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