| // Copyright 2008 The Closure Library Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS-IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| /** |
| * @fileoverview Implementation of 32-bit hashing functions. |
| * |
| * This is a direct port from the Google Java Hash class |
| * |
| */ |
| |
| goog.provide('goog.crypt.hash32'); |
| |
| goog.require('goog.crypt'); |
| |
| |
| /** |
| * Default seed used during hashing, digits of pie. |
| * See SEED32 in http://go/base.hash.java |
| * @type {number} |
| */ |
| goog.crypt.hash32.SEED32 = 314159265; |
| |
| |
| /** |
| * Arbitrary constant used during hashing. |
| * See CONSTANT32 in http://go/base.hash.java |
| * @type {number} |
| */ |
| goog.crypt.hash32.CONSTANT32 = -1640531527; |
| |
| |
| /** |
| * Hashes a string to a 32-bit value. |
| * @param {string} str String to hash. |
| * @return {number} 32-bit hash. |
| */ |
| goog.crypt.hash32.encodeString = function(str) { |
| return goog.crypt.hash32.encodeByteArray(goog.crypt.stringToByteArray(str)); |
| }; |
| |
| |
| /** |
| * Hashes a string to a 32-bit value, converting the string to UTF-8 before |
| * doing the encoding. |
| * @param {string} str String to hash. |
| * @return {number} 32-bit hash. |
| */ |
| goog.crypt.hash32.encodeStringUtf8 = function(str) { |
| return goog.crypt.hash32.encodeByteArray( |
| goog.crypt.stringToUtf8ByteArray(str)); |
| }; |
| |
| |
| /** |
| * Hashes an integer to a 32-bit value. |
| * @param {number} value Number to hash. |
| * @return {number} 32-bit hash. |
| */ |
| goog.crypt.hash32.encodeInteger = function(value) { |
| // TODO(user): Does this make sense in JavaScript with doubles? Should we |
| // force the value to be in the correct range? |
| return goog.crypt.hash32.mix32_({ |
| a: value, |
| b: goog.crypt.hash32.CONSTANT32, |
| c: goog.crypt.hash32.SEED32 |
| }); |
| }; |
| |
| |
| /** |
| * Hashes a "byte" array to a 32-bit value using the supplied seed. |
| * @param {Array<number>} bytes Array of bytes. |
| * @param {number=} opt_offset The starting position to use for hash |
| * computation. |
| * @param {number=} opt_length Number of bytes that are used for hashing. |
| * @param {number=} opt_seed The seed. |
| * @return {number} 32-bit hash. |
| */ |
| goog.crypt.hash32.encodeByteArray = function( |
| bytes, opt_offset, opt_length, opt_seed) { |
| var offset = opt_offset || 0; |
| var length = opt_length || bytes.length; |
| var seed = opt_seed || goog.crypt.hash32.SEED32; |
| |
| var mix = { |
| a: goog.crypt.hash32.CONSTANT32, |
| b: goog.crypt.hash32.CONSTANT32, |
| c: seed |
| }; |
| |
| var keylen; |
| for (keylen = length; keylen >= 12; keylen -= 12, offset += 12) { |
| mix.a += goog.crypt.hash32.wordAt_(bytes, offset); |
| mix.b += goog.crypt.hash32.wordAt_(bytes, offset + 4); |
| mix.c += goog.crypt.hash32.wordAt_(bytes, offset + 8); |
| goog.crypt.hash32.mix32_(mix); |
| } |
| // Hash any remaining bytes |
| mix.c += length; |
| switch (keylen) { // deal with rest. Some cases fall through |
| case 11: mix.c += (bytes[offset + 10]) << 24; |
| case 10: mix.c += (bytes[offset + 9] & 0xff) << 16; |
| case 9 : mix.c += (bytes[offset + 8] & 0xff) << 8; |
| // the first byte of c is reserved for the length |
| case 8 : |
| mix.b += goog.crypt.hash32.wordAt_(bytes, offset + 4); |
| mix.a += goog.crypt.hash32.wordAt_(bytes, offset); |
| break; |
| case 7 : mix.b += (bytes[offset + 6] & 0xff) << 16; |
| case 6 : mix.b += (bytes[offset + 5] & 0xff) << 8; |
| case 5 : mix.b += (bytes[offset + 4] & 0xff); |
| case 4 : |
| mix.a += goog.crypt.hash32.wordAt_(bytes, offset); |
| break; |
| case 3 : mix.a += (bytes[offset + 2] & 0xff) << 16; |
| case 2 : mix.a += (bytes[offset + 1] & 0xff) << 8; |
| case 1 : mix.a += (bytes[offset + 0] & 0xff); |
| // case 0 : nothing left to add |
| } |
| return goog.crypt.hash32.mix32_(mix); |
| }; |
| |
| |
| /** |
| * Performs an inplace mix of an object with the integer properties (a, b, c) |
| * and returns the final value of c. |
| * @param {Object} mix Object with properties, a, b, and c. |
| * @return {number} The end c-value for the mixing. |
| * @private |
| */ |
| goog.crypt.hash32.mix32_ = function(mix) { |
| var a = mix.a, b = mix.b, c = mix.c; |
| a -= b; a -= c; a ^= c >>> 13; |
| b -= c; b -= a; b ^= a << 8; |
| c -= a; c -= b; c ^= b >>> 13; |
| a -= b; a -= c; a ^= c >>> 12; |
| b -= c; b -= a; b ^= a << 16; |
| c -= a; c -= b; c ^= b >>> 5; |
| a -= b; a -= c; a ^= c >>> 3; |
| b -= c; b -= a; b ^= a << 10; |
| c -= a; c -= b; c ^= b >>> 15; |
| mix.a = a; mix.b = b; mix.c = c; |
| return c; |
| }; |
| |
| |
| /** |
| * Returns the word at a given offset. Treating an array of bytes a word at a |
| * time is far more efficient than byte-by-byte. |
| * @param {Array<number>} bytes Array of bytes. |
| * @param {number} offset Offset in the byte array. |
| * @return {number} Integer value for the word. |
| * @private |
| */ |
| goog.crypt.hash32.wordAt_ = function(bytes, offset) { |
| var a = goog.crypt.hash32.toSigned_(bytes[offset + 0]); |
| var b = goog.crypt.hash32.toSigned_(bytes[offset + 1]); |
| var c = goog.crypt.hash32.toSigned_(bytes[offset + 2]); |
| var d = goog.crypt.hash32.toSigned_(bytes[offset + 3]); |
| return a + (b << 8) + (c << 16) + (d << 24); |
| }; |
| |
| |
| /** |
| * Converts an unsigned "byte" to signed, that is, convert a value in the range |
| * (0, 2^8-1) to (-2^7, 2^7-1) in order to be compatible with Java's byte type. |
| * @param {number} n Unsigned "byte" value. |
| * @return {number} Signed "byte" value. |
| * @private |
| */ |
| goog.crypt.hash32.toSigned_ = function(n) { |
| return n > 127 ? n - 256 : n; |
| }; |