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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,2 +1,3 @@ | ||
| * LZ4 stream dictionary | ||
| * NodeJS streams updates | ||
| * NodeJS streams updates | ||
| * dependent blocks compression |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,76 +1,86 @@ | ||
| var Transform = require('stream').Transform | ||
| var inherits = require('util').inherits | ||
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| var encoder = require('./encoder') | ||
| var LZ4Stream = require('./encoder').LZ4Stream | ||
| var lz4_static = require('./static') | ||
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| var LZ4_compressChunk = encoder.LZ4_compressChunk | ||
| var LZ4_compressHCChunk = encoder.LZ4_compressHCChunk | ||
| var LZ4_compressBound = encoder.LZ4_compressBound | ||
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| /** | ||
| Build up chunks and encode them one by one as they are assembled | ||
| Build up blocks and encode them one by one as they are assembled | ||
| */ | ||
| function Encoder (options) { | ||
| if ( !(this instanceof Encoder) ) | ||
| return new Encoder(options) | ||
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| Transform.call(this, options) | ||
| // Options | ||
| options = options || {} | ||
| this.chunkSize = options.chunkSize || lz4_static.DEFAULT_CHUNKSIZE | ||
| this.compress = options.hc ? LZ4_compressHCChunk : LZ4_compressChunk | ||
| LZ4Stream.call(this, options) | ||
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| // Data being processed | ||
| this.buffer = [] | ||
| this.length = 0 | ||
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| this.first = true | ||
| this.chunkBound = LZ4_compressBound(this.chunkSize) + 4 | ||
| this.fast = !this.options.streamSize | ||
| } | ||
| inherits(Encoder, Transform) | ||
| Object.keys(LZ4Stream.prototype).forEach(function(method) { | ||
| if (!Encoder.prototype[method]) | ||
| Encoder.prototype[method] = LZ4Stream.prototype[method]; | ||
| }); | ||
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| Encoder.prototype._transform = function (data, encoding, done) { | ||
| // Buffer the incoming data | ||
| this.buffer.push(data) | ||
| this.length += data.length | ||
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| if (this.first) { | ||
| var buf = new Buffer(4) | ||
| buf.writeUInt32LE(lz4_static.ARCHIVE_MAGICNUMBER, 0, false) | ||
| this.push(buf) | ||
| this.first = false | ||
| } | ||
| var blockMaxSize = this.options.blockMaxSize | ||
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| if ( this.length < this.chunkSize ) return done() | ||
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| this._compressChunk(this.chunkSize, done) | ||
| } | ||
| // Not enough data for a block | ||
| if ( this.length < blockMaxSize ) return done() | ||
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| Encoder.prototype._flush = function (done) { | ||
| if (this.length === 0) return done() | ||
| // Build the data to be compressed | ||
| var buf = Buffer.concat(this.buffer, this.length) | ||
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| while ( this.length > this.chunkSize ) { | ||
| this._compressChunk(this.chunkSize) | ||
| } | ||
| // Compress the block | ||
| this.add( buf.slice(0, blockMaxSize) ) | ||
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| this._compressChunk(this.length, done) | ||
| } | ||
| // Set the remaining data | ||
| if (buf.length > blockMaxSize) { | ||
| this.buffer = [] | ||
| this.length = 0 | ||
| } else { | ||
| this.buffer = [ buf.slice(blockMaxSize) ] | ||
| this.length = buf.length - blockMaxSize | ||
| } | ||
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| Encoder.prototype._compressChunk = function (size, done) { | ||
| var buf = new Buffer(this.chunkBound) | ||
| var input = Buffer.concat(this.buffer, this.length) | ||
| var res = this.compress( input.slice(0, size), buf.slice(4) ) | ||
| if (res === 0) | ||
| return done( null, new Error('Compression error') ) | ||
| if (this.fast) { | ||
| if (this.first) { | ||
| this.push( this.header() ) | ||
| this.first = false | ||
| } | ||
| this.push( this.shiftBlock() ) | ||
| } | ||
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| buf.writeUInt32LE(res, 0, false) | ||
| this.push( buf.slice(0, res + 4) ) | ||
| done() | ||
| } | ||
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| this.length = input.length - size | ||
| this.buffer = this.length > 0 ? [ input.slice(size) ] : [] | ||
| Encoder.prototype._flush = function (done) { | ||
| if (this.length > 0) | ||
| this.add( Buffer.concat(this.buffer, this.length) ) | ||
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| if (this.fast) { | ||
| if (this.first) { | ||
| this.push( this.header() ) | ||
| this.first = false | ||
| } | ||
| var block | ||
| while ( block = this.shiftBlock() ) this.push(block) | ||
| this.push( this.tail() ) | ||
| } else { | ||
| this.push( this.done() ) | ||
| } | ||
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| if (done) done() | ||
| done() | ||
| } | ||
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| module.exports = Encoder |