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51 lines
1.6 KiB
C
51 lines
1.6 KiB
C
/* Copyright 2016 Google Inc. All Rights Reserved.
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Author: zip753@gmail.com (Ivan Nikulin)
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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/* API for reading distances from *.dist file.
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The format of *.dist file is as follows: for each backward reference there is
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a position-distance pair, also a copy length may be specified. Copy length is
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prefixed with flag byte 0, position-distance pair is prefixed with flag
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byte 1. Each number is a 32-bit integer. Copy length always comes before
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position-distance pair. Standalone copy length is allowed, in this case it is
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ignored. */
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#ifndef BROTLI_RESEARCH_READ_DIST_H_
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#define BROTLI_RESEARCH_READ_DIST_H_
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#include <cstdio>
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#include <cstdlib> /* exit, EXIT_FAILURE */
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#if !defined(CHECK)
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#define CHECK(X) if (!(X)) exit(EXIT_FAILURE);
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#endif
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/* Reads backwards reference from .dist file. Sets all missing fields to -1.
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Returns false when EOF is met or input is corrupt. */
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bool ReadBackwardReference(FILE* fin, int* copy, int* pos, int* dist) {
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int c = getc(fin);
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if (c == EOF) return false;
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if (c == 0) {
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CHECK(fread(copy, sizeof(int), 1, fin) == 1);
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if ((c = getc(fin)) != 1) {
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ungetc(c, fin);
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*pos = *dist = -1;
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} else {
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CHECK(fread(pos, sizeof(int), 1, fin) == 1);
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CHECK(fread(dist, sizeof(int), 1, fin) == 1);
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}
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} else if (c != 1) {
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return false;
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} else {
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CHECK(fread(pos, sizeof(int), 1, fin) == 1);
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CHECK(fread(dist, sizeof(int), 1, fin) == 1);
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*copy = -1;
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}
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return true;
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}
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#endif /* BROTLI_RESEARCH_READ_DIST_H_ */
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