- // And now we loop, receiving samples.
- for(;;) {
- int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
- (DEMOD_DMA_BUFFER_SIZE-1);
- if(behindBy > maxBehindBy) {
- maxBehindBy = behindBy;
- if(behindBy > (DEMOD_DMA_BUFFER_SIZE-2)) { // TODO: understand whether we can increase/decrease as we want or not?
- Dbprintf("blew circular buffer! behindBy=0x%x", behindBy);
- goto done;
- }
- }
- if(behindBy < 2) continue;
-
- ci = upTo[0];
- cq = upTo[1];
- upTo += 2;
- lastRxCounter -= 2;
- if(upTo - dmaBuf > DEMOD_DMA_BUFFER_SIZE) {
- upTo -= DEMOD_DMA_BUFFER_SIZE;
- lastRxCounter += DEMOD_DMA_BUFFER_SIZE;
- AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
- AT91C_BASE_PDC_SSC->PDC_RNCR = DEMOD_DMA_BUFFER_SIZE;
- }
-
- samples += 2;
-
-#define HANDLE_BIT_IF_BODY \
- if(triggered) { \
- trace[traceLen++] = ((samples >> 0) & 0xff); \
- trace[traceLen++] = ((samples >> 8) & 0xff); \
- trace[traceLen++] = ((samples >> 16) & 0xff); \
- trace[traceLen++] = ((samples >> 24) & 0xff); \
- trace[traceLen++] = 0; \
- trace[traceLen++] = 0; \
- trace[traceLen++] = 0; \
- trace[traceLen++] = 0; \
- trace[traceLen++] = Uart.byteCnt; \
- memcpy(trace+traceLen, receivedCmd, Uart.byteCnt); \
- traceLen += Uart.byteCnt; \
- if(traceLen > 1000) break; \
- } \
- /* And ready to receive another command. */ \
- memset(&Uart, 0, sizeof(Uart)); \
- Uart.output = receivedCmd; \
- Uart.byteCntMax = 100; \
- Uart.state = STATE_UNSYNCD; \
- /* And also reset the demod code, which might have been */ \
- /* false-triggered by the commands from the reader. */ \
- memset(&Demod, 0, sizeof(Demod)); \
- Demod.output = receivedResponse; \
- Demod.state = DEMOD_UNSYNCD; \
-
- if(Handle14443UartBit(ci & 1)) {
- HANDLE_BIT_IF_BODY
- }
- if(Handle14443UartBit(cq & 1)) {
- HANDLE_BIT_IF_BODY
- }
-
- if(Handle14443SamplesDemod(ci, cq)) {
- // timestamp, as a count of samples
- trace[traceLen++] = ((samples >> 0) & 0xff);
- trace[traceLen++] = ((samples >> 8) & 0xff);
- trace[traceLen++] = ((samples >> 16) & 0xff);
- trace[traceLen++] = 0x80 | ((samples >> 24) & 0xff);
- // correlation metric (~signal strength estimate)
- if(Demod.metricN != 0) {
- Demod.metric /= Demod.metricN;
- }
- trace[traceLen++] = ((Demod.metric >> 0) & 0xff);
- trace[traceLen++] = ((Demod.metric >> 8) & 0xff);
- trace[traceLen++] = ((Demod.metric >> 16) & 0xff);
- trace[traceLen++] = ((Demod.metric >> 24) & 0xff);
- // length
- trace[traceLen++] = Demod.len;
- memcpy(trace+traceLen, receivedResponse, Demod.len);
- traceLen += Demod.len;
- if(traceLen > DEMOD_TRACE_SIZE) {
- DbpString("Reached trace limit");
- goto done;