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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,61 @@ | ||
| import * as math from '../math.js' | ||
| import * as buffer from '../buffer.js' | ||
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|
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| export class RabinUncachedEncoder { | ||
| /** | ||
| * @param {Uint8Array} m assert(m[0] === 1) | ||
| */ | ||
| constructor (m) { | ||
| this.m = m | ||
| this.blen = m.byteLength | ||
| this.bs = new Uint8Array(this.blen) | ||
| /** | ||
| * This describes the position of the most significant byte (starts with 0 and increases with | ||
| * shift) | ||
| */ | ||
| this.bpos = 0 | ||
| } | ||
|
|
||
| /** | ||
| * Add/Xor/Substract bytes. | ||
| * | ||
| * Discards bytes that are out of range. | ||
| * @todo put this in function or inline | ||
| * | ||
| * @param {Uint8Array} cs | ||
| */ | ||
| add (cs) { | ||
| const copyLen = math.min(this.blen, cs.byteLength) | ||
| // copy from right to left until max is reached | ||
| for (let i = 0; i < copyLen; i++) { | ||
| this.bs[(this.bpos + this.blen - i - 1) % this.blen] ^= cs[cs.byteLength - i - 1] | ||
| } | ||
| } | ||
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|
||
| /** | ||
| * @param {number} byte | ||
| */ | ||
| write (byte) { | ||
| // [0,m1,m2,b] | ||
| // x <- bpos | ||
| // Shift one byte to the left, add b | ||
| this.bs[this.bpos] = byte | ||
| this.bpos = (this.bpos + 1) % this.blen | ||
| // mod | ||
| for (let i = 7; i >= 0; i--) { | ||
| if (((this.bs[this.bpos] >>> i) & 1) === 1) { | ||
| this.add(buffer.shiftNBitsLeft(this.m, i)) | ||
| } | ||
| } | ||
| // if (this.bs[this.bpos] !== 0) { error.unexpectedCase() } | ||
| // assert(this.bs[this.bpos] === 0) | ||
| } | ||
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| getFingerprint () { | ||
| const result = new Uint8Array(this.blen - 1) | ||
| for (let i = 0; i < result.byteLength; i++) { | ||
| result[i] = this.bs[(this.bpos + i + 1) % this.blen] | ||
| } | ||
| return result | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,80 @@ | ||
| import * as buffer from '../buffer.js' | ||
| import * as map from '../map.js' | ||
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|
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| export const StandardIrreducible8 = new Uint8Array([1, 189]) | ||
| export const StandardIrreducible16 = new Uint8Array([1, 244, 157]) | ||
| export const StandardIrreducible32 = new Uint8Array([1, 149, 183, 205, 191]) | ||
| export const StandardIrreducible64 = new Uint8Array([1, 133, 250, 114, 193, 250, 28, 193, 231]) | ||
| export const StandardIrreducible128 = new Uint8Array([1, 94, 109, 166, 228, 6, 222, 102, 239, 27, 128, 184, 13, 50, 112, 169, 199]) | ||
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| /** | ||
| * Maps from a modulo to the precomputed values. | ||
| * | ||
| * @type {Map<string,Uint8Array>} | ||
| */ | ||
| const _precomputedFingerprintCache = new Map() | ||
|
|
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| /** | ||
| * @param {Uint8Array} m | ||
| */ | ||
| const ensureCache = m => map.setIfUndefined(_precomputedFingerprintCache, buffer.toBase64(m), () => { | ||
| const byteLen = m.byteLength | ||
| const cache = new Uint8Array(256 * byteLen) | ||
| // Use dynamic computing to compute the cached results. | ||
| // Starting values: cache(0) = 0; cache(1) = m | ||
| cache.set(m, byteLen) | ||
| for (let bit = 1; bit < 8; bit++) { | ||
| const mBitShifted = buffer.shiftNBitsLeft(m, bit) | ||
| const bitShifted = 1 << bit | ||
| for (let j = 0; j < bitShifted; j++) { | ||
| // rest is already precomputed | ||
| const msb = bitShifted | j | ||
| const rest = msb ^ mBitShifted[0] | ||
| for (let i = 0; i < byteLen; i++) { | ||
| cache[msb * byteLen + i] = cache[rest * byteLen + i] ^ mBitShifted[i] | ||
| } | ||
| // if (cache[(bitShifted | j) * byteLen] !== (bitShifted | j)) { error.unexpectedCase() } | ||
| } | ||
| } | ||
| return cache | ||
| }) | ||
|
|
||
| export class RabinEncoder { | ||
| /** | ||
| * @param {Uint8Array} m assert(m[0] === 1) | ||
| */ | ||
| constructor (m) { | ||
| this.m = m | ||
| this.blen = m.byteLength | ||
| this.bs = new Uint8Array(this.blen) | ||
| this.cache = ensureCache(m) | ||
| /** | ||
| * This describes the position of the most significant byte (starts with 0 and increases with | ||
| * shift) | ||
| */ | ||
| this.bpos = 0 | ||
| } | ||
|
|
||
| /** | ||
| * @param {number} byte | ||
| */ | ||
| write (byte) { | ||
| // assert(this.bs[0] === 0) | ||
| // Shift one byte to the left, add b | ||
| this.bs[this.bpos] = byte | ||
| this.bpos = (this.bpos + 1) % this.blen | ||
| const msb = this.bs[this.bpos] | ||
| for (let i = 0; i < this.blen; i++) { | ||
| this.bs[(this.bpos + i) % this.blen] ^= this.cache[msb * this.blen + i] | ||
| } | ||
| // assert(this.bs[this.bpos] !== 0) | ||
| } | ||
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| getFingerprint () { | ||
| const result = new Uint8Array(this.blen - 1) | ||
| for (let i = 0; i < result.byteLength; i++) { | ||
| result[i] = this.bs[(this.bpos + i + 1) % this.blen] | ||
| } | ||
| return result | ||
| } | ||
| } |
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