X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/6b6815bccb7b11cf7847a353f8c9cf588ab0d342..af17926620a2537d165d8b00d97ce8a88d2944d2:/common/crc16.c diff --git a/common/crc16.c b/common/crc16.c index c90eeb55..21310b79 100644 --- a/common/crc16.c +++ b/common/crc16.c @@ -10,9 +10,8 @@ #define CRC16_POLY_CCITT 0x1021 #define CRC16_POLY 0x8408 -unsigned short update_crc16( unsigned short crc, unsigned char c ) -{ - unsigned short i, v, tcrc = 0; +uint16_t update_crc16( uint16_t crc, unsigned char c ) { + uint16_t i, v, tcrc = 0; v = (crc ^ c) & 0xff; for (i = 0; i < 8; i++) { @@ -28,8 +27,8 @@ uint16_t crc16(uint8_t const *message, int length, uint16_t remainder, uint16_t if (length == 0) return (~remainder); - for (int byte = 0; byte < length; ++byte) { - remainder ^= (message[byte] << 8); + for (uint32_t i = 0; i < length; ++i) { + remainder ^= (message[i] << 8); for (uint8_t bit = 8; bit > 0; --bit) { if (remainder & 0x8000) { remainder = (remainder << 1) ^ polynomial; @@ -46,18 +45,6 @@ uint16_t crc16_ccitt(uint8_t const *message, int length) { } uint16_t crc16_ccitt_kermit(uint8_t const *message, int length) { - return bit_reverse_uint16(crc16(message, length, 0x0000, CRC16_POLY_CCITT)); -} -uint16_t bit_reverse_uint16 (uint16_t value) { - const uint16_t mask0 = 0x5555; - const uint16_t mask1 = 0x3333; - const uint16_t mask2 = 0x0F0F; - const uint16_t mask3 = 0x00FF; - - value = (((~mask0) & value) >> 1) | ((mask0 & value) << 1); - value = (((~mask1) & value) >> 2) | ((mask1 & value) << 2); - value = (((~mask2) & value) >> 4) | ((mask2 & value) << 4); - value = (((~mask3) & value) >> 8) | ((mask3 & value) << 8); - - return value; + uint16_t val = crc16(message, length, 0x0000, CRC16_POLY_CCITT); + return SwapBits(val, 16); }