simplify some code, add comments

ABS simplification from Iceman1001

armsrc/appmain.c

@@ -36,8 +36,6 @@
  #include "iso14443a.h"
 #endif
 
-#define abs(x) ( ((x)<0) ? -(x) : (x) )
-
 //=============================================================================
 // A buffer where we can queue things up to be sent through the FPGA, for
 // any purpose (fake tag, as reader, whatever). We go MSB first, since that
@@ -841,7 +839,7 @@ void ListenReaderField(int limit)
 
 		if (limit != HF_ONLY) {
 			if(mode == 1) {
-				if (abs(lf_av - lf_baseline) > REPORT_CHANGE) 
+				if (ABS(lf_av - lf_baseline) > REPORT_CHANGE) 
 					LED_D_ON();
 				else
 					LED_D_OFF();
@@ -849,7 +847,7 @@ void ListenReaderField(int limit)
 
 			lf_av_new = AvgAdc(ADC_CHAN_LF);
 			// see if there's a significant change
-			if(abs(lf_av - lf_av_new) > REPORT_CHANGE) {
+			if(ABS(lf_av - lf_av_new) > REPORT_CHANGE) {
 				Dbprintf("LF 125/134kHz Field Change: %5dmV", (MAX_ADC_LF_VOLTAGE * lf_av_new) >> 10);
 				lf_av = lf_av_new;
 				if (lf_av > lf_max)
@@ -859,7 +857,7 @@ void ListenReaderField(int limit)
 
 		if (limit != LF_ONLY) {
 			if (mode == 1){
-				if (abs(hf_av - hf_baseline) > REPORT_CHANGE) 	
+				if (ABS(hf_av - hf_baseline) > REPORT_CHANGE) 	
 					LED_B_ON();
 				else
 					LED_B_OFF();
@@ -867,7 +865,7 @@ void ListenReaderField(int limit)
 
 			hf_av_new = AvgAdc(ADC_CHAN_HF);
 			// see if there's a significant change
-			if(abs(hf_av - hf_av_new) > REPORT_CHANGE) {
+			if(ABS(hf_av - hf_av_new) > REPORT_CHANGE) {
 				Dbprintf("HF 13.56MHz Field Change: %5dmV", (MAX_ADC_HF_VOLTAGE * hf_av_new) >> 10);
 				hf_av = hf_av_new;
 				if (hf_av > hf_max)

armsrc/iso14443b.c

@@ -547,15 +547,20 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 	}
  */
 // Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by max(abs(ci),abs(cq)) + 1/2*min(abs(ci),abs(cq)))
+
+	//note: couldn't we just use MAX(ABS(ci),ABS(cq)) + (MIN(ABS(ci),ABS(cq))/2) from common.h - marshmellow
 #define CHECK_FOR_SUBCARRIER() { \
+		v = MAX(ABS(ci),ABS(cq)) + (MIN(ABS(ci),ABS(cq))/2); \
+ 	}
+		/*
 		if(ci < 0) { \
-			if(cq < 0) { /* ci < 0, cq < 0 */ \
+			if(cq < 0) { \ // ci < 0, cq < 0
 				if (cq < ci) { \
 					v = -cq - (ci >> 1); \
 				} else { \
 					v = -ci - (cq >> 1); \
 				} \
-			} else {	/* ci < 0, cq >= 0 */ \
+			} else {	\ // ci < 0, cq >= 0
 				if (cq < -ci) { \
 					v = -ci + (cq >> 1); \
 				} else { \
@@ -563,13 +568,13 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 				} \
 			} \
 		} else { \
-			if(cq < 0) { /* ci >= 0, cq < 0 */ \
+			if(cq < 0) { \ // ci >= 0, cq < 0
 				if (-cq < ci) { \
 					v = ci - (cq >> 1); \
 				} else { \
 					v = -cq + (ci >> 1); \
 				} \
-			} else {	/* ci >= 0, cq >= 0 */ \
+			} else {	\ // ci >= 0, cq >= 0
 				if (cq < ci) { \
 					v = ci + (cq >> 1); \
 				} else { \
@@ -578,6 +583,7 @@ static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
 			} \
 		} \
 	}
+		*/
 
 	switch(Demod.state) {
 		case DEMOD_UNSYNCD:

armsrc/iso15693.c

@@ -319,18 +319,7 @@ static int GetIso15693AnswerFromTag(uint8_t *receivedResponse, int maxLen, int *
 			// every other is Q. We just want power, so abs(I) + abs(Q) is
 			// close to what we want.
 			if(getNext) {
-				int8_t r;
+				int8_t r = ABS(b) + ABS(prev);
-
-				if(b < 0) {
-					r = -b;
-				} else {
-					r = b;
-				}
-				if(prev < 0) {
-					r -= prev;
-				} else {
-					r += prev;
-				}
 
 				dest[c++] = (uint8_t)r;
 
@@ -468,18 +457,7 @@ static int GetIso15693AnswerFromSniff(uint8_t *receivedResponse, int maxLen, int
 			// every other is Q. We just want power, so abs(I) + abs(Q) is
 			// close to what we want.
 			if(getNext) {
-				int8_t r;
+				int8_t r = ABS(b) + ABS(prev);
-
-				if(b < 0) {
-					r = -b;
-				} else {
-					r = b;
-				}
-				if(prev < 0) {
-					r -= prev;
-				} else {
-					r += prev;
-				}
 
 				dest[c++] = (uint8_t)r;
 
@@ -648,18 +626,7 @@ void AcquireRawAdcSamplesIso15693(void)
 			// every other is Q. We just want power, so abs(I) + abs(Q) is
 			// close to what we want.
 			if(getNext) {
-				int8_t r;
+				int8_t r = ABS(b) + ABS(prev);
-
-				if(b < 0) {
-					r = -b;
-				} else {
-					r = b;
-				}
-				if(prev < 0) {
-					r -= prev;
-				} else {
-					r += prev;
-				}
 
 				dest[c++] = (uint8_t)r;
 
@@ -713,18 +680,7 @@ void RecordRawAdcSamplesIso15693(void)
 			// every other is Q. We just want power, so abs(I) + abs(Q) is
 			// close to what we want.
 			if(getNext) {
-				int8_t r;
+				int8_t r = ABS(b) + ABS(prev);
-
-				if(b < 0) {
-					r = -b;
-				} else {
-					r = b;
-				}
-				if(prev < 0) {
-					r -= prev;
-				} else {
-					r += prev;
-				}
 
 				dest[c++] = (uint8_t)r;
 

armsrc/pcf7931.c

@@ -7,9 +7,6 @@
 #define T0_PCF 8 //period for the pcf7931 in us
 #define ALLOC 16
 
-#define abs(x) ( ((x)<0) ? -(x) : (x) )
-#define max(x,y) ( x<y ? y:x)
-
 int DemodPCF7931(uint8_t **outBlocks) {
 
     uint8_t bits[256] = {0x00};
@@ -72,7 +69,7 @@ int DemodPCF7931(uint8_t **outBlocks) {
 
 			// Switch depending on lc length:
 			// Tolerance is 1/8 of clock rate (arbitrary)
-			if (abs(lc-clock/4) < tolerance) {
+			if (ABS(lc-clock/4) < tolerance) {
 				// 16T0
 				if((i - pmc) == lc) { /* 16T0 was previous one */
 					/* It's a PMC ! */
@@ -84,7 +81,7 @@ int DemodPCF7931(uint8_t **outBlocks) {
 				else {
 					pmc = i;
 				}
-			} else if (abs(lc-clock/2) < tolerance) {
+			} else if (ABS(lc-clock/2) < tolerance) {
 				// 32TO
 				if((i - pmc) == lc) { /* 16T0 was previous one */
 					/* It's a PMC ! */
@@ -99,7 +96,7 @@ int DemodPCF7931(uint8_t **outBlocks) {
 				}
 				else
 					half_switch++;
-			} else if (abs(lc-clock) < tolerance) {
+			} else if (ABS(lc-clock) < tolerance) {
 				// 64TO
                 bits[bitidx++] = 1;
 			} else {
@@ -204,7 +201,7 @@ void ReadPCF7931() {
 						Blocks[0][ALLOC] = 1;
 						memcpy(Blocks[1], tmpBlocks[i+1], 16);
 						Blocks[1][ALLOC] = 1;
-						max_blocks = max((Blocks[1][14] & 0x7f), Blocks[1][15]) + 1;
+						max_blocks = MAX((Blocks[1][14] & 0x7f), Blocks[1][15]) + 1;
 						// Debug print
 						Dbprintf("(dbg) Max blocks: %d", max_blocks);
 						num_blocks = 2;

common/lfdemod.c

@@ -262,9 +262,9 @@ void askAmp(uint8_t *BitStream, size_t size)
 {
 	for(size_t i = 1; i<size; i++){
 		if (BitStream[i]-BitStream[i-1]>=30) //large jump up
-			BitStream[i]=127;
+			BitStream[i]=255;
 		else if(BitStream[i]-BitStream[i-1]<=-20) //large jump down
-			BitStream[i]=-127;
+			BitStream[i]=0;
 	}
 	return;
 }
@@ -464,10 +464,10 @@ int gProxII_Demod(uint8_t BitStream[], size_t *size)
 		//return start position
 		return (int) startIdx;
 	}
-	return -5;
+	return -5; //spacer bits not found - not a valid gproxII
 }
 
-//translate wave to 11111100000 (1 for each short wave 0 for each long wave)
+//translate wave to 11111100000 (1 for each short wave [higher freq] 0 for each long wave [lower freq])
 size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow)
 {
 	size_t last_transition = 0;
@@ -491,6 +491,7 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
 	// count cycles between consecutive lo-hi transitions, there should be either 8 (fc/8)
 	// or 10 (fc/10) cycles but in practice due to noise etc we may end up with anywhere
 	// between 7 to 11 cycles so fuzz it by treat anything <9 as 8 and anything else as 10
+	//  (could also be fc/5 && fc/7 for fsk1 = 4-9)
 	for(idx = 161; idx < size-20; idx++) {
 		// threshold current value
 
@@ -498,23 +499,24 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
 		else dest[idx] = 1;
 
 		// Check for 0->1 transition
-		if (dest[idx-1] < dest[idx]) { // 0 -> 1 transition
+		if (dest[idx-1] < dest[idx]) {
 			preLastSample = LastSample;
 			LastSample = currSample;
 			currSample = idx-last_transition;
 			if (currSample < (fclow-2)) {                   //0-5 = garbage noise (or 0-3)
 				//do nothing with extra garbage
-			} else if (currSample < (fchigh-1)) { //6-8 = 8 sample waves  or 3-6 = 5
+			} else if (currSample < (fchigh-1)) {           //6-8 = 8 sample waves  (or 3-6 = 5)
+				//correct previous 9 wave surrounded by 8 waves (or 6 surrounded by 5)
 				if (LastSample > (fchigh-2) && (preLastSample < (fchigh-1) || preLastSample	== 0 )){
-					dest[numBits-1]=1;  //correct previous 9 wave surrounded by 8 waves
+					dest[numBits-1]=1;
 				}
 				dest[numBits++]=1;
 
-			} else if (currSample > (fchigh) && !numBits) { //12 + and first bit = garbage 
+			} else if (currSample > (fchigh) && !numBits) { //12 + and first bit = unusable garbage 
 				//do nothing with beginning garbage
-			} else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's
+			} else if (currSample == (fclow+1) && LastSample == (fclow-1)) { // had a 7 then a 9 should be two 8's (or 4 then a 6 should be two 5's)
 				dest[numBits++]=1;
-			} else {                                         //9+ = 10 sample waves
+			} else {                                        //9+ = 10 sample waves (or 6+ = 7)
 				dest[numBits++]=0;
 			}
 			last_transition = idx;
@@ -524,6 +526,7 @@ size_t fsk_wave_demod(uint8_t * dest, size_t size, uint8_t fchigh, uint8_t fclow
 }
 
 //translate 11111100000 to 10
+//rfLen = clock, fchigh = larger field clock, fclow = smaller field clock
 size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
 		uint8_t invert, uint8_t fchigh, uint8_t fclow)
 {
@@ -533,8 +536,9 @@ size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
 	uint32_t n=1;
 	for( idx=1; idx < size; idx++) {
 		n++;
-		if (dest[idx]==lastval) continue; 
+		if (dest[idx]==lastval) continue; //skip until we hit a transition
 		
+		//find out how many bits (n) we collected
 		//if lastval was 1, we have a 1->0 crossing
 		if (dest[idx-1]==1) {
 			n = (n * fclow + rfLen/2) / rfLen;
@@ -543,6 +547,7 @@ size_t aggregate_bits(uint8_t *dest, size_t size, uint8_t rfLen,
 		}
 		if (n == 0) n = 1;
 
+		//add to our destination the bits we collected		
 		memset(dest+numBits, dest[idx-1]^invert , n);
 		numBits += n;
 		n=0;
@@ -1495,8 +1500,8 @@ int pskRawDemod(uint8_t dest[], size_t *size, int *clock, int *invert)
 	numBits += (firstFullWave / *clock);
 	//set start of wave as clock align
 	lastClkBit = firstFullWave;
-	//PrintAndLog("DEBUG: firstFullWave: %d, waveLen: %d",firstFullWave,fullWaveLen);  
+	if (g_debugMode==2) prnt("DEBUG PSK: firstFullWave: %u, waveLen: %u",firstFullWave,fullWaveLen);  
-	//PrintAndLog("DEBUG: clk: %d, lastClkBit: %d", *clock, lastClkBit);
+	if (g_debugMode==2) prnt("DEBUG: clk: %d, lastClkBit: %u, fc: %u", *clock, lastClkBit,(unsigned int) fc);
 	waveStart = 0;
 	dest[numBits++] = curPhase; //set first read bit
 	for (i = firstFullWave + fullWaveLen - 1; i < *size-3; i++){
@@ -1679,7 +1684,7 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 	i=0;
 	// warning - overwriting buffer given with raw wave data with ST removed...
 	while ( dataloc < bufsize-(clk/2) ) {
-		//compensate for long high at end of ST not being high... (we cut out the high part)
+		//compensate for long high at end of ST not being high due to signal loss... (and we cut out the start of wave high part)
 		if (buffer[dataloc]<high && buffer[dataloc]>low && buffer[dataloc+3]<high && buffer[dataloc+3]>low) {
 			for(i=0; i < clk/2-tol; ++i) {
 				buffer[dataloc+i] = high+5;
@@ -1694,7 +1699,7 @@ bool DetectST(uint8_t buffer[], size_t *size, int *foundclock) {
 			}
 		}
 		newloc += i;
-		//skip next ST
+		//skip next ST  -  we just assume it will be there from now on...
 		dataloc += clk*4;
 	}
 	*size = newloc;

include/common.h

@@ -24,6 +24,10 @@ typedef unsigned char byte_t;
 #ifndef MAX
 # define MAX(a, b) (((a) > (b)) ? (a) : (b))
 #endif
+#ifndef ABS
+# define ABS(a) ( ((a)<0) ? -(a) : (a) )
+#endif
+
 
 #define RAMFUNC __attribute((long_call, section(".ramfunc")))