aaac7fed
 liuqimichale
add
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'use strict'
var Buffer = require('safe-buffer').Buffer
var Transform = require('stream').Transform
var inherits = require('inherits')
function throwIfNotStringOrBuffer (val, prefix) {
if (!Buffer.isBuffer(val) && typeof val !== 'string') {
throw new TypeError(prefix + ' must be a string or a buffer')
}
}
function HashBase (blockSize) {
Transform.call(this)
this._block = Buffer.allocUnsafe(blockSize)
this._blockSize = blockSize
this._blockOffset = 0
this._length = [0, 0, 0, 0]
this._finalized = false
}
inherits(HashBase, Transform)
HashBase.prototype._transform = function (chunk, encoding, callback) {
var error = null
try {
this.update(chunk, encoding)
} catch (err) {
error = err
}
callback(error)
}
HashBase.prototype._flush = function (callback) {
var error = null
try {
this.push(this.digest())
} catch (err) {
error = err
}
callback(error)
}
HashBase.prototype.update = function (data, encoding) {
throwIfNotStringOrBuffer(data, 'Data')
if (this._finalized) throw new Error('Digest already called')
if (!Buffer.isBuffer(data)) data = Buffer.from(data, encoding)
// consume data
var block = this._block
var offset = 0
while (this._blockOffset + data.length - offset >= this._blockSize) {
for (var i = this._blockOffset; i < this._blockSize;) block[i++] = data[offset++]
this._update()
this._blockOffset = 0
}
while (offset < data.length) block[this._blockOffset++] = data[offset++]
// update length
for (var j = 0, carry = data.length * 8; carry > 0; ++j) {
this._length[j] += carry
carry = (this._length[j] / 0x0100000000) | 0
if (carry > 0) this._length[j] -= 0x0100000000 * carry
}
return this
}
HashBase.prototype._update = function () {
throw new Error('_update is not implemented')
}
HashBase.prototype.digest = function (encoding) {
if (this._finalized) throw new Error('Digest already called')
this._finalized = true
var digest = this._digest()
if (encoding !== undefined) digest = digest.toString(encoding)
// reset state
this._block.fill(0)
this._blockOffset = 0
for (var i = 0; i < 4; ++i) this._length[i] = 0
return digest
}
HashBase.prototype._digest = function () {
throw new Error('_digest is not implemented')
}
module.exports = HashBase
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