mirror of https://github.com/google/brotli
47 lines
1.5 KiB
C
47 lines
1.5 KiB
C
|
/* Copyright 2016 Google Inc. All Rights Reserved.
|
||
|
|
Author: vanickulin@google.com (Ivan Nikulin)
|
||
|
|
|
||
|
|
Distributed under MIT license.
|
||
|
|
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
|
||
|
|
*/
|
||
|
|
|
||
|
|
/* API for reading distances from *.dist file.
|
||
|
|
The format of *.dist file is as follows: for each backward reference there is
|
||
|
|
a position-distance pair, also a copy length may be specified. Copy length is
|
||
|
|
prefixed with flag byte 0, position-distance pair is prefixed with flag
|
||
|
|
byte 1. Each number is a 32-bit integer. Copy length always comes before
|
||
|
|
position-distance pair. Standalone copy length is allowed, in this case it is
|
||
|
|
ignored. */
|
||
|
|
|
||
|
|
#include <cassert>
|
||
|
|
#include <cstdio>
|
||
|
|
|
||
|
|
#ifndef BROTLI_RESEARCH_READ_DIST_H_
|
||
|
|
#define BROTLI_RESEARCH_READ_DIST_H_
|
||
|
|
|
||
|
|
/* Reads backwards reference from .dist file. Sets all missing fields to -1.
|
||
|
|
Returns false when EOF is met or input is corrupt. */
|
||
|
|
bool ReadBackwardReference(FILE* fin, int* copy, int* pos, int* dist) {
|
||
|
|
int c = getc(fin);
|
||
|
|
if (c == EOF) return false;
|
||
|
|
if (c == 0) {
|
||
|
|
assert(fread(copy, sizeof(int), 1, fin) == 1);
|
||
|
|
if ((c = getc(fin)) != 1) {
|
||
|
|
ungetc(c, fin);
|
||
|
|
*pos = *dist = -1;
|
||
|
|
} else {
|
||
|
|
assert(fread(pos, sizeof(int), 1, fin) == 1);
|
||
|
|
assert(fread(dist, sizeof(int), 1, fin) == 1);
|
||
|
|
}
|
||
|
|
} else if (c != 1) {
|
||
|
|
return false;
|
||
|
|
} else {
|
||
|
|
assert(fread(pos, sizeof(int), 1, fin) == 1);
|
||
|
|
assert(fread(dist, sizeof(int), 1, fin) == 1);
|
||
|
|
*copy = -1;
|
||
|
|
}
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif /* BROTLI_RESEARCH_READ_DIST_H_ */
|