Mercurial > hg > piper-vamp-js
diff base64.js @ 104:2b20e610c4c2
Fix object structure for process input in perf test
author | Chris Cannam <c.cannam@qmul.ac.uk> |
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date | Mon, 26 Sep 2016 16:18:44 +0100 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/base64.js Mon Sep 26 16:18:44 2016 +0100 @@ -0,0 +1,116 @@ +'use strict' + +if (typeof document === "undefined") { + exports.byteLength = byteLength + exports.toByteArray = toByteArray + exports.fromByteArray = fromByteArray +} + +var lookup = [] +var revLookup = [] +var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array + +var code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/' +for (var i = 0, len = code.length; i < len; ++i) { + lookup[i] = code[i] + revLookup[code.charCodeAt(i)] = i +} + +revLookup['-'.charCodeAt(0)] = 62 +revLookup['_'.charCodeAt(0)] = 63 + +function placeHoldersCount (b64) { + var len = b64.length + if (len % 4 > 0) { + throw new Error('Invalid string. Length must be a multiple of 4') + } + + // the number of equal signs (place holders) + // if there are two placeholders, than the two characters before it + // represent one byte + // if there is only one, then the three characters before it represent 2 bytes + // this is just a cheap hack to not do indexOf twice + return b64[len - 2] === '=' ? 2 : b64[len - 1] === '=' ? 1 : 0 +} + +function byteLength (b64) { + // base64 is 4/3 + up to two characters of the original data + return b64.length * 3 / 4 - placeHoldersCount(b64) +} + +function toByteArray (b64) { + var i, j, l, tmp, placeHolders, arr + var len = b64.length + placeHolders = placeHoldersCount(b64) + + arr = new Arr(len * 3 / 4 - placeHolders) + + // if there are placeholders, only get up to the last complete 4 chars + l = placeHolders > 0 ? len - 4 : len + + var L = 0 + + for (i = 0, j = 0; i < l; i += 4, j += 3) { + tmp = (revLookup[b64.charCodeAt(i)] << 18) | (revLookup[b64.charCodeAt(i + 1)] << 12) | (revLookup[b64.charCodeAt(i + 2)] << 6) | revLookup[b64.charCodeAt(i + 3)] + arr[L++] = (tmp >> 16) & 0xFF + arr[L++] = (tmp >> 8) & 0xFF + arr[L++] = tmp & 0xFF + } + + if (placeHolders === 2) { + tmp = (revLookup[b64.charCodeAt(i)] << 2) | (revLookup[b64.charCodeAt(i + 1)] >> 4) + arr[L++] = tmp & 0xFF + } else if (placeHolders === 1) { + tmp = (revLookup[b64.charCodeAt(i)] << 10) | (revLookup[b64.charCodeAt(i + 1)] << 4) | (revLookup[b64.charCodeAt(i + 2)] >> 2) + arr[L++] = (tmp >> 8) & 0xFF + arr[L++] = tmp & 0xFF + } + + return arr +} + +function tripletToBase64 (num) { + return lookup[num >> 18 & 0x3F] + lookup[num >> 12 & 0x3F] + lookup[num >> 6 & 0x3F] + lookup[num & 0x3F] +} + +function encodeChunk (uint8, start, end) { + var tmp + var output = [] + for (var i = start; i < end; i += 3) { + tmp = (uint8[i] << 16) + (uint8[i + 1] << 8) + (uint8[i + 2]) + output.push(tripletToBase64(tmp)) + } + return output.join('') +} + +function fromByteArray (uint8) { + var tmp + var len = uint8.length + var extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes + var output = '' + var parts = [] + var maxChunkLength = 16383 // must be multiple of 3 + + // go through the array every three bytes, we'll deal with trailing stuff later + for (var i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) { + parts.push(encodeChunk(uint8, i, (i + maxChunkLength) > len2 ? len2 : (i + maxChunkLength))) + } + + // pad the end with zeros, but make sure to not forget the extra bytes + if (extraBytes === 1) { + tmp = uint8[len - 1] + output += lookup[tmp >> 2] + output += lookup[(tmp << 4) & 0x3F] + output += '==' + } else if (extraBytes === 2) { + tmp = (uint8[len - 2] << 8) + (uint8[len - 1]) + output += lookup[tmp >> 10] + output += lookup[(tmp >> 4) & 0x3F] + output += lookup[(tmp << 2) & 0x3F] + output += '=' + } + + parts.push(output) + + return parts.join('') +}