RfidResearchGroup/proxmark3
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Added a lf acquisition-mode which can do decimation and quantization, in order to be able to record longer transactions

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Martin Holst Swende 2015-01-22 23:01:29 +01:00
parent b689b842b6
commit cb366e9dbd
1 changed files with 78 additions and 0 deletions
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78
armsrc/lfops.c
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@ -8,6 +8,7 @@
// Also routines for raw mode reading/simulating of LF waveform
//-----------------------------------------------------------------------------
#include <stdlib.h>
#include "proxmark3.h"
#include "apps.h"
#include "util.h"
@ -16,6 +17,83 @@
#include "string.h"
#include "lfdemod.h"
typedef struct {
uint8_t * buffer;
uint32_t numbits;
uint8_t position;
} BitstreamOut;
/**
* @brief Pushes bit onto the stream
* @param stream
* @param bit
*/
void pushBit( BitstreamOut* stream, bool bit)
{
int bytepos = stream->position >> 3; // divide by 8
int bitpos = stream->position & 7;
*(stream->buffer+bytepos) |= (bit & 1) << (7 - bitpos);
stream->position++;
stream->numbits++;
}
void DoAcquisition(int decimation, int quantization, int trigger_threshold, bool averaging)
{
//A decimation of 2 means we keep every 2nd sample
//A decimation of 3 means we keep 1 in 3 samples.
//A quantization of 1 means one bit is discarded from the sample (division by 2).
uint8_t *dest = (uint8_t *)BigBuf;
int bufsize = BIGBUF_SIZE;
memset(dest, 0, bufsize);
// You can't decimate 8 bits more than 7 times
if(quantization > 7) quantization = 7;
// Use a bit stream to handle the output
BitstreamOut data = { dest , 0, 0};
int sample_counter = 0;
uint8_t sample = 0;
//If we want to do averaging
uint32_t sample_sum =0 ;
uint32_t sample_total_numbers =0 ;
uint32_t sample_total_saved =0 ;
for(;;) {
WDT_HIT();
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
AT91C_BASE_SSC->SSC_THR = 0x43;
LED_D_ON();
}
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
sample_total_numbers++;
if (trigger_threshold != -1 && sample < trigger_threshold)
continue;
LED_D_OFF();
trigger_threshold = -1;
sample_counter++;
sample_sum += sample;
//Check decimation
if(sample_counter < decimation) continue;
//Averaging
if(averaging) sample = sample_sum / decimation;
sample_counter = 0;
sample_sum =0;
sample_total_saved ++;
pushBit(&data, sample & 0x80);
if(quantization < 7) pushBit(&data, sample & 0x40);
if(quantization < 6) pushBit(&data, sample & 0x20);
if(quantization < 5) pushBit(&data, sample & 0x10);
if(quantization < 4) pushBit(&data, sample & 0x08);
if(quantization < 3) pushBit(&data, sample & 0x04);
if(quantization < 2) pushBit(&data, sample & 0x02);
if(quantization < 1) pushBit(&data, sample & 0x01);
if(data.numbits +1 >= bufsize) break;
}
}
Dbprintf("Done, saved %l out of %l seen samples.",sample_total_saved, sample_total_numbers);
}
/**
* Does the sample acquisition. If threshold is specified, the actual sampling