/* Table of CRCs of all 8-bit messages. */unsigned long crc_table[256];/* Flag: has the table been computed? Initially false. */int crc_table_computed = 0;/* Make the table for a fast CRC. */void make_crc_table(void){ unsigned long c; int n, k; for (n = 0; n < 256; n++) { c = (unsigned long) n; for (k = 0; k < 8; k++) { if (c & 1) c = 0xedb88320L ^ (c >> 1); else c = c >> 1; } crc_table[n] = c; } crc_table_computed = 1;}/* Update a running CRC with the bytes buf[0..len-1]-the CRCshould be initialized to all 1’s, and the transmitted valueis the 1’s complement of the final running CRC (see thecrc() routine below)). */unsigned long update_crc(unsigned long crc, unsigned char *buf, int len){ unsigned long c = crc; int n; if (!crc_table_computed) make_crc_table(); for (n = 0; n < len; n++) { c = crc_table[(c ^ buf[n]) & 0xff] ^ (c >> 8); } return c;}/* Return the CRC of the bytes buf[0..len-1]. */unsigned long crc(unsigned char *buf, int len){ return update_crc(0xffffffffL, buf, len) ^ 0xffffffffL;}
/* Round 1 */ FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */ FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */ FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */ FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */ FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */ FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */ FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */ FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */ FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */ FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */ FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */ FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */ FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */ FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */ FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */ FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */ /* Round 2 */ GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */ GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */ GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */ GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */ GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */ GG (d, a, b, c, x[10], S22, 0x2441453); /* 22 */ GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */ GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */ GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */ GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */ GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */ GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */ GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */ GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */ GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */ GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */ /* Round 3 */ HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */ HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */ HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */ HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */ HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */ HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */ HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */ HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */ HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */ HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */ HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */ HH (b, c, d, a, x[ 6], S34, 0x4881d05); /* 44 */ HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */ HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */ HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */ HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */ /* Round 4 */ II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */ II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */ II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */ II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */ II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */ II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */ II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */ II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */ II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */ II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */ II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */ II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */ II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */ II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */ II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */ II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */