Sakurai/pdf.js
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avoid frequent calls to ensureBuffer during decompression

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This commit is contained in:
Andreas Gal 2011-06-22 01:12:27 -04:00
parent d64691a95b
commit 7bac97e0fb
1 changed files with 28 additions and 20 deletions
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48
pdf.js
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@ -61,7 +61,7 @@ var Stream = (function() {
this.bytes = Uint8Array(arrayBuffer);
this.start = start || 0;
this.pos = this.start;
this.end = (start + length) || this.bytes.byteLength;
this.end = (start + length) || this.bytes.length;
this.dict = dict;
}
@ -516,33 +516,41 @@ var FlateStream = (function() {
error("Unknown block type in flate stream");
}
var buffer = this.buffer;
var limit = buffer ? buffer.length : 0;
var pos = this.bufferLength;
while (true) {
var code1 = this.getCode(litCodeTable);
if (code1 < 256) {
if (pos + 1 >= limit) {
buffer = this.ensureBuffer(pos + 1);
limit = buffer.length;
}
buffer[pos++] = code1;
continue;
}
if (code1 == 256) {
this.bufferLength = pos;
return;
}
if (code1 < 256) {
var buffer = this.ensureBuffer(pos + 1);
buffer[pos++] = code1;
} else {
code1 -= 257;
code1 = lengthDecode[code1];
var code2 = code1 >> 16;
if (code2 > 0)
code2 = this.getBits(code2);
var len = (code1 & 0xffff) + code2;
code1 = this.getCode(distCodeTable);
code1 = distDecode[code1];
code2 = code1 >> 16;
if (code2 > 0)
code2 = this.getBits(code2);
var dist = (code1 & 0xffff) + code2;
var buffer = this.ensureBuffer(pos + len);
for (var k = 0; k < len; ++k, ++pos)
buffer[pos] = buffer[pos - dist];
code1 -= 257;
code1 = lengthDecode[code1];
var code2 = code1 >> 16;
if (code2 > 0)
code2 = this.getBits(code2);
var len = (code1 & 0xffff) + code2;
code1 = this.getCode(distCodeTable);
code1 = distDecode[code1];
code2 = code1 >> 16;
if (code2 > 0)
code2 = this.getBits(code2);
var dist = (code1 & 0xffff) + code2;
if (pos + len >= limit) {
buffer = this.ensureBuffer(pos + len);
limit = buffer.length;
}
for (var k = 0; k < len; ++k, ++pos)
buffer[pos] = buffer[pos - dist];
}
};