x08  Destroy SLIX-L
    // 0x10  EAS/AFI
    int res = disable_eas_15693_Slix(start_time, &eof_time, password, usepwd);



    reply_ng(CMD_HF_ISO15693_SLIX_DISABLE_EAS, res, NULL, 0);
    switch_off();
}

void EnableEAS_AFISlixIso15693(const uint8_t *password, bool usepwd) {
    LED_D_ON();
    Iso15693InitReader();
    StartCountSspClk();
    uint32_t start_time = 0, eof_time = 0;

    // Password identifier Password byte
    // 0x04  Privacy
    // 0x08  Destroy SLIX-L
    // 0x10  EAS/AFI
    int res = enable_eas_15693_Slix(start_time, &eof_time, password, usepwd);
    reply_ng(CMD_HF_ISO15693_SLIX_ENABLE_EAS, res, NULL, 0);
    switch_off();
}

void PassProtextEASSlixIso15693(const uint8_t *password) {
    LED_D_ON();
    Iso15693InitReader();
    StartCountSspClk();
    uint32_t start_time = 0, eof_time = 0;
    int res = pass_protect_EASAFI_15693_Slix(start_time, &eof_time, false, password);
    reply_ng(CMD_HF_ISO15693_SLIX_PASS_PROTECT_EAS, res, NULL, 0);
    switch_off();
}
void PassProtectAFISlixIso15693(const uint8_t *password) {
    LED_D_ON();
    Iso15693InitReader();
    StartCountSspClk();
    uint32_t start_time = 0, eof_time = 0;
    int res = pass_protect_EASAFI_15693_Slix(start_time, &eof_time, true, password);
    reply_ng(CMD_HF_ISO15693_SLIX_PASS_PROTECT_AFI, res, NULL, 0);
    switch_off();
}

void WriteAFIIso15693(const uint8_t *password, bool use_pwd, uint8_t *uid, bool use_uid, uint8_t afi) {
    LED_D_ON();
    Iso15693InitReader();
    StartCountSspClk();
    uint32_t start_time = 0, eof_time = 0;
    int res = write_afi_15693(start_time, &eof_time, password, use_pwd, uid, use_uid, afi);
    reply_ng(CMD_HF_ISO15693_WRITE_AFI, res, NULL, 0);
    switch_off();
}