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246 lines
9.4 KiB
JavaScript
246 lines
9.4 KiB
JavaScript
/* zlib-adler32.js -- JavaScript implementation for the zlib crc32.
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Version: 0.2.0
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LastModified: Apr 12 2012
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Copyright (C) 2012 Masanao Izumo <iz@onicos.co.jp>
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API documentation
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==============================================================================
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Usage: crc = ZLIB.crc32(crc, buf, offset, len);
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Update a running CRC-32 with the bytes buf[offset..offset+len-1] and return the
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updated CRC-32. If buf is null, this function returns the required
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initial value for the for the crc. Pre- and post-conditioning (one's
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complement) is performed within this function so it shouldn't be done by the
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application.
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Usage example:
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var crc = ZLIB.crc32(0, null, 0, 0);
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while (read_buffer(buffer, length) != EOF) {
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crc = ZLIB.crc32(crc, buffer, 0, length);
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}
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if (crc != original_crc) error();
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==============================================================================
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Usage: crc = crc32_combine(crc1, crc2, len2);
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Combine two CRC-32 check values into one. For two sequences of bytes,
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seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
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calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
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check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
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len2.
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*/
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if( typeof ZLIB === 'undefined' ) {
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alert('ZLIB is not defined. SRC zlib.js before zlib-crc32.js')
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}
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(function() {
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/* crc32.c -- compute the CRC-32 of a data stream
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* Copyright (C) 1995-2006, 2010, 2011 Mark Adler
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* For conditions of distribution and use, see copyright notice in zlib.h
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*
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* Thanks to Rodney Brown <rbrown64@csc.com.au> for his contribution of faster
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* CRC methods: exclusive-oring 32 bits of data at a time, and pre-computing
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* tables for updating the shift register in one step with three exclusive-ors
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* instead of four steps with four exclusive-ors. This results in about a
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* factor of two increase in speed on a Power PC G4 (PPC7455) using gcc -O3.
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*/
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var crc_table = [
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0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
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0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
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0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
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0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
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0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
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0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
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0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
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0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
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0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
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0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
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0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
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0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
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0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
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0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
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0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
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0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
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0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
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0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
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0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
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0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
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0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
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0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
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0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
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0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
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0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
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0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
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0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
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0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
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0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
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0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
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0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
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0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
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0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
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0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
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0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
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0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
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0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
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0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
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0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
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0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
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0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
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0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
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0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
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0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
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0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
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0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
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0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
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0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
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0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
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0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
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0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
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0x2d02ef8d ];
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/* ========================================================================= */
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function crc32_string(crc, buf, offset, len)
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{
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if (buf == null) return 0;
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crc = crc ^ 0xffffffff;
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while (len >= 8) {
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crc = crc_table[(crc ^ buf.charCodeAt(offset++)) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf.charCodeAt(offset++)) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf.charCodeAt(offset++)) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf.charCodeAt(offset++)) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf.charCodeAt(offset++)) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf.charCodeAt(offset++)) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf.charCodeAt(offset++)) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf.charCodeAt(offset++)) & 0xff] ^ (crc >>> 8)
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len -= 8;
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}
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if (len) do {
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crc = crc_table[(crc ^ buf.charCodeAt(offset++)) & 0xff] ^ (crc >>> 8)
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} while (--len);
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return crc ^ 0xffffffff;
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}
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/* ========================================================================= */
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function crc32_array(crc, buf, offset, len)
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{
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if (buf == null) return 0;
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crc = crc ^ 0xffffffff;
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while (len >= 8) {
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crc = crc_table[(crc ^ buf[offset++]) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf[offset++]) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf[offset++]) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf[offset++]) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf[offset++]) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf[offset++]) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf[offset++]) & 0xff] ^ (crc >>> 8)
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crc = crc_table[(crc ^ buf[offset++]) & 0xff] ^ (crc >>> 8)
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len -= 8;
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}
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if (len) do {
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crc = crc_table[(crc ^ buf[offset++]) & 0xff] ^ (crc >>> 8)
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} while (--len);
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return crc ^ 0xffffffff;
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}
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/* ========================================================================= */
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ZLIB.crc32 = function(crc, buf, offset, len)
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{
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if(typeof buf === 'string') {
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return crc32_string(crc, buf, offset, len);
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} else {
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return crc32_array(crc, buf, offset, len);
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}
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};
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/* ========================================================================= */
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var GF2_DIM = 32; /* dimension of GF(2) vectors (length of CRC) */
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/* ========================================================================= */
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function gf2_matrix_times(mat, vec)
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{
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var sum;
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var mat_i = 0;
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sum = 0;
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while (vec) {
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if (vec & 1)
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sum ^= mat[mat_i];
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vec >>= 1;
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mat_i++;
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}
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return sum;
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}
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/* ========================================================================= */
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function gf2_matrix_square(square, mat)
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{
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var n;
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for (n = 0; n < GF2_DIM; n++)
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square[n] = gf2_matrix_times(mat, mat[n]);
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}
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/* ========================================================================= */
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ZLIB.crc32_combine = function(crc1, crc2, len2)
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{
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var n;
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var row;
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var even; /* even-power-of-two zeros operator */
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var odd; /* odd-power-of-two zeros operator */
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/* degenerate case (also disallow negative lengths) */
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if (len2 <= 0)
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return crc1;
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even = new Array(GF2_DIM);
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odd = new Array(GF2_DIM);
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/* put operator for one zero bit in odd */
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odd[0] = 0xedb88320; /* CRC-32 polynomial */
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row = 1;
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for (n = 1; n < GF2_DIM; n++) {
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odd[n] = row;
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row <<= 1;
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}
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/* put operator for two zero bits in even */
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gf2_matrix_square(even, odd);
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/* put operator for four zero bits in odd */
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gf2_matrix_square(odd, even);
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/* apply len2 zeros to crc1 (first square will put the operator for one
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zero byte, eight zero bits, in even) */
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do {
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/* apply zeros operator for this bit of len2 */
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gf2_matrix_square(even, odd);
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if (len2 & 1)
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crc1 = gf2_matrix_times(even, crc1);
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len2 >>= 1;
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/* if no more bits set, then done */
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if (len2 == 0)
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break;
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/* another iteration of the loop with odd and even swapped */
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gf2_matrix_square(odd, even);
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if (len2 & 1)
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crc1 = gf2_matrix_times(odd, crc1);
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len2 >>= 1;
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/* if no more bits set, then done */
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} while (len2 != 0);
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/* return combined crc */
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crc1 ^= crc2;
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return crc1;
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};
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}());
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