iota-ternary/src/trytes-to-trits/version-4.ts

Fast utility functions for conversion between trytes, trits and bytes

import { trit } from "../types"

const TRYTES_TO_TRITS = [
  0,  0,  0,
  1,  0,  0,
 -1,  1,  0,
  0,  1,  0,
  1,  1,  0,
 -1, -1,  1,
  0, -1,  1,
  1, -1,  1,
 -1,  0,  1,
  0,  0,  1,
  1,  0,  1,
 -1,  1,  1,
  0,  1,  1,
  1,  1,  1,
 -1, -1, -1,
  0, -1, -1,
  1, -1, -1,
 -1,  0, -1,
  0,  0, -1,
  1,  0, -1,
 -1,  1, -1,
  0,  1, -1,
  1,  1, -1,
 -1, -1,  0,
  0, -1,  0,
  1, -1,  0,
 -1,  0,  0
]

export function trytesToTrits(trytes: string): trit[] {
  var i, j, k, t

  const size  = trytes.length
  const trits = new Array(size * 3)

  for (i = 0, j = 0; i < size; i += 1, j += 3) {
    t = trytes[i]
    k = t === '9' ? 0 : (t.charCodeAt(0) - 64)*3

    trits[j + 0] = TRYTES_TO_TRITS[k + 0]
    trits[j + 1] = TRYTES_TO_TRITS[k + 1]
    trits[j + 2] = TRYTES_TO_TRITS[k + 2]
  }

  return trits
}