[Ffmpeg-cvslog] CVS: ffmpeg/libavcodec lzo.c, NONE, 1.1 lzo.h, NONE, 1.1 Makefile, 1.220, 1.221 cscd.c, 1.1, 1.2

Reimar Döffinger CVS reimar
Thu Jan 12 18:52:44 CET 2006


Update of /cvsroot/ffmpeg/ffmpeg/libavcodec
In directory mail:/var2/tmp/cvs-serv32374/libavcodec

Modified Files:
	Makefile cscd.c 
Added Files:
	lzo.c lzo.h 
Log Message:
Our own LZO (1X) implementation, under LGPL and optimized for readability.
Tested on CamStudio sample files.


--- NEW FILE: lzo.c ---
/*
 * LZO 1x decompression
 * Copyright (c) 2006 Reimar Doeffinger
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "common.h"
#include "lzo.h"

typedef struct LZOContext {
    uint8_t *in, *in_end;
    uint8_t *out, *out_end;
    int out_size;
    int error;
} LZOContext;

/**
 * \brief read one byte from input buffer, avoiding overrun
 * \return byte read
 */
static inline int get_byte(LZOContext *c) {
    if (c->in < c->in_end)
        return *c->in++;
    c->error |= LZO_INPUT_DEPLETED;
    return -1;
}

/**
 * \brief decode a length value in the coding used by lzo
 * \param x previous byte value
 * \param mask bits used from x
 * \return decoded length value
 */
static inline int get_len(LZOContext *c, int x, int mask) {
    int cnt = x & mask;
    if (!cnt) {
        while (!(x = get_byte(c))) cnt += 255;
        cnt += mask + x;
    }
    return cnt;
}

/**
 * \brief copy bytes from input to output buffer with checking
 * \param cnt number of bytes to copy, must be > 0
 */
static inline void copy(LZOContext *c, int cnt) {
    if (c->in + cnt > c->in_end) {
        cnt = c->in_end - c->in;
        c->error |= LZO_INPUT_DEPLETED;
    }
    if (c->out + cnt > c->out_end) {
        cnt = c->out_end - c->out;
        c->error |= LZO_OUTPUT_FULL;
    }
    do {
        *c->out++ = *c->in++;
    } while (--cnt);
}

/**
 * \brief copy previously decoded bytes to current position
 * \param back how many bytes back we start
 * \param cnt number of bytes to copy, must be > 0
 *
 * cnt > back is valid, this will copy the bytes we just copied.
 */
static inline void copy_backptr(LZOContext *c, int back, int cnt) {
    if (c->out - back < c->out_end - c->out_size) {
        c->error |= LZO_INVALID_BACKPTR;
        return;
    }
    if (c->out + cnt > c->out_end) {
        cnt = c->out_end - c->out;
        c->error |= LZO_OUTPUT_FULL;
    }
    do {
        *c->out++ = c->out[-back];
    } while (--cnt);
}

/**
 * \brief decode LZO 1x compressed data
 * \param out output buffer
 * \param outlen size of output buffer, number of bytes left are returned here
 * \param in input buffer
 * \param inlen size of input buffer, number of bytes left are returned here
 * \return 0 on success, otherwise error flags, see lzo.h
 */
int lzo1x_decode(void *out, int *outlen, void *in, int *inlen) {
    enum {COPY, BACKPTR} state = COPY;
    int x;
    LZOContext c;
    c.in = in;
    c.in_end = in + *inlen;
    c.out = out;
    c.out_end = out + * outlen;
    c.out_size = *outlen;
    c.error = 0;
    x = get_byte(&c);
    if (x > 17) {
        copy(&c, x - 17);
        x = get_byte(&c);
        if (x < 16) c.error |= LZO_ERROR;
    }
    while (!c.error) {
        int cnt, back;
        if (x >> 4) {
            state = BACKPTR;
            if (x >> 6) {
                cnt = (x >> 5) - 1;
                back = (get_byte(&c) << 3) + ((x >> 2) & 7) + 1;
            } else if (x >> 5) {
                cnt = get_len(&c, x, 31);
                x = get_byte(&c);
                back = (get_byte(&c) << 6) + (x >> 2) + 1;
            } else {
                cnt = get_len(&c, x, 7);
                back = (1 << 14) + ((x & 8) << 11);
                x = get_byte(&c);
                back += (get_byte(&c) << 6) + (x >> 2);
                if (back == (1 << 14)) {
                    if (cnt != 1)
                        c.error |= LZO_ERROR;
                    break;
                }
            }
        } else
        switch (state) {
            case COPY:
                cnt = get_len(&c, x, 15);
                copy(&c, cnt + 3);
                x = get_byte(&c);
                if (x >> 4)
                    continue;
                cnt = 1;
                back = (1 << 11) + (get_byte(&c) << 2) + (x >> 2) + 1;
                break;
            case BACKPTR:
                cnt = 0;
                back = (get_byte(&c) << 2) + (x >> 2) + 1;
                break;
        }
        copy_backptr(&c, back, cnt + 2);
        cnt = x & 3;
        if (cnt)
            copy(&c, cnt);
        else
            state = (state == COPY) ? BACKPTR : COPY;
        x = get_byte(&c);
    }
    *inlen = c.in_end - c.in;
    *outlen = c.out_end - c.out;
    return c.error;
}

--- NEW FILE: lzo.h ---
#ifndef _LZO_H
#define LZO_H

#define LZO_INPUT_DEPLETED 1
#define LZO_OUTPUT_FULL 2
#define LZO_INVALID_BACKPTR 4
#define LZO_ERROR 8

int lzo1x_decode(void *out, int *outlen, void *in, int *inlen);

#endif

Index: Makefile
===================================================================
RCS file: /cvsroot/ffmpeg/ffmpeg/libavcodec/Makefile,v
retrieving revision 1.220
retrieving revision 1.221
diff -u -d -r1.220 -r1.221
--- Makefile	11 Jan 2006 23:59:59 -0000	1.220
+++ Makefile	12 Jan 2006 17:52:41 -0000	1.221
@@ -169,6 +169,7 @@
 endif
 ifeq ($(CONFIG_CSCD_DECODER),yes)
     OBJS+= cscd.o
+    OBJS+= lzo.o
 endif
 ifeq ($(CONFIG_ULTI_DECODER),yes)
     OBJS+= ulti.o

Index: cscd.c
===================================================================
RCS file: /cvsroot/ffmpeg/ffmpeg/libavcodec/cscd.c,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -d -r1.1 -r1.2
--- cscd.c	9 Jan 2006 15:41:39 -0000	1.1
+++ cscd.c	12 Jan 2006 17:52:41 -0000	1.2
@@ -25,9 +25,7 @@
 #ifdef CONFIG_ZLIB
 #include <zlib.h>
 #endif
-#ifdef CONFIG_LZO
-#include <lzo1x.h>
-#endif
+#include "lzo.h"
 
 typedef struct {
     AVFrame pic;
@@ -158,16 +156,10 @@
     // decompress data
     switch ((buf[0] >> 1) & 7) {
         case 0: { // lzo compression
-#ifdef CONFIG_LZO
-            unsigned int dlen = c->decomp_size;
-            if (lzo1x_decompress_safe(&buf[2], buf_size - 2,
-                       c->decomp_buf, &dlen, NULL) != LZO_E_OK)
+            int outlen = c->decomp_size, inlen = buf_size - 2;
+            if (lzo1x_decode(c->decomp_buf, &outlen, &buf[2], &inlen))
                 av_log(avctx, AV_LOG_ERROR, "error during lzo decompression\n");
             break;
-#else
-            av_log(avctx, AV_LOG_ERROR, "compiled without lzo (GPL) support\n");
-            return -1;
-#endif
         }
         case 1: { // zlib compression
 #ifdef CONFIG_ZLIB





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