static int l_iso15693_crc(lua_State *L)
{
// uint16_t Iso15693Crc(uint8_t *v, int n);
size_t size;
const char *v = luaL_checklstring(L, 1, &size);
uint16_t retval = Iso15693Crc((uint8_t *) v, size);
lua_pushinteger(L, (int) retval);
return 1;
}
// Mode 3
int CmdHF15Demod(const char *Cmd)
{
// The sampling rate is 106.353 ksps/s, for T = 18.8 us
int i, j;
int max = 0, maxPos = 0;
int skip = 4;
if (GraphTraceLen < 1000) return 0;
// First, correlate for SOF
for (i = 0; i < 100; i++) {
int corr = 0;
for (j = 0; j < arraylen(FrameSOF); j += skip) {
corr += FrameSOF[j] * GraphBuffer[i + (j / skip)];
}
if (corr > max) {
max = corr;
maxPos = i;
}
}
PrintAndLog("SOF at %d, correlation %d", maxPos,
max / (arraylen(FrameSOF) / skip));
i = maxPos + arraylen(FrameSOF) / skip;
int k = 0;
uint8_t outBuf[20];
memset(outBuf, 0, sizeof(outBuf));
uint8_t mask = 0x01;
for (;;) {
int corr0 = 0, corr1 = 0, corrEOF = 0;
for (j = 0; j < arraylen(Logic0); j += skip) {
corr0 += Logic0[j] * GraphBuffer[i + (j / skip)];
}
for (j = 0; j < arraylen(Logic1); j += skip) {
corr1 += Logic1[j] * GraphBuffer[i + (j / skip)];
}
for (j = 0; j < arraylen(FrameEOF); j += skip) {
corrEOF += FrameEOF[j] * GraphBuffer[i + (j / skip)];
}
// Even things out by the length of the target waveform.
corr0 *= 4;
corr1 *= 4;
if (corrEOF > corr1 && corrEOF > corr0) {
PrintAndLog("EOF at %d", i);
break;
} else if (corr1 > corr0) {
i += arraylen(Logic1) / skip;
outBuf[k] |= mask;
} else {
i += arraylen(Logic0) / skip;
}
mask <<= 1;
if (mask == 0) {
k++;
mask = 0x01;
}
if ((i + (int)arraylen(FrameEOF)) >= GraphTraceLen) {
PrintAndLog("ran off end!");
break;
}
}
if (mask != 0x01) {
PrintAndLog("error, uneven octet! (discard extra bits!)");
PrintAndLog(" mask=%02x", mask);
}
PrintAndLog("%d octets", k);
for (i = 0; i < k; i++) {
PrintAndLog("# %2d: %02x ", i, outBuf[i]);
}
PrintAndLog("CRC=%04x", Iso15693Crc(outBuf, k - 2));
return 0;
}
