244 lines
6.8 KiB
C
244 lines
6.8 KiB
C
/*
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* LZO 1x decompression
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* Copyright (c) 2006 Reimar Doeffinger
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avutil.h"
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#include "common.h"
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/// Avoid e.g. MPlayers fast_memcpy, it slows things down here.
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#undef memcpy
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#include <string.h>
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#include "lzo.h"
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/// Define if we may write up to 12 bytes beyond the output buffer.
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#define OUTBUF_PADDED 1
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/// Define if we may read up to 8 bytes beyond the input buffer.
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#define INBUF_PADDED 1
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typedef struct LZOContext {
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const uint8_t *in, *in_end;
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uint8_t *out_start, *out, *out_end;
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int error;
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} LZOContext;
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/**
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* @brief Reads one byte from the input buffer, avoiding an overrun.
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* @return byte read
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*/
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static inline int get_byte(LZOContext *c) {
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if (c->in < c->in_end)
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return *c->in++;
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c->error |= AV_LZO_INPUT_DEPLETED;
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return 1;
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}
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#ifdef INBUF_PADDED
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#define GETB(c) (*(c).in++)
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#else
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#define GETB(c) get_byte(&(c))
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#endif
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/**
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* @brief Decodes a length value in the coding used by lzo.
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* @param x previous byte value
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* @param mask bits used from x
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* @return decoded length value
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*/
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static inline int get_len(LZOContext *c, int x, int mask) {
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int cnt = x & mask;
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if (!cnt) {
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while (!(x = get_byte(c))) cnt += 255;
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cnt += mask + x;
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}
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return cnt;
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}
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//#define UNALIGNED_LOADSTORE
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#define BUILTIN_MEMCPY
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#ifdef UNALIGNED_LOADSTORE
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#define COPY2(d, s) *(uint16_t *)(d) = *(uint16_t *)(s);
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#define COPY4(d, s) *(uint32_t *)(d) = *(uint32_t *)(s);
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#elif defined(BUILTIN_MEMCPY)
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#define COPY2(d, s) memcpy(d, s, 2);
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#define COPY4(d, s) memcpy(d, s, 4);
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#else
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#define COPY2(d, s) (d)[0] = (s)[0]; (d)[1] = (s)[1];
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#define COPY4(d, s) (d)[0] = (s)[0]; (d)[1] = (s)[1]; (d)[2] = (s)[2]; (d)[3] = (s)[3];
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#endif
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/**
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* @brief Copies bytes from input to output buffer with checking.
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* @param cnt number of bytes to copy, must be >= 0
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*/
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static inline void copy(LZOContext *c, int cnt) {
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register const uint8_t *src = c->in;
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register uint8_t *dst = c->out;
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if (cnt > c->in_end - src) {
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cnt = FFMAX(c->in_end - src, 0);
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c->error |= AV_LZO_INPUT_DEPLETED;
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}
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if (cnt > c->out_end - dst) {
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cnt = FFMAX(c->out_end - dst, 0);
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c->error |= AV_LZO_OUTPUT_FULL;
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}
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#if defined(INBUF_PADDED) && defined(OUTBUF_PADDED)
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COPY4(dst, src);
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src += 4;
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dst += 4;
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cnt -= 4;
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if (cnt > 0)
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#endif
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memcpy(dst, src, cnt);
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c->in = src + cnt;
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c->out = dst + cnt;
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}
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static inline void memcpy_backptr(uint8_t *dst, int back, int cnt);
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/**
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* @brief Copies previously decoded bytes to current position.
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* @param back how many bytes back we start
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* @param cnt number of bytes to copy, must be >= 0
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*
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* cnt > back is valid, this will copy the bytes we just copied,
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* thus creating a repeating pattern with a period length of back.
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*/
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static inline void copy_backptr(LZOContext *c, int back, int cnt) {
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register const uint8_t *src = &c->out[-back];
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register uint8_t *dst = c->out;
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if (src < c->out_start || src > dst) {
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c->error |= AV_LZO_INVALID_BACKPTR;
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return;
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}
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if (cnt > c->out_end - dst) {
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cnt = FFMAX(c->out_end - dst, 0);
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c->error |= AV_LZO_OUTPUT_FULL;
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}
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memcpy_backptr(dst, back, cnt);
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c->out = dst + cnt;
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}
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static inline void memcpy_backptr(uint8_t *dst, int back, int cnt) {
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const uint8_t *src = &dst[-back];
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if (back == 1) {
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memset(dst, *src, cnt);
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} else {
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#ifdef OUTBUF_PADDED
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COPY2(dst, src);
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COPY2(dst + 2, src + 2);
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src += 4;
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dst += 4;
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cnt -= 4;
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if (cnt > 0) {
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COPY2(dst, src);
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COPY2(dst + 2, src + 2);
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COPY2(dst + 4, src + 4);
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COPY2(dst + 6, src + 6);
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src += 8;
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dst += 8;
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cnt -= 8;
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}
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#endif
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if (cnt > 0) {
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int blocklen = back;
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while (cnt > blocklen) {
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memcpy(dst, src, blocklen);
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dst += blocklen;
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cnt -= blocklen;
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blocklen <<= 1;
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}
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memcpy(dst, src, cnt);
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}
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}
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}
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void av_memcpy_backptr(uint8_t *dst, int back, int cnt) {
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memcpy_backptr(dst, back, cnt);
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}
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int av_lzo1x_decode(void *out, int *outlen, const void *in, int *inlen) {
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int state= 0;
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int x;
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LZOContext c;
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if (!*outlen || !*inlen) {
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int res = 0;
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if (!*outlen)
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res |= AV_LZO_OUTPUT_FULL;
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if (!*inlen)
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res |= AV_LZO_INPUT_DEPLETED;
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return res;
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}
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c.in = in;
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c.in_end = (const uint8_t *)in + *inlen;
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c.out = c.out_start = out;
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c.out_end = (uint8_t *)out + * outlen;
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c.error = 0;
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x = GETB(c);
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if (x > 17) {
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copy(&c, x - 17);
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x = GETB(c);
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if (x < 16) c.error |= AV_LZO_ERROR;
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}
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if (c.in > c.in_end)
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c.error |= AV_LZO_INPUT_DEPLETED;
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while (!c.error) {
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int cnt, back;
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if (x > 15) {
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if (x > 63) {
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cnt = (x >> 5) - 1;
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back = (GETB(c) << 3) + ((x >> 2) & 7) + 1;
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} else if (x > 31) {
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cnt = get_len(&c, x, 31);
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x = GETB(c);
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back = (GETB(c) << 6) + (x >> 2) + 1;
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} else {
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cnt = get_len(&c, x, 7);
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back = (1 << 14) + ((x & 8) << 11);
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x = GETB(c);
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back += (GETB(c) << 6) + (x >> 2);
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if (back == (1 << 14)) {
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if (cnt != 1)
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c.error |= AV_LZO_ERROR;
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break;
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}
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}
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} else if(!state){
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cnt = get_len(&c, x, 15);
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copy(&c, cnt + 3);
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x = GETB(c);
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if (x > 15)
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continue;
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cnt = 1;
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back = (1 << 11) + (GETB(c) << 2) + (x >> 2) + 1;
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} else {
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cnt = 0;
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back = (GETB(c) << 2) + (x >> 2) + 1;
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}
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copy_backptr(&c, back, cnt + 2);
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state=
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cnt = x & 3;
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copy(&c, cnt);
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x = GETB(c);
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}
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*inlen = c.in_end - c.in;
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if (c.in > c.in_end)
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*inlen = 0;
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*outlen = c.out_end - c.out;
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return c.error;
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}
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