X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/952a8bb59b197973e35ae187fc8acd2027ee570d..7c676e7269ce6ca6be9fbadb237873dd31b4d27d:/armsrc/lfops.c

diff --git a/armsrc/lfops.c b/armsrc/lfops.c
index f5040850..3cd2bc36 100644
--- a/armsrc/lfops.c
+++ b/armsrc/lfops.c
@@ -16,6 +16,97 @@
 #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++;
+}
+/**
+ * @brief Does LF sample acquisition, this method implements decimation and quantization in order to
+ * be able to provide longer sample traces.
+ * @param decimation - how much should the signal be decimated. A decimation of 1 means every sample, 2 means
+ * every other sample, etc.
+ * @param bits_per_sample - bits per sample. Max 8, min 1 bit per sample.
+ * @param trigger_threshold - a threshold. The sampling won't commence until this threshold has been reached. Set
+ * to -1 to ignore threshold.
+ * @param averaging If set to true, decimation will use averaging, so that if e.g. decimation is 3, the sample
+ * value that will be used is the average value of the three samples.
+ * @return the number of bits occupied by the samples.
+ */
+uint8_t DoAcquisition(int decimation, int bits_per_sample, 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);
+	if(bits_per_sample < 1) bits_per_sample = 1;
+	if(bits_per_sample > 8) bits_per_sample = 8;
+
+	// 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;
+			if (trigger_threshold != -1 && sample < trigger_threshold)
+				continue;
+			sample_total_numbers++;
+
+			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(bits_per_sample > 1)	pushBit(&data, sample & 0x40);
+			if(bits_per_sample > 2)	pushBit(&data, sample & 0x20);
+			if(bits_per_sample > 3)	pushBit(&data, sample & 0x10);
+			if(bits_per_sample > 4)	pushBit(&data, sample & 0x08);
+			if(bits_per_sample > 5)	pushBit(&data, sample & 0x04);
+			if(bits_per_sample > 6)	pushBit(&data, sample & 0x02);
+			if(bits_per_sample > 7)	pushBit(&data, sample & 0x01);
+
+			if((data.numbits >> 3) +1  >= bufsize) break;
+		}
+	}
+	Dbprintf("Done, saved %l out of %l seen samples.",sample_total_saved, sample_total_numbers);
+
+	return data.numbits;
+}
+
 
 /**
 * Does the sample acquisition. If threshold is specified, the actual sampling