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80 lines
2.4 KiB
C
80 lines
2.4 KiB
C
/*
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Copyright 2013 Google Inc. All Rights Reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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Author: lode.vandevenne@gmail.com (Lode Vandevenne)
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Author: jyrki.alakuijala@gmail.com (Jyrki Alakuijala)
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*/
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#include "zlib_container.h"
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#include "util.h"
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#include <stdio.h>
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#include "deflate.h"
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/* Calculates the adler32 checksum of the data */
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static unsigned adler32(const unsigned char* data, size_t size)
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{
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static const unsigned sums_overflow = 5550;
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unsigned s1 = 1;
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unsigned s2 = 1 >> 16;
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while (size > 0) {
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size_t amount = size > sums_overflow ? sums_overflow : size;
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size -= amount;
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while (amount > 0) {
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s1 += (*data++);
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s2 += s1;
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amount--;
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}
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s1 %= 65521;
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s2 %= 65521;
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}
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return (s2 << 16) | s1;
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}
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void ZopfliZlibCompress(const ZopfliOptions* options,
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const unsigned char* in, size_t insize,
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unsigned char** out, size_t* outsize) {
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unsigned char bitpointer = 0;
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unsigned checksum = adler32(in, (unsigned)insize);
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unsigned cmf = 120; /* CM 8, CINFO 7. See zlib spec.*/
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unsigned flevel = 3;
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unsigned fdict = 0;
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unsigned cmfflg = 256 * cmf + fdict * 32 + flevel * 64;
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unsigned fcheck = 31 - cmfflg % 31;
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cmfflg += fcheck;
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ZOPFLI_APPEND_DATA(cmfflg / 256, out, outsize);
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ZOPFLI_APPEND_DATA(cmfflg % 256, out, outsize);
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ZopfliDeflate(options, 2 /* dynamic block */, 1 /* final */,
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in, insize, &bitpointer, out, outsize);
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ZOPFLI_APPEND_DATA((checksum >> 24) % 256, out, outsize);
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ZOPFLI_APPEND_DATA((checksum >> 16) % 256, out, outsize);
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ZOPFLI_APPEND_DATA((checksum >> 8) % 256, out, outsize);
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ZOPFLI_APPEND_DATA(checksum % 256, out, outsize);
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if (options->verbose) {
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fprintf(stderr,
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"Original Size: %d, Zlib: %d, Compression: %f%% Removed\n",
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(int)insize, (int)*outsize,
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100.0 * (double)(insize - *outsize) / (double)insize);
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}
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}
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