41 lines
919 B
JavaScript
41 lines
919 B
JavaScript
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//
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// lz77.js
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//--------------------
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// Reads and decompresses lz77 (mode 0x10 only) files. In future may be able to recompress.
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// by RHY3756547
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//
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window.lz77 = new (function() {
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this.decompress = function(buffer) {
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var view = new DataView(buffer);
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var compType = view.getUint8(0);
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var size = view.getUint32(0, true)>>8;
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var targ = new ArrayBuffer(size);
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var targA = new Uint8Array(targ);
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var off = 4;
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var dOff = 0;
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var eof = buffer.byteLength;
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while (off<eof) {
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var flag = view.getUint8(off++);
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for (var j=7; j>=0; j--) {
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if (off>=eof) break;
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if ((flag>>j)&1) { //1=compressed, 2=raw byte
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var dat = view.getUint16(off);
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off += 2;
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var cOff = (dOff-(dat&4095))-1;
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var len = (dat>>12)+3;
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for (var k=0; k<len; k++) {
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targA[dOff++] = targA[cOff++];
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}
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} else {
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targA[dOff++] = view.getUint8(off++);
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}
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}
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}
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return targ;
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}
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})();
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