// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
-// Low frequency demod/decode commands
+// Low frequency demod/decode commands - by marshmellow, holiman, iceman and
+// many others who came before
//
// NOTES:
// LF Demod functions are placed here to allow the flexability to use client or
// There are likely many improvements to the code that could be made, please
// make suggestions...
//
+// we tried to include author comments so any questions could be directed to
+// the source.
+//
// There are 4 main sections of code below:
// Utilities Section:
// for general utilities used by multiple other functions
#include "lfdemod.h"
#include <string.h>
+//---------------------------------Utilities Section--------------------------------------------------
+
//to allow debug print calls when used not on device
void dummy(char *fmt, ...){}
-
#ifndef ON_DEVICE
#include "ui.h"
#include "cmdparser.h"
#define prnt dummy
#endif
-//---------------------------------Utilities Section--------------------------------------------------
-
-uint8_t justNoise(uint8_t *BitStream, size_t size)
-{
+uint8_t justNoise(uint8_t *BitStream, size_t size) {
static const uint8_t THRESHOLD = 123;
//test samples are not just noise
uint8_t justNoise1 = 1;
//by marshmellow
//get high and low values of a wave with passed in fuzz factor. also return noise test = 1 for passed or 0 for only noise
-int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo)
-{
+int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi, uint8_t fuzzLo) {
*high=0;
*low=255;
// get high and low thresholds
// by marshmellow
// pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
// returns 1 if passed
-uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
-{
+uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType) {
uint8_t ans = 0;
for (uint8_t i = 0; i < bitLen; i++){
ans ^= ((bits >> i) & 1);
// by marshmellow
// takes a array of binary values, start position, length of bits per parity (includes parity bit),
// Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run)
-size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
-{
+size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen) {
uint32_t parityWd = 0;
size_t j = 0, bitCnt = 0;
for (int word = 0; word < (bLen); word+=pLen) {
// takes a array of binary values, length of bits per parity (includes parity bit),
// Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
// Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
-size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
-{
+size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType) {
uint32_t parityWd = 0;
size_t j = 0, bitCnt = 0;
for (int word = 0; word < sourceLen; word+=pLen-1) {
return bitCnt;
}
-uint32_t bytebits_to_byte(uint8_t *src, size_t numbits)
-{
+uint32_t bytebits_to_byte(uint8_t *src, size_t numbits) {
uint32_t num = 0;
for(int i = 0 ; i < numbits ; i++)
{
}
//least significant bit first
-uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
-{
+uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits) {
uint32_t num = 0;
for(int i = 0 ; i < numbits ; i++)
{
return num;
}
-//by marshmellow
-//search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
-uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
-{
- return (preambleSearchEx(BitStream, preamble, pLen, size, startIdx, false)) ? 1 : 0;
-}
-
// search for given preamble in given BitStream and return success=1 or fail=0 and startIndex (where it was found) and length if not fineone
// fineone does not look for a repeating preamble for em4x05/4x69 sends preamble once, so look for it once in the first pLen bits
bool preambleSearchEx(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx, bool findone) {
return false;
}
+//by marshmellow
+//search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
+uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx) {
+ return (preambleSearchEx(BitStream, preamble, pLen, size, startIdx, false)) ? 1 : 0;
+}
+
// find start of modulating data (for fsk and psk) in case of beginning noise or slow chip startup.
size_t findModStart(uint8_t dest[], size_t size, uint8_t threshold_value, uint8_t expWaveSize) {
size_t i = 0;
//------------------------------Modulation Demods &/or Decoding Section------------------------------------------------------
+// look for Sequence Terminator - should be pulses of clk*(1 or 2), clk*2, clk*(1.5 or 2), by idx we mean graph position index...
+bool findST(int *stStopLoc, int *stStartIdx, int lowToLowWaveLen[], int highToLowWaveLen[], int clk, int tol, int buffSize, int i) {
+ for (; i < buffSize - 4; ++i) {
+ *stStartIdx += lowToLowWaveLen[i]; //caution part of this wave may be data and part may be ST.... to be accounted for in main function for now...
+ if (lowToLowWaveLen[i] >= clk*1-tol && lowToLowWaveLen[i] <= (clk*2)+tol && highToLowWaveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
+ if (lowToLowWaveLen[i+1] >= clk*2-tol && lowToLowWaveLen[i+1] <= clk*2+tol && highToLowWaveLen[i+1] > clk*3/2-tol) { //2 clocks and wave size is 1 1/2
+ if (lowToLowWaveLen[i+2] >= (clk*3)/2-tol && lowToLowWaveLen[i+2] <= clk*2+tol && highToLowWaveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
+ if (lowToLowWaveLen[i+3] >= clk*1-tol && lowToLowWaveLen[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
+ *stStopLoc = i + 3;
+ return true;
+ }
+ }
+ }
+ }
+ }
+ return false;
+}
//by marshmellow
//attempt to identify a Sequence Terminator in ASK modulated raw wave
bool DetectST_ext(uint8_t buffer[], size_t *size, int *foundclock, size_t *ststart, size_t *stend) {
int clk = 0;
int tol = 0;
int i, j, skip, start, end, low, high, minClk, waveStart;
- bool complete = false;
- int tmpbuff[bufsize / 32]; //guess rf/32 clock, if click is smaller we will only have room for a fraction of the samples captured
- int waveLen[bufsize / 32]; // if clock is larger then we waste memory in array size that is not needed...
+ //probably should malloc... || test if memory is available ... handle device side? memory danger!!! [marshmellow]
+ int tmpbuff[bufsize / 32]; // low to low wave count //guess rf/32 clock, if click is smaller we will only have room for a fraction of the samples captured
+ int waveLen[bufsize / 32]; // high to low wave count //if clock is larger then we waste memory in array size that is not needed...
size_t testsize = (bufsize < 512) ? bufsize : 512;
int phaseoff = 0;
high = low = 128;
} else tol = clk/8;
*foundclock = clk;
-
- // look for Sequence Terminator - should be pulses of clk*(1 or 1.5), clk*2, clk*(1.5 or 2)
- start = -1;
- for (i = 0; i < j - 4; ++i) {
- skip += tmpbuff[i];
- if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
- if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol && waveLen[i+1] > clk*3/2-tol) { //2 clocks and wave size is 1 1/2
- if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol && waveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
- if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
- start = i + 3;
- break;
- }
- }
- }
- }
- }
- // first ST not found - ERROR
- if (start < 0) {
+ i=0;
+ if (!findST(&start, &skip, tmpbuff, waveLen, clk, tol, j, i)) {
+ // first ST not found - ERROR
if (g_debugMode==2) prnt("DEBUG STT: first STT not found - quitting");
return false;
} else {
skip += clk*7/2; //3.5 clocks from tmpbuff[i] = end of st - also aligns for ending point
// now do it again to find the end
+ int dummy1 = 0;
end = skip;
- for (i += 3; i < j - 4; ++i) {
- end += tmpbuff[i];
- if (tmpbuff[i] >= clk*1-tol && tmpbuff[i] <= (clk*2)+tol && waveLen[i] < clk+tol) { //1 to 2 clocks depending on 2 bits prior
- if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol && waveLen[i+1] > clk*3/2-tol) { //2 clocks and wave size is 1 1/2
- if (tmpbuff[i+2] >= (clk*3)/2-tol && tmpbuff[i+2] <= clk*2+tol && waveLen[i+2] > clk-tol) { //1 1/2 to 2 clocks and at least one full clock wave
- if (tmpbuff[i+3] >= clk*1-tol && tmpbuff[i+3] <= clk*2+tol) { //1 to 2 clocks for end of ST + first bit
- complete = true;
- break;
- }
- }
- }
- }
- }
- end -= phaseoff;
- //didn't find second ST - ERROR
- if (!complete) {
+ if (!findST(&dummy1, &end, tmpbuff, waveLen, clk, tol, j, i+3)) {
+ //didn't find second ST - ERROR
if (g_debugMode==2) prnt("DEBUG STT: second STT not found - quitting");
return false;
}
+ end -= phaseoff;
if (g_debugMode==2) prnt("DEBUG STT: start of data: %d end of data: %d, datalen: %d, clk: %d, bits: %d, phaseoff: %d", skip, end, end-skip, clk, (end-skip)/clk, phaseoff);
//now begin to trim out ST so we can use normal demod cmds
start = skip;
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