101 lines
2.8 KiB
JavaScript
101 lines
2.8 KiB
JavaScript
/**
|
|
* node-compress-commons
|
|
*
|
|
* Copyright (c) 2014 Chris Talkington, contributors.
|
|
* Licensed under the MIT license.
|
|
* https://github.com/archiverjs/node-compress-commons/blob/master/LICENSE-MIT
|
|
*/
|
|
var zipUtil = require('./util');
|
|
|
|
var DATA_DESCRIPTOR_FLAG = 1 << 3;
|
|
var ENCRYPTION_FLAG = 1 << 0;
|
|
var NUMBER_OF_SHANNON_FANO_TREES_FLAG = 1 << 2;
|
|
var SLIDING_DICTIONARY_SIZE_FLAG = 1 << 1;
|
|
var STRONG_ENCRYPTION_FLAG = 1 << 6;
|
|
var UFT8_NAMES_FLAG = 1 << 11;
|
|
|
|
var GeneralPurposeBit = module.exports = function() {
|
|
if (!(this instanceof GeneralPurposeBit)) {
|
|
return new GeneralPurposeBit();
|
|
}
|
|
|
|
this.descriptor = false;
|
|
this.encryption = false;
|
|
this.utf8 = false;
|
|
this.numberOfShannonFanoTrees = 0;
|
|
this.strongEncryption = false;
|
|
this.slidingDictionarySize = 0;
|
|
|
|
return this;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.encode = function() {
|
|
return zipUtil.getShortBytes(
|
|
(this.descriptor ? DATA_DESCRIPTOR_FLAG : 0) |
|
|
(this.utf8 ? UFT8_NAMES_FLAG : 0) |
|
|
(this.encryption ? ENCRYPTION_FLAG : 0) |
|
|
(this.strongEncryption ? STRONG_ENCRYPTION_FLAG : 0)
|
|
);
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.parse = function(buf, offset) {
|
|
var flag = zipUtil.getShortBytesValue(buf, offset);
|
|
var gbp = new GeneralPurposeBit();
|
|
|
|
gbp.useDataDescriptor((flag & DATA_DESCRIPTOR_FLAG) !== 0);
|
|
gbp.useUTF8ForNames((flag & UFT8_NAMES_FLAG) !== 0);
|
|
gbp.useStrongEncryption((flag & STRONG_ENCRYPTION_FLAG) !== 0);
|
|
gbp.useEncryption((flag & ENCRYPTION_FLAG) !== 0);
|
|
gbp.setSlidingDictionarySize((flag & SLIDING_DICTIONARY_SIZE_FLAG) !== 0 ? 8192 : 4096);
|
|
gbp.setNumberOfShannonFanoTrees((flag & NUMBER_OF_SHANNON_FANO_TREES_FLAG) !== 0 ? 3 : 2);
|
|
|
|
return gbp;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.setNumberOfShannonFanoTrees = function(n) {
|
|
this.numberOfShannonFanoTrees = n;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.getNumberOfShannonFanoTrees = function() {
|
|
return this.numberOfShannonFanoTrees;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.setSlidingDictionarySize = function(n) {
|
|
this.slidingDictionarySize = n;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.getSlidingDictionarySize = function() {
|
|
return this.slidingDictionarySize;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.useDataDescriptor = function(b) {
|
|
this.descriptor = b;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.usesDataDescriptor = function() {
|
|
return this.descriptor;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.useEncryption = function(b) {
|
|
this.encryption = b;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.usesEncryption = function() {
|
|
return this.encryption;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.useStrongEncryption = function(b) {
|
|
this.strongEncryption = b;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.usesStrongEncryption = function() {
|
|
return this.strongEncryption;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.useUTF8ForNames = function(b) {
|
|
this.utf8 = b;
|
|
};
|
|
|
|
GeneralPurposeBit.prototype.usesUTF8ForNames = function() {
|
|
return this.utf8;
|
|
}; |