FFmpeg: libavutil/lzo.c Source File

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libavutil

lzo.c

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1 /*

2 * LZO 1x decompression

4 *

5 * This file is part of FFmpeg.

6 *

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.

11 *

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.

16 *

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

20 */

22 #include <string.h>

24 #include "avutil.h"

25 #include "common.h"

26 #include "intreadwrite.h"

27 #include "lzo.h"

29 /// Define if we may write up to 12 bytes beyond the output buffer.

30 #define OUTBUF_PADDED 1

31 /// Define if we may read up to 8 bytes beyond the input buffer.

32 #define INBUF_PADDED 1

34 typedef struct LZOContext {

35 const uint8_t *in, *in_end;

36 uint8_t *out_start, *out, *out_end;

37 int error;

38 } LZOContext;

40 /**

41 * @brief Reads one byte from the input buffer, avoiding an overrun.

42 * @return byte read

43 */

44 static inline int get_byte(LZOContext *c)

45 {

46 if (c->in < c->in_end)

47 return *c->in++;

48 c->error |= AV_LZO_INPUT_DEPLETED;

49 return 1;

50 }

52 #ifdef INBUF_PADDED

53 #define GETB(c) (*(c).in++)

54 #else

55 #define GETB(c) get_byte(&(c))

56 #endif

58 /**

59 * @brief Decodes a length value in the coding used by lzo.

60 * @param x previous byte value

61 * @param mask bits used from x

62 * @return decoded length value

63 */

64 static inline int get_len(LZOContext *c, int x, int mask)

65 {

66 int cnt = x & mask;

67 if (!cnt) {

68 while (!(x = get_byte(c)))

69 cnt += 255;

70 cnt += mask + x;

71 }

72 return cnt;

73 }

75 /**

76 * @brief Copies bytes from input to output buffer with checking.

77 * @param cnt number of bytes to copy, must be >= 0

78 */

79 static inline void copy(LZOContext *c, int cnt)

80 {

81 register const uint8_t *src = c->in;

82 register uint8_t *dst = c->out;

83 if (cnt > c->in_end - src) {

84 cnt = FFMAX(c->in_end - src, 0);

85 c->error |= AV_LZO_INPUT_DEPLETED;

86 }

87 if (cnt > c->out_end - dst) {

88 cnt = FFMAX(c->out_end - dst, 0);

89 c->error |= AV_LZO_OUTPUT_FULL;

90 }

91 #if defined(INBUF_PADDED) && defined(OUTBUF_PADDED)

92 AV_COPY32U(dst, src);

93 src += 4;

94 dst += 4;

95 cnt -= 4;

96 if (cnt > 0)

97 #endif

98 memcpy(dst, src, cnt);

99 c->in = src + cnt;

100 c->out = dst + cnt;

101 }

102

103 /**

104 * @brief Copies previously decoded bytes to current position.

105 * @param back how many bytes back we start, must be > 0

106 * @param cnt number of bytes to copy, must be >= 0

107 *

108 * cnt > back is valid, this will copy the bytes we just copied,

109 * thus creating a repeating pattern with a period length of back.

110 */

111 static inline void copy_backptr(LZOContext *c, int back, int cnt)

112 {

113 register uint8_t *dst = c->out;

114 if (dst - c->out_start < back) {

115 c->error |= AV_LZO_INVALID_BACKPTR;

116 return;

117 }

118 if (cnt > c->out_end - dst) {

119 cnt = FFMAX(c->out_end - dst, 0);

120 c->error |= AV_LZO_OUTPUT_FULL;

121 }

122 av_memcpy_backptr(dst, back, cnt);

123 c->out = dst + cnt;

124 }

125

126 int av_lzo1x_decode(void *out, int *outlen, const void *in, int *inlen)

127 {

128 int state = 0;

129 int x;

130 LZOContext c;

131 if (*outlen <= 0 || *inlen <= 0) {

132 int res = 0;

133 if (*outlen <= 0)

134 res |= AV_LZO_OUTPUT_FULL;

135 if (*inlen <= 0)

136 res |= AV_LZO_INPUT_DEPLETED;

137 return res;

138 }

139 c.in = in;

140 c.in_end = (const uint8_t *)in + *inlen;

141 c.out = c.out_start = out;

142 c.out_end = (uint8_t *)out + *outlen;

143 c.error = 0;

144 x = GETB(c);

145 if (x > 17) {

146 copy(&c, x - 17);

147 x = GETB(c);

148 if (x < 16)

149 c.error |= AV_LZO_ERROR;

150 }

151 if (c.in > c.in_end)

152 c.error |= AV_LZO_INPUT_DEPLETED;

153 while (!c.error) {

154 int cnt, back;

155 if (x > 15) {

156 if (x > 63) {

157 cnt = (x >> 5) - 1;

158 back = (GETB(c) << 3) + ((x >> 2) & 7) + 1;

159 } else if (x > 31) {

160 cnt = get_len(&c, x, 31);

161 x = GETB(c);

162 back = (GETB(c) << 6) + (x >> 2) + 1;

163 } else {

164 cnt = get_len(&c, x, 7);

165 back = (1 << 14) + ((x & 8) << 11);

166 x = GETB(c);

167 back += (GETB(c) << 6) + (x >> 2);

168 if (back == (1 << 14)) {

169 if (cnt != 1)

170 c.error |= AV_LZO_ERROR;

171 break;

172 }

173 }

174 } else if (!state) {

175 cnt = get_len(&c, x, 15);

176 copy(&c, cnt + 3);

177 x = GETB(c);

178 if (x > 15)

179 continue;

180 cnt = 1;

181 back = (1 << 11) + (GETB(c) << 2) + (x >> 2) + 1;

182 } else {

183 cnt = 0;

184 back = (GETB(c) << 2) + (x >> 2) + 1;

185 }

186 copy_backptr(&c, back, cnt + 2);

187 state =

188 cnt = x & 3;

189 copy(&c, cnt);

190 x = GETB(c);

191 }

192 *inlen = c.in_end - c.in;

193 if (c.in > c.in_end)

194 *inlen = 0;

195 *outlen = c.out_end - c.out;

196 return c.error;

197 }

198

199 #ifdef TEST

200 #include <stdio.h>

201 #include <lzo/lzo1x.h>

202 #include "log.h"

203 #define MAXSZ (10*1024*1024)

204

205 /* Define one of these to 1 if you wish to benchmark liblzo

206 * instead of our native implementation. */

207 #define BENCHMARK_LIBLZO_SAFE 0

208 #define BENCHMARK_LIBLZO_UNSAFE 0

209

210 int main(int argc, char *argv[]) {

211 FILE *in = fopen(argv[1], "rb");

212 uint8_t *orig = av_malloc(MAXSZ + 16);

213 uint8_t *comp = av_malloc(2*MAXSZ + 16);

214 uint8_t *decomp = av_malloc(MAXSZ + 16);

215 size_t s = fread(orig, 1, MAXSZ, in);

216 lzo_uint clen = 0;

217 long tmp[LZO1X_MEM_COMPRESS];

218 int inlen, outlen;

219 int i;

220 av_log_set_level(AV_LOG_DEBUG);

221 lzo1x_999_compress(orig, s, comp, &clen, tmp);

222 for (i = 0; i < 300; i++) {

223 START_TIMER

224 inlen = clen; outlen = MAXSZ;

225 #if BENCHMARK_LIBLZO_SAFE

226 if (lzo1x_decompress_safe(comp, inlen, decomp, &outlen, NULL))

227 #elif BENCHMARK_LIBLZO_UNSAFE

228 if (lzo1x_decompress(comp, inlen, decomp, &outlen, NULL))

229 #else

230 if (av_lzo1x_decode(decomp, &outlen, comp, &inlen))

231 #endif

232 av_log(NULL, AV_LOG_ERROR, "decompression error\n");

233 STOP_TIMER("lzod")

234 }

235 if (memcmp(orig, decomp, s))

236 av_log(NULL, AV_LOG_ERROR, "decompression incorrect\n");

237 else

238 av_log(NULL, AV_LOG_ERROR, "decompression OK\n");

239 return 0;

240 }

241 #endif

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