-// 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 just drop it), and binary Length (length to run)
-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){
- for (int bit=0; bit < pLen; bit++){
- parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
- BitStream[j++] = (BitStream[startIdx+word+bit]);
- }
- j--;
- // if parity fails then return 0
- if (pType != 2) {
- if (parityTest(parityWd, pLen, pType) == 0) return -1;
- }
- bitCnt+=(pLen-1);
- parityWd = 0;
- }
- // if we got here then all the parities passed
- //return ID start index and size
- return bitCnt;
+// find viking preamble 0xF200 in already demoded data
+int VikingDemod_AM(uint8_t *dest, size_t *size) {
+ //make sure buffer has data
+ if (*size < 64*2) return -2;
+
+ size_t startIdx = 0;
+ uint8_t preamble[] = {1,1,1,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
+ uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
+ if (errChk == 0) return -4; //preamble not found
+ uint32_t checkCalc = bytebits_to_byte(dest+startIdx,8) ^ bytebits_to_byte(dest+startIdx+8,8) ^ bytebits_to_byte(dest+startIdx+16,8)
+ ^ bytebits_to_byte(dest+startIdx+24,8) ^ bytebits_to_byte(dest+startIdx+32,8) ^ bytebits_to_byte(dest+startIdx+40,8)
+ ^ bytebits_to_byte(dest+startIdx+48,8) ^ bytebits_to_byte(dest+startIdx+56,8);
+ if ( checkCalc != 0xA8 ) return -5;
+ if (*size != 64) return -6;
+ //return start position
+ return (int) startIdx;
+}
+
+// find presco preamble 0x10D in already demoded data
+int PrescoDemod(uint8_t *dest, size_t *size) {
+ //make sure buffer has data
+ if (*size < 64*2) return -2;
+
+ size_t startIdx = 0;
+ uint8_t preamble[] = {1,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0};
+ uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
+ if (errChk == 0) return -4; //preamble not found
+ //return start position
+ return (int) startIdx;