A Go implementation of Pearson hashing

pearson.go

package pearson

/* Get an initial hash value by passing in the length of the array. */
func Init(length int) (hash byte) { return byte(length % 256) }

/* Given the hash of a string S0..SN and the character SN+1,
   get the hash of the string S0..SN+1.
*/
func FeedByte(oldhash byte, next byte) (newhash byte) {
  /* The following table is the result of the pseudorandom order at
     http://burtleburtle.net/bob/hash/pearson.html implemented as follows:

      x := make([]byte, 256);
        for i := 0; i < 256; i++ {
          x[i] = byte(i)
          }
        k := 7
        for j := 0; j < 4; j++ {
          for i := 0; i < 256; i++ {
            s := x[i]
            k  = (k+int(s)) % 256
            x[i] = x[k]
            x[k] = s
            }
          }
  */
  return []byte{  49, 118,  63, 252,  13, 155, 114, 130, 137,  40, 210,  62, 219, 246, 136, 221,
                 174, 106,  37, 227, 166,  25, 139,  19, 204, 212,  64, 176,  70,  11, 170,  58,
                 146,  24, 123,  77, 184, 248, 108, 251,  43, 171,  12, 141, 126,  41,  95, 142,
                 167,  46, 178, 235,  30,  75,  45, 208, 110, 230, 226,  50,  32, 112, 156, 180,
                 205,  68, 202, 203,  82,   7, 247, 217, 223,  71, 116,  76,   6,  31, 194, 183,
                  15, 102,  97, 215, 234, 240,  53, 119,  52,  47, 179,  99, 199,   8, 101,  35,
                  65, 132, 154, 239, 148,  51, 216,  74,  93, 192,  42,  86, 165, 113,  89,  48,
                 100, 195,  29, 211, 169,  38,  57, 214, 127, 117,  59,  39, 209,  88,   1, 134,
                  92, 163,   0,  66, 237,  22, 164, 200,  85,   9, 190, 129, 111, 172, 231,  14,
                 181, 206, 128,  23, 187,  73, 149, 193, 241, 236, 197, 159,  55, 125, 196,  60,
                 161, 238, 245,  94,  87, 157, 122, 158, 115, 207,  17,  20, 145, 232, 107,  16,
                  21, 185,  33, 225, 175, 253,  81, 182,  67, 243,  69, 220, 153,   5, 143,   3,
                  26, 213, 147, 222, 105, 188, 229, 191,  72, 177, 250, 135, 152, 121, 218,  44,
                 120, 140, 138,  28,  84, 186, 198, 131,  54,   2,  56,  78, 173, 151,  83,  27,
                 255, 144, 249, 189, 104,   4, 168,  98, 162, 150, 254, 242, 109,  34, 133, 224,
                 228,  79, 103, 201, 160,  90,  18,  61,  10, 233,  91,  80, 124,  96, 244,  36 }[ byte(int(oldhash + next) % 256) ]
  }

// Get the hash of a []byte.
func Hash(msg []byte) byte {
  hash := Init(len(msg))
  for _, v := range msg { hash = FeedByte(hash, v) }
  return hash
  }

// Get the hash a string.
// This just interprets the string as a []byte,
// using Hash().
func HashString(msg string) byte { return Hash([]byte(msg)) }