mirror of
https://github.com/FFmpeg/FFmpeg.git
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269 lines
7.6 KiB
C
269 lines
7.6 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 FFmpeg.
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*
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* FFmpeg 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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* FFmpeg 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 FFmpeg; 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 "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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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 read one byte from input buffer, avoiding 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 |= 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 decode 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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/**
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* \brief copy 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 uint8_t *src = c->in;
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register uint8_t *dst = c->out;
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if (src + cnt > c->in_end || src + cnt < src) {
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cnt = c->in_end - src;
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c->error |= LZO_INPUT_DEPLETED;
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}
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if (dst + cnt > c->out_end || dst + cnt < dst) {
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cnt = c->out_end - dst;
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c->error |= LZO_OUTPUT_FULL;
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}
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#if defined(INBUF_PADDED) && defined(OUTBUF_PADDED)
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dst[0] = src[0];
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dst[1] = src[1];
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dst[2] = src[2];
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dst[3] = src[3];
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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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/**
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* \brief copy 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 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 |= LZO_INVALID_BACKPTR;
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return;
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}
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if (dst + cnt > c->out_end || dst + cnt < dst) {
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cnt = c->out_end - dst;
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c->error |= LZO_OUTPUT_FULL;
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}
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if (back == 1) {
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memset(dst, *src, cnt);
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dst += cnt;
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} else {
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#ifdef OUTBUF_PADDED
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dst[0] = src[0];
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dst[1] = src[1];
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dst[2] = src[2];
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dst[3] = src[3];
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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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dst[0] = src[0];
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dst[1] = src[1];
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dst[2] = src[2];
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dst[3] = src[3];
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dst[4] = src[4];
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dst[5] = src[5];
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dst[6] = src[6];
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dst[7] = src[7];
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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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dst += cnt;
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}
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c->out = dst;
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}
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/**
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* \brief decode LZO 1x compressed data
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* \param out output buffer
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* \param outlen size of output buffer, number of bytes left are returned here
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* \param in input buffer
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* \param inlen size of input buffer, number of bytes left are returned here
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* \return 0 on success, otherwise error flags, see lzo.h
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*
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* make sure all buffers are appropriately padded, in must provide
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* LZO_INPUT_PADDING, out must provide LZO_OUTPUT_PADDING additional bytes
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*/
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int lzo1x_decode(void *out, int *outlen, void *in, int *inlen) {
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enum {COPY, BACKPTR} state = COPY;
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int x;
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LZOContext c;
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c.in = in;
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c.in_end = (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 |= LZO_ERROR;
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}
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while (!c.error) {
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int cnt, back;
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if (x >> 4) {
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if (x >> 6) {
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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 >> 5) {
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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 |= LZO_ERROR;
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break;
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}
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}
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} else
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switch (state) {
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case COPY:
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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 >> 4)
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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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break;
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case BACKPTR:
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cnt = 0;
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back = (GETB(c) << 2) + (x >> 2) + 1;
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break;
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}
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copy_backptr(&c, back, cnt + 2);
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cnt = x & 3;
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state = cnt ? BACKPTR : COPY;
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if (cnt)
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copy(&c, cnt);
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x = GETB(c);
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if (c.in > c.in_end)
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c.error |= LZO_INPUT_DEPLETED;
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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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#ifdef TEST
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#include <stdio.h>
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#include <lzo/lzo1x.h>
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#include "log.h"
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#define MAXSZ (10*1024*1024)
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int main(int argc, char *argv[]) {
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FILE *in = fopen(argv[1], "rb");
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uint8_t *orig = av_malloc(MAXSZ + 16);
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uint8_t *comp = av_malloc(2*MAXSZ + 16);
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uint8_t *decomp = av_malloc(MAXSZ + 16);
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size_t s = fread(orig, 1, MAXSZ, in);
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lzo_uint clen = 0;
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long tmp[LZO1X_MEM_COMPRESS];
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int inlen, outlen;
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int i;
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av_log_level = AV_LOG_DEBUG;
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lzo1x_999_compress(orig, s, comp, &clen, tmp);
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for (i = 0; i < 300; i++) {
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START_TIMER
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inlen = clen; outlen = MAXSZ;
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if (lzo1x_decode(decomp, &outlen, comp, &inlen))
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av_log(NULL, AV_LOG_ERROR, "decompression error\n");
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STOP_TIMER("lzod")
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}
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if (memcmp(orig, decomp, s))
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av_log(NULL, AV_LOG_ERROR, "decompression incorrect\n");
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else
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av_log(NULL, AV_LOG_ERROR, "decompression ok\n");
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return 0;
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}
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#endif
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