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comparison mupdf-source/thirdparty/zlib/examples/zran.h @ 2:b50eed0cc0ef upstream

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ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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1:1d09e1dec1d9 2:b50eed0cc0ef
1 /* zran.h -- example of deflated stream indexing and random access
2 * Copyright (C) 2005, 2012, 2018, 2023 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 * Version 1.3 18 Feb 2023 Mark Adler */
5
6 #include <stdio.h>
7 #include "zlib.h"
8
9 // Access point.
10 typedef struct point {
11 off_t out; // offset in uncompressed data
12 off_t in; // offset in compressed file of first full byte
13 int bits; // 0, or number of bits (1-7) from byte at in-1
14 unsigned char window[32768]; // preceding 32K of uncompressed data
15 } point_t;
16
17 // Access point list.
18 struct deflate_index {
19 int have; // number of access points in list
20 int mode; // -15 for raw, 15 for zlib, or 31 for gzip
21 off_t length; // total length of uncompressed data
22 point_t *list; // allocated list of access points
23 };
24
25 // Make one pass through a zlib, gzip, or raw deflate compressed stream and
26 // build an index, with access points about every span bytes of uncompressed
27 // output. gzip files with multiple members are fully indexed. span should be
28 // chosen to balance the speed of random access against the memory requirements
29 // of the list, which is about 32K bytes per access point. The return value is
30 // the number of access points on success (>= 1), Z_MEM_ERROR for out of
31 // memory, Z_BUF_ERROR for a premature end of input, Z_DATA_ERROR for a format
32 // or verification error in the input file, or Z_ERRNO for a file read error.
33 // On success, *built points to the resulting index.
34 int deflate_index_build(FILE *in, off_t span, struct deflate_index **built);
35
36 // Use the index to read len bytes from offset into buf. Return the number of
37 // bytes read or a negative error code. If data is requested past the end of
38 // the uncompressed data, then deflate_index_extract() will return a value less
39 // than len, indicating how much was actually read into buf. If given a valid
40 // index, this function should not return an error unless the file was modified
41 // somehow since the index was generated, given that deflate_index_build() had
42 // validated all of the input. If nevertheless there is a failure, Z_BUF_ERROR
43 // is returned if the compressed data ends prematurely, Z_DATA_ERROR if the
44 // deflate compressed data is not valid, Z_MEM_ERROR if out of memory,
45 // Z_STREAM_ERROR if the index is not valid, or Z_ERRNO if there is an error
46 // reading or seeking on the input file.
47 ptrdiff_t deflate_index_extract(FILE *in, struct deflate_index *index,
48 off_t offset, unsigned char *buf, size_t len);
49
50 // Deallocate an index built by deflate_index_build().
51 void deflate_index_free(struct deflate_index *index);