proxmark3/common/commonutil.c

//-----------------------------------------------------------------------------
// Jonathan Westhues, Sept 2005
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// Utility functions used in many places, not specific to any piece of code.
//-----------------------------------------------------------------------------
#include "commonutil.h"
#include <string.h>

/* Similar to FpgaGatherVersion this formats stored version information
 * into a string representation. It takes a pointer to the struct version_information,
 * verifies the magic properties, then stores a formatted string, prefixed by
 * prefix in dst.
 */
void FormatVersionInformation(char *dst, int len, const char *prefix, void *version_info) {
    struct version_information *v = (struct version_information *)version_info;
    dst[0] = 0;
    strncat(dst, prefix, len - 1);
    if (v->magic != VERSION_INFORMATION_MAGIC) {
        strncat(dst, "Missing/Invalid version information", len - strlen(dst) - 1);
        return;
    }
    if (v->versionversion != 1) {
        strncat(dst, "Version information not understood", len - strlen(dst) - 1);
        return;
    }
    if (!v->present) {
        strncat(dst, "Version information not available", len - strlen(dst) - 1);
        return;
    }

    strncat(dst, v->gitversion, len - strlen(dst) - 1);
    if (v->clean == 0) {
        strncat(dst, "-unclean", len - strlen(dst) - 1);
    } else if (v->clean == 2) {
        strncat(dst, "-suspect", len - strlen(dst) - 1);
    }

    strncat(dst, " ", len - strlen(dst) - 1);
    strncat(dst, v->buildtime, len - strlen(dst) - 1);
}

/*
 ref  http://www.csm.ornl.gov/~dunigan/crc.html
 Returns the value v with the bottom b [0,32] bits reflected.
 Example: reflect(0x3e23L,3) == 0x3e26
*/
uint32_t reflect(uint32_t v, int b) {
    uint32_t t = v;
    for (int i = 0; i < b; ++i) {
        if (t & 1)
            v |=  BITMASK((b - 1) - i);
        else
            v &= ~BITMASK((b - 1) - i);
        t >>= 1;
    }
    return v;
}

// https://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable

// Reverse the bits in a byte with 3 operations (64-bit multiply and modulus division):
uint8_t reflect8(uint8_t b) {
    return (b * 0x0202020202ULL & 0x010884422010ULL) % 1023;
}


// Reverse the bits in a byte with 4 operations (64-bit multiply, no division):
/*
uint8_t reflect8(uint8_t b) {
    return ((b * 0x80200802ULL) & 0x0884422110ULL) * 0x0101010101ULL >> 32;
}
*/

uint16_t reflect16(uint16_t b) {
    uint16_t v = 0;
    v |= (b & 0x8000) >> 15;
    v |= (b & 0x4000) >> 13;
    v |= (b & 0x2000) >> 11;
    v |= (b & 0x1000) >> 9;
    v |= (b & 0x0800) >> 7;
    v |= (b & 0x0400) >> 5;
    v |= (b & 0x0200) >> 3;
    v |= (b & 0x0100) >> 1;

    v |= (b & 0x0080) << 1;
    v |= (b & 0x0040) << 3;
    v |= (b & 0x0020) << 5;
    v |= (b & 0x0010) << 7;
    v |= (b & 0x0008) << 9;
    v |= (b & 0x0004) << 11;
    v |= (b & 0x0002) << 13;
    v |= (b & 0x0001) << 15;
    return v;
}

uint32_t reflect32(uint32_t b) {
    // https://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
    uint32_t v = b; // 32-bit word to reverse bit order
    // swap odd and even bits
    v = ((v >> 1) & 0x55555555) | ((v & 0x55555555) << 1);
    // swap consecutive pairs
    v = ((v >> 2) & 0x33333333) | ((v & 0x33333333) << 2);
    // swap nibbles ...
    v = ((v >> 4) & 0x0F0F0F0F) | ((v & 0x0F0F0F0F) << 4);
    // swap bytes
    v = ((v >> 8) & 0x00FF00FF) | ((v & 0x00FF00FF) << 8);
    // swap 2-byte long pairs
    v = (v >> 16) | (v               << 16);
    return v;
}

void num_to_bytes(uint64_t n, size_t len, uint8_t *dest) {
    while (len--) {
        dest[len] = (uint8_t) n;
        n >>= 8;
    }
}

uint64_t bytes_to_num(uint8_t *src, size_t len) {
    uint64_t num = 0;
    while (len--) {
        num = (num << 8) | (*src);
        src++;
    }
    return num;
}

// RotateLeft - Ultralight, Desfire
void rol(uint8_t *data, const size_t len) {
    uint8_t first = data[0];
    for (size_t i = 0; i < len - 1; i++) {
        data[i] = data[i + 1];
    }
    data[len - 1] = first;
}

void lsl(uint8_t *data, size_t len) {
    for (size_t n = 0; n < len - 1; n++) {
        data[n] = (data[n] << 1) | (data[n + 1] >> 7);
    }
    data[len - 1] <<= 1;
}


// BSWAP24 of array[3]
uint32_t le24toh(uint8_t data[3]) {
    return (data[2] << 16) | (data[1] << 8) | data[0];
}

// BSWAP24, take u32, output array
void htole24(uint32_t val, uint8_t data[3]) {
    data[0] = (uint8_t) val;
    data[1] = (uint8_t)(val >> 8);
    data[2] = (uint8_t)(val >> 16);
}


// ROL on u32
uint32_t rotl(uint32_t a, uint8_t n) {
    n &= 31;
    return (a << n) | (a >> (32 - n));
}

// ROR on u32
uint32_t rotr(uint32_t a, uint8_t n) {
    n &= 31;
    return (a >> n) | (a << (32 - n));
}