3 * Copyright (c) 2006 Reimar Doeffinger
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27 #include "intreadwrite.h"
30 /// Define if we may write up to 12 bytes beyond the output buffer.
31 #define OUTBUF_PADDED 1
32 /// Define if we may read up to 8 bytes beyond the input buffer.
33 #define INBUF_PADDED 1
35 typedef struct LZOContext {
36 const uint8_t *in, *in_end;
37 uint8_t *out_start, *out, *out_end;
42 * @brief Reads one byte from the input buffer, avoiding an overrun.
45 static inline int get_byte(LZOContext *c)
47 if (c->in < c->in_end)
49 c->error |= AV_LZO_INPUT_DEPLETED;
54 #define GETB(c) (*(c).in++)
56 #define GETB(c) get_byte(&(c))
60 * @brief Decodes a length value in the coding used by lzo.
61 * @param x previous byte value
62 * @param mask bits used from x
63 * @return decoded length value
65 static inline int get_len(LZOContext *c, int x, int mask)
69 while (!(x = get_byte(c))) {
70 if (cnt >= INT_MAX - 1000) {
71 c->error |= AV_LZO_ERROR;
82 * @brief Copies bytes from input to output buffer with checking.
83 * @param cnt number of bytes to copy, must be >= 0
85 static inline void copy(LZOContext *c, int cnt)
87 register const uint8_t *src = c->in;
88 register uint8_t *dst = c->out;
90 if (cnt > c->in_end - src) {
91 cnt = FFMAX(c->in_end - src, 0);
92 c->error |= AV_LZO_INPUT_DEPLETED;
94 if (cnt > c->out_end - dst) {
95 cnt = FFMAX(c->out_end - dst, 0);
96 c->error |= AV_LZO_OUTPUT_FULL;
98 #if defined(INBUF_PADDED) && defined(OUTBUF_PADDED)
105 memcpy(dst, src, cnt);
111 * @brief Copies previously decoded bytes to current position.
112 * @param back how many bytes back we start, must be > 0
113 * @param cnt number of bytes to copy, must be > 0
115 * cnt > back is valid, this will copy the bytes we just copied,
116 * thus creating a repeating pattern with a period length of back.
118 static inline void copy_backptr(LZOContext *c, int back, int cnt)
120 register uint8_t *dst = c->out;
122 if (dst - c->out_start < back) {
123 c->error |= AV_LZO_INVALID_BACKPTR;
126 if (cnt > c->out_end - dst) {
127 cnt = FFMAX(c->out_end - dst, 0);
128 c->error |= AV_LZO_OUTPUT_FULL;
130 av_memcpy_backptr(dst, back, cnt);
134 int av_lzo1x_decode(void *out, int *outlen, const void *in, int *inlen)
139 if (*outlen <= 0 || *inlen <= 0) {
142 res |= AV_LZO_OUTPUT_FULL;
144 res |= AV_LZO_INPUT_DEPLETED;
148 c.in_end = (const uint8_t *)in + *inlen;
149 c.out = c.out_start = out;
150 c.out_end = (uint8_t *)out + *outlen;
157 c.error |= AV_LZO_ERROR;
160 c.error |= AV_LZO_INPUT_DEPLETED;
166 back = (GETB(c) << 3) + ((x >> 2) & 7) + 1;
168 cnt = get_len(&c, x, 31);
170 back = (GETB(c) << 6) + (x >> 2) + 1;
172 cnt = get_len(&c, x, 7);
173 back = (1 << 14) + ((x & 8) << 11);
175 back += (GETB(c) << 6) + (x >> 2);
176 if (back == (1 << 14)) {
178 c.error |= AV_LZO_ERROR;
183 cnt = get_len(&c, x, 15);
189 back = (1 << 11) + (GETB(c) << 2) + (x >> 2) + 1;
192 back = (GETB(c) << 2) + (x >> 2) + 1;
194 copy_backptr(&c, back, cnt + 2);
200 *inlen = c.in_end - c.in;
203 *outlen = c.out_end - c.out;