crc32.js

// Based on https://github.com/brianloveswords/buffer-crc32/blob/master/index.js

var CRC_TABLE = new Int32Array([
  0x00000000,
  0x77073096,
  0xee0e612c,
  0x990951ba,
  0x076dc419,
  0x706af48f,
  0xe963a535,
  0x9e6495a3,
  0x0edb8832,
  0x79dcb8a4,
  0xe0d5e91e,
  0x97d2d988,
  0x09b64c2b,
  0x7eb17cbd,
  0xe7b82d07,
  0x90bf1d91,
  0x1db71064,
  0x6ab020f2,
  0xf3b97148,
  0x84be41de,
  0x1adad47d,
  0x6ddde4eb,
  0xf4d4b551,
  0x83d385c7,
  0x136c9856,
  0x646ba8c0,
  0xfd62f97a,
  0x8a65c9ec,
  0x14015c4f,
  0x63066cd9,
  0xfa0f3d63,
  0x8d080df5,
  0x3b6e20c8,
  0x4c69105e,
  0xd56041e4,
  0xa2677172,
  0x3c03e4d1,
  0x4b04d447,
  0xd20d85fd,
  0xa50ab56b,
  0x35b5a8fa,
  0x42b2986c,
  0xdbbbc9d6,
  0xacbcf940,
  0x32d86ce3,
  0x45df5c75,
  0xdcd60dcf,
  0xabd13d59,
  0x26d930ac,
  0x51de003a,
  0xc8d75180,
  0xbfd06116,
  0x21b4f4b5,
  0x56b3c423,
  0xcfba9599,
  0xb8bda50f,
  0x2802b89e,
  0x5f058808,
  0xc60cd9b2,
  0xb10be924,
  0x2f6f7c87,
  0x58684c11,
  0xc1611dab,
  0xb6662d3d,
  0x76dc4190,
  0x01db7106,
  0x98d220bc,
  0xefd5102a,
  0x71b18589,
  0x06b6b51f,
  0x9fbfe4a5,
  0xe8b8d433,
  0x7807c9a2,
  0x0f00f934,
  0x9609a88e,
  0xe10e9818,
  0x7f6a0dbb,
  0x086d3d2d,
  0x91646c97,
  0xe6635c01,
  0x6b6b51f4,
  0x1c6c6162,
  0x856530d8,
  0xf262004e,
  0x6c0695ed,
  0x1b01a57b,
  0x8208f4c1,
  0xf50fc457,
  0x65b0d9c6,
  0x12b7e950,
  0x8bbeb8ea,
  0xfcb9887c,
  0x62dd1ddf,
  0x15da2d49,
  0x8cd37cf3,
  0xfbd44c65,
  0x4db26158,
  0x3ab551ce,
  0xa3bc0074,
  0xd4bb30e2,
  0x4adfa541,
  0x3dd895d7,
  0xa4d1c46d,
  0xd3d6f4fb,
  0x4369e96a,
  0x346ed9fc,
  0xad678846,
  0xda60b8d0,
  0x44042d73,
  0x33031de5,
  0xaa0a4c5f,
  0xdd0d7cc9,
  0x5005713c,
  0x270241aa,
  0xbe0b1010,
  0xc90c2086,
  0x5768b525,
  0x206f85b3,
  0xb966d409,
  0xce61e49f,
  0x5edef90e,
  0x29d9c998,
  0xb0d09822,
  0xc7d7a8b4,
  0x59b33d17,
  0x2eb40d81,
  0xb7bd5c3b,
  0xc0ba6cad,
  0xedb88320,
  0x9abfb3b6,
  0x03b6e20c,
  0x74b1d29a,
  0xead54739,
  0x9dd277af,
  0x04db2615,
  0x73dc1683,
  0xe3630b12,
  0x94643b84,
  0x0d6d6a3e,
  0x7a6a5aa8,
  0xe40ecf0b,
  0x9309ff9d,
  0x0a00ae27,
  0x7d079eb1,
  0xf00f9344,
  0x8708a3d2,
  0x1e01f268,
  0x6906c2fe,
  0xf762575d,
  0x806567cb,
  0x196c3671,
  0x6e6b06e7,
  0xfed41b76,
  0x89d32be0,
  0x10da7a5a,
  0x67dd4acc,
  0xf9b9df6f,
  0x8ebeeff9,
  0x17b7be43,
  0x60b08ed5,
  0xd6d6a3e8,
  0xa1d1937e,
  0x38d8c2c4,
  0x4fdff252,
  0xd1bb67f1,
  0xa6bc5767,
  0x3fb506dd,
  0x48b2364b,
  0xd80d2bda,
  0xaf0a1b4c,
  0x36034af6,
  0x41047a60,
  0xdf60efc3,
  0xa867df55,
  0x316e8eef,
  0x4669be79,
  0xcb61b38c,
  0xbc66831a,
  0x256fd2a0,
  0x5268e236,
  0xcc0c7795,
  0xbb0b4703,
  0x220216b9,
  0x5505262f,
  0xc5ba3bbe,
  0xb2bd0b28,
  0x2bb45a92,
  0x5cb36a04,
  0xc2d7ffa7,
  0xb5d0cf31,
  0x2cd99e8b,
  0x5bdeae1d,
  0x9b64c2b0,
  0xec63f226,
  0x756aa39c,
  0x026d930a,
  0x9c0906a9,
  0xeb0e363f,
  0x72076785,
  0x05005713,
  0x95bf4a82,
  0xe2b87a14,
  0x7bb12bae,
  0x0cb61b38,
  0x92d28e9b,
  0xe5d5be0d,
  0x7cdcefb7,
  0x0bdbdf21,
  0x86d3d2d4,
  0xf1d4e242,
  0x68ddb3f8,
  0x1fda836e,
  0x81be16cd,
  0xf6b9265b,
  0x6fb077e1,
  0x18b74777,
  0x88085ae6,
  0xff0f6a70,
  0x66063bca,
  0x11010b5c,
  0x8f659eff,
  0xf862ae69,
  0x616bffd3,
  0x166ccf45,
  0xa00ae278,
  0xd70dd2ee,
  0x4e048354,
  0x3903b3c2,
  0xa7672661,
  0xd06016f7,
  0x4969474d,
  0x3e6e77db,
  0xaed16a4a,
  0xd9d65adc,
  0x40df0b66,
  0x37d83bf0,
  0xa9bcae53,
  0xdebb9ec5,
  0x47b2cf7f,
  0x30b5ffe9,
  0xbdbdf21c,
  0xcabac28a,
  0x53b39330,
  0x24b4a3a6,
  0xbad03605,
  0xcdd70693,
  0x54de5729,
  0x23d967bf,
  0xb3667a2e,
  0xc4614ab8,
  0x5d681b02,
  0x2a6f2b94,
  0xb40bbe37,
  0xc30c8ea1,
  0x5a05df1b,
  0x2d02ef8d,
])

module.exports = encoder => {
  const { buffer } = encoder
  const l = buffer.length
  let crc = -1
  for (let n = 0; n < l; n++) {
    crc = CRC_TABLE[(crc ^ buffer[n]) & 0xff] ^ (crc >>> 8)
  }
  return crc ^ -1
}