add checksum to viking demod

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 5d19c89734f052e5929b257c796d045eb6e5d909..c8a2c69af82291e8486bd81cbadfb6dab1895fb7 100644 (file)
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -610,7 +610,10 @@ int VikingDemod_AM(uint8_t *dest, size_t *size) {
        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 -5;
        //return start position
        return (int) startIdx;