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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,87 @@ | ||
| import { from } from './base.js' | ||
|
|
||
| const consonants = 'bdfghjklmnprstvz' | ||
| const vowels = 'aiou' | ||
|
|
||
| function consonantIndex (c: string): number { | ||
| const idx = consonants.indexOf(c) | ||
| if (idx === -1) { | ||
| throw new Error(`Non-proquint character: ${c}`) | ||
| } | ||
| return idx | ||
| } | ||
|
|
||
| function vowelIndex (v: string): number { | ||
| const idx = vowels.indexOf(v) | ||
| if (idx === -1) { | ||
| throw new Error(`Non-proquint character: ${v}`) | ||
| } | ||
| return idx | ||
| } | ||
|
|
||
| export const proquint = from({ | ||
| name: 'proquint', | ||
| prefix: 'p', | ||
| encode: (input: Uint8Array): string => { | ||
| // blocks of 16 bits in the pattern: | ||
| // 4 bits = consonant | ||
| // 2 bits = vowel | ||
| // 4 bits = consonant | ||
| // 2 bits = vowel | ||
| // 4 bits = consonant | ||
| // '-' | ||
| let ret = 'ro-' | ||
| for (let i = 0; i < input.length; i += 2) { | ||
| let y = input[i] << 8 | ||
| if (i + 1 !== input.length) { | ||
| y |= input[i + 1] | ||
| } | ||
| ret += consonants[y >> 12 & 0xf] | ||
| ret += vowels[(y >> 10) & 0x03] | ||
| ret += consonants[(y >> 6) & 0x0f] | ||
| if (i + 1 !== input.length) { | ||
| ret += vowels[(y >> 4) & 0x03] | ||
| ret += consonants[y & 0x0f] | ||
| } | ||
| if (i + 2 < input.length) { | ||
| ret += '-' | ||
| } | ||
| } | ||
|
|
||
| return ret | ||
| }, | ||
| decode: (input: string): Uint8Array => { | ||
| if (!input.startsWith('ro-')) { | ||
| throw new Error('Invalid proquint string') | ||
| } | ||
| input = input.slice(3) | ||
| const out = [] | ||
| let i = 0 | ||
| while (i < input.length) { | ||
| const hasFive = input.length - i >= 5 | ||
| // must have at least 3 | ||
| if (!hasFive && input.length - i < 3) { | ||
| throw new Error('Unexpected end of data') | ||
| } | ||
| let y = consonantIndex(input[i++]) << 12 | ||
| y |= vowelIndex(input[i++]) << 10 | ||
| y |= consonantIndex(input[i++]) << 6 | ||
| if (hasFive) { | ||
| y |= vowelIndex(input[i++]) << 4 | ||
| y |= consonantIndex(input[i++]) | ||
| } | ||
| out.push(y >> 8) | ||
| if (hasFive) { | ||
| out.push(y & 0xff) | ||
| if (input[i] === '-') { | ||
| if (i + 1 === input.length) { | ||
| throw new Error('Unexpected end of data') | ||
| } | ||
| i++ | ||
| } | ||
| } | ||
| } | ||
|
|
||
| return Uint8Array.from(out) | ||
| } | ||
| }) | ||
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