GRASS GIS 8 Programmer's Manual 8.4.1(2025)-45ca3179ab
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cmprlz4.c
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1/*
2 ****************************************************************************
3 * -- GRASS Development Team --
4 *
5 * MODULE: GRASS gis library
6 * FILENAME: cmprlz4.c
7 * AUTHOR(S): Eric G. Miller <egm2@jps.net>
8 * Markus Metz
9 * PURPOSE: To provide an interface to lz4 for compressing and
10 * decompressing data using LZ4. It's primary use is in
11 * the storage and reading of GRASS floating point rasters.
12 *
13 * ALGORITHM: https://code.google.com/p/lz4/
14 * DATE CREATED: Dec 18 2015
15 * COPYRIGHT: (C) 2015 by the GRASS Development Team
16 *
17 * This program is free software under the GNU General Public
18 * License (version 2 or greater). Read the file COPYING that
19 * comes with GRASS for details.
20 *
21 *****************************************************************************/
22
23/********************************************************************
24 * int *
25 * G_lz4_compress (src, srz_sz, dst, dst_sz) *
26 * int src_sz, dst_sz; *
27 * unsigned char *src, *dst; *
28 * ---------------------------------------------------------------- *
29 * This function is a wrapper around the LZ4 compression function. *
30 * It uses an all or nothing call. *
31 * If you need a continuous compression scheme, you'll have to code *
32 * your own. *
33 * In order to do a single pass compression, the input src must be *
34 * copied to a buffer larger than the data. This may cause *
35 * performance degradation. *
36 * *
37 * The function either returns the number of bytes of compressed *
38 * data in dst, or an error code. *
39 * *
40 * Errors include: *
41 * -1 -- Compression failed. *
42 * -2 -- dst is too small. *
43 * *
44 * ================================================================ *
45 * int *
46 * G_lz4_expand (src, src_sz, dst, dst_sz) *
47 * int src_sz, dst_sz; *
48 * unsigned char *src, *dst; *
49 * ---------------------------------------------------------------- *
50 * This function is a wrapper around the lz4 decompression *
51 * function. It uses a single pass call. If you need a continuous *
52 * expansion scheme, you'll have to code your own. *
53 * *
54 * The function returns the number of bytes expanded into 'dst' or *
55 * and error code. *
56 * *
57 * Errors include: *
58 * -1 -- Expansion failed. *
59 * *
60 ********************************************************************
61 */
62
63#include <grass/config.h>
64
65#include <grass/gis.h>
66#include <grass/glocale.h>
67
68#include "lz4.h"
69
70int G_lz4_compress_bound(int src_sz)
71{
72 /* LZ4 has a fast version if destLen is large enough
73 * to hold a worst case result
74 */
75 return LZ4_compressBound(src_sz);
76}
77
78int G_lz4_compress(unsigned char *src, int src_sz, unsigned char *dst,
79 int dst_sz)
80{
81 int err, nbytes, buf_sz;
82 unsigned char *buf;
83
84 /* Catch errors early */
85 if (src == NULL || dst == NULL) {
86 if (src == NULL)
87 G_warning(_("No source buffer"));
88
89 if (dst == NULL)
90 G_warning(_("No destination buffer"));
91 return -1;
92 }
93
94 /* Don't do anything if either of these are true */
95 if (src_sz <= 0 || dst_sz <= 0) {
96 if (src_sz <= 0)
97 G_warning(_("Invalid source buffer size %d"), src_sz);
98 if (dst_sz <= 0)
99 G_warning(_("Invalid destination buffer size %d"), dst_sz);
100 return 0;
101 }
102
103 /* Output buffer should be large enough for single pass compression */
104 buf = dst;
105 buf_sz = G_lz4_compress_bound(src_sz);
106 if (buf_sz > dst_sz) {
107 G_warning(
108 "G_lz4_compress(): programmer error, destination is too small");
109 if (NULL ==
110 (buf = (unsigned char *)G_calloc(buf_sz, sizeof(unsigned char))))
111 return -1;
112 }
113 else
114 buf_sz = dst_sz;
115
116 /* Do single pass compression */
117 err = LZ4_compress_default((char *)src, (char *)buf, src_sz, buf_sz);
118
119 if (err <= 0) {
120 G_warning(_("LZ4 compression error"));
121 if (buf != dst)
122 G_free(buf);
123 return -1;
124 }
125 if (err >= src_sz) {
126 /* compression not possible */
127 if (buf != dst)
128 G_free(buf);
129 return -2;
130 }
131
132 /* bytes of compressed data is return value */
133 nbytes = err;
134
135 if (buf != dst) {
136 /* Copy the data from buf to dst */
137 for (err = 0; err < nbytes; err++)
138 dst[err] = buf[err];
139
140 G_free(buf);
141 }
142
143 return nbytes;
144}
145
146int G_lz4_expand(unsigned char *src, int src_sz, unsigned char *dst, int dst_sz)
147{
148 int err, nbytes;
149
150 /* Catch error condition */
151 if (src == NULL || dst == NULL) {
152 if (src == NULL)
153 G_warning(_("No source buffer"));
154
155 if (dst == NULL)
156 G_warning(_("No destination buffer"));
157 return -2;
158 }
159
160 /* Don't do anything if either of these are true */
161 if (src_sz <= 0 || dst_sz <= 0) {
162 if (src_sz <= 0)
163 G_warning(_("Invalid source buffer size %d"), src_sz);
164 if (dst_sz <= 0)
165 G_warning(_("Invalid destination buffer size %d"), dst_sz);
166 return 0;
167 }
168
169 /* Do single pass decompress */
170 err = LZ4_decompress_safe((char *)src, (char *)dst, src_sz, dst_sz);
171 /* err = LZ4_decompress_fast(src, dst, src_sz); */
172
173 if (err <= 0) {
174 G_warning(_("LZ4 decompression error"));
175 return -1;
176 }
177
178 /* Number of bytes inflated to output stream is return value */
179 nbytes = err;
180
181 if (nbytes != dst_sz) {
182 /* TODO: it is not an error if destination is larger than needed */
183 G_warning(_("Got uncompressed size %d, expected %d"), (int)nbytes,
184 dst_sz);
185 return -1;
186 }
187
188 return nbytes;
189}
190
191/* vim: set softtabstop=4 shiftwidth=4 expandtab: */
void G_free(void *buf)
Free allocated memory.
Definition alloc.c:150
#define NULL
Definition ccmath.h:32
int G_lz4_compress(unsigned char *src, int src_sz, unsigned char *dst, int dst_sz)
Definition cmprlz4.c:78
int G_lz4_expand(unsigned char *src, int src_sz, unsigned char *dst, int dst_sz)
Definition cmprlz4.c:146
int G_lz4_compress_bound(int src_sz)
Definition cmprlz4.c:70
void G_warning(const char *msg,...)
Print a warning message to stderr.
Definition gis/error.c:203
int LZ4_compressBound(int isize)
Definition lz4.c:638
int LZ4_compress_default(const char *source, char *dest, int inputSize, int maxOutputSize)
Definition lz4.c:1448
LZ4_FORCE_O2_GCC_PPC64LE int LZ4_decompress_safe(const char *source, char *dest, int compressedSize, int maxDecompressedSize)
Definition lz4.c:2093
SYMBOL * err(FILE *fp, SYMBOL *s, char *msg)