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fix/update removeParity & fix securakey detection

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marshmellow42 2017-03-29 10:02:29 -04:00
commit f2ea55fb3c
2 changed files with 30 additions and 29 deletions
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29
common/lfdemod.c
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@ -35,6 +35,7 @@
#include <string.h> // for memset, memcmp and size_t
#include <stdint.h> // for uint_32+
#include <stdbool.h> // for bool
#include "parity.h" // for parity test
//**********************************************************************************************
//---------------------------------Utilities Section--------------------------------------------
@ -82,40 +83,35 @@ int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi
// 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 ans = 0;
for (uint8_t i = 0; i < bitLen; i++){
ans ^= ((bits >> i) & 1);
}
if (g_debugMode) prnt("DEBUG: ans: %d, ptype: %d, bits: %08X",ans,pType,bits);
return (ans == pType);
bool parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType) {
return oddparity32(bits) ^ pType;
}
// 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)
// takes a array of binary values, start position, length of bits per parity (includes parity bit - MAX 32),
// 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) {
uint32_t parityWd = 0;
size_t j = 0, bitCnt = 0;
size_t bitCnt = 0;
for (int word = 0; word < (bLen); word+=pLen) {
for (int bit=0; bit < pLen; bit++) {
if (word+bit >= bLen) break;
parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
BitStream[j++] = (BitStream[startIdx+word+bit]);
BitStream[bitCnt++] = (BitStream[startIdx+word+bit]);
}
if (word+pLen > bLen) break;
j--; // overwrite parity with next data
bitCnt--; // overwrite parity with next data
// if parity fails then return 0
switch (pType) {
case 3: if (BitStream[j]==1) {return 0;} break; //should be 0 spacer bit
case 2: if (BitStream[j]==0) {return 0;} break; //should be 1 spacer bit
case 3: if (BitStream[bitCnt]==1) {return 0;} break; //should be 0 spacer bit
case 2: if (BitStream[bitCnt]==0) {return 0;} break; //should be 1 spacer bit
default: if (parityTest(parityWd, pLen, pType) == 0) {return 0;} break; //test parity
}
bitCnt+=(pLen-1);
parityWd = 0;
}
// if we got here then all the parities passed
//return ID start index and size
//return size
return bitCnt;
}
@ -1687,6 +1683,7 @@ uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_
*hi = (bytebits_to_byte(BitStream, 24));
*lo = ((uint64_t)(bytebits_to_byte(BitStream + 24, 32)) << 32) | (bytebits_to_byte(BitStream + 24 + 32, 32));
} else {
if (g_debugMode) prnt("Error removing parity: %u", *size);
return 0;
}
return 1;