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FFmpeg/libavcodec/bmvvideo.c
Andreas Rheinhardt a247ac640d avcodec: Constify AVCodecs 
Given that the AVCodec.next pointer has now been removed, most of the
AVCodecs are not modified at all any more and can therefore be made
const (as this patch does); the only exceptions are the very few codecs
for external libraries that have a init_static_data callback.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>
2021-04-27 10:43:15 -03:00

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/*
* Discworld II BMV video decoder
* Copyright (c) 2011 Konstantin Shishkov
*
* This file is part of FFmpeg.
*
* FFmpeg 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 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/avassert.h"
#include "libavutil/common.h"
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
enum BMVFlags{
BMV_NOP = 0,
BMV_END,
BMV_DELTA,
BMV_INTRA,
BMV_SCROLL = 0x04,
BMV_PALETTE = 0x08,
BMV_COMMAND = 0x10,
BMV_AUDIO = 0x20,
BMV_EXT = 0x40,
BMV_PRINT = 0x80
};
#define SCREEN_WIDE 640
#define SCREEN_HIGH 429
typedef struct BMVDecContext {
AVCodecContext *avctx;
uint8_t *frame, frame_base[SCREEN_WIDE * (SCREEN_HIGH + 1)];
uint32_t pal[256];
const uint8_t *stream;
} BMVDecContext;
#define NEXT_BYTE(v) (v) = forward ? (v) + 1 : (v) - 1;
static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
{
unsigned val, saved_val = 0;
int tmplen = src_len;
const uint8_t *src, *source_end = source + src_len;
uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH;
uint8_t *dst, *dst_end;
int len, mask;
int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0);
int read_two_nibbles, flag;
int advance_mode;
int mode = 0;
int i;
if (src_len <= 0)
return AVERROR_INVALIDDATA;
if (forward) {
src = source;
dst = frame;
dst_end = frame_end;
} else {
src = source + src_len - 1;
dst = frame_end - 1;
dst_end = frame - 1;
}
for (;;) {
int shift = 0;
flag = 0;
/* The mode/len decoding is a bit strange:
* values are coded as variable-length codes with nibble units,
* code end is signalled by two top bits in the nibble being nonzero.
* And since data is bytepacked and we read two nibbles at a time,
* we may get a nibble belonging to the next code.
* Hence this convoluted loop.
*/
if (!mode || (tmplen == 4)) {
if (src < source || src >= source_end)
return AVERROR_INVALIDDATA;
val = *src;
read_two_nibbles = 1;
} else {
val = saved_val;
read_two_nibbles = 0;
}
if (!(val & 0xC)) {
for (;;) {
if(shift>22)
return -1;
if (!read_two_nibbles) {
if (src < source || src >= source_end)
return AVERROR_INVALIDDATA;
shift += 2;
val |= (unsigned)*src << shift;
if (*src & 0xC)
break;
}
// two upper bits of the nibble is zero,
// so shift top nibble value down into their place
read_two_nibbles = 0;
shift += 2;
mask = (1 << shift) - 1;
val = ((val >> 2) & ~mask) | (val & mask);
NEXT_BYTE(src);
if ((val & (0xC << shift))) {
flag = 1;
break;
}
}
} else if (mode) {
flag = tmplen != 4;
}
if (flag) {
tmplen = 4;
} else {
saved_val = val >> (4 + shift);
tmplen = 0;
val &= (1 << (shift + 4)) - 1;
NEXT_BYTE(src);
}
advance_mode = val & 1;
len = (val >> 1) - 1;
av_assert0(len>0);
mode += 1 + advance_mode;
if (mode >= 4)
mode -= 3;
if (len <= 0 || FFABS(dst_end - dst) < len)
return AVERROR_INVALIDDATA;
switch (mode) {
case 1:
if (forward) {
if (dst - frame + SCREEN_WIDE < frame_off ||
dst - frame + SCREEN_WIDE + frame_off < 0 ||
frame_end - dst < frame_off + len ||
frame_end - dst < len)
return AVERROR_INVALIDDATA;
for (i = 0; i < len; i++)
dst[i] = dst[frame_off + i];
dst += len;
} else {
dst -= len;
if (dst - frame + SCREEN_WIDE < frame_off ||
dst - frame + SCREEN_WIDE + frame_off < 0 ||
frame_end - dst < frame_off + len ||
frame_end - dst < len)
return AVERROR_INVALIDDATA;
for (i = len - 1; i >= 0; i--)
dst[i] = dst[frame_off + i];
}
break;
case 2:
if (forward) {
if (source + src_len - src < len)
return AVERROR_INVALIDDATA;
memcpy(dst, src, len);
dst += len;
src += len;
} else {
if (src - source < len)
return AVERROR_INVALIDDATA;
dst -= len;
src -= len;
memcpy(dst, src, len);
}
break;
case 3:
val = forward ? dst[-1] : dst[1];
if (forward) {
memset(dst, val, len);
dst += len;
} else {
dst -= len;
memset(dst, val, len);
}
break;
}
if (dst == dst_end)
return 0;
}
}
static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
AVPacket *pkt)
{
BMVDecContext * const c = avctx->priv_data;
AVFrame *frame = data;
int type, scr_off;
int i, ret;
uint8_t *srcptr, *outptr;
c->stream = pkt->data;
type = bytestream_get_byte(&c->stream);
if (type & BMV_AUDIO) {
int blobs = bytestream_get_byte(&c->stream);
if (pkt->size < blobs * 65 + 2) {
av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n");
return AVERROR_INVALIDDATA;
}
c->stream += blobs * 65;
}
if (type & BMV_COMMAND) {
int command_size = (type & BMV_PRINT) ? 8 : 10;
if (c->stream - pkt->data + command_size > pkt->size) {
av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n");
return AVERROR_INVALIDDATA;
}
c->stream += command_size;
}
if (type & BMV_PALETTE) {
if (c->stream - pkt->data > pkt->size - 768) {
av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n");
return AVERROR_INVALIDDATA;
}
for (i = 0; i < 256; i++)
c->pal[i] = 0xFFU << 24 | bytestream_get_be24(&c->stream);
}
if (type & BMV_SCROLL) {
if (c->stream - pkt->data > pkt->size - 2) {
av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n");
return AVERROR_INVALIDDATA;
}
scr_off = (int16_t)bytestream_get_le16(&c->stream);
} else if ((type & BMV_INTRA) == BMV_INTRA) {
scr_off = -640;
} else {
scr_off = 0;
}
if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
return ret;
if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) {
av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n");
return AVERROR_INVALIDDATA;
}
memcpy(frame->data[1], c->pal, AVPALETTE_SIZE);
frame->palette_has_changed = type & BMV_PALETTE;
outptr = frame->data[0];
srcptr = c->frame;
for (i = 0; i < avctx->height; i++) {
memcpy(outptr, srcptr, avctx->width);
srcptr += avctx->width;
outptr += frame->linesize[0];
}
*got_frame = 1;
/* always report that the buffer was completely consumed */
return pkt->size;
}
static av_cold int decode_init(AVCodecContext *avctx)
{
BMVDecContext * const c = avctx->priv_data;
c->avctx = avctx;
avctx->pix_fmt = AV_PIX_FMT_PAL8;
if (avctx->width != SCREEN_WIDE || avctx->height != SCREEN_HIGH) {
av_log(avctx, AV_LOG_ERROR, "Invalid dimension %dx%d\n", avctx->width, avctx->height);
return AVERROR_INVALIDDATA;
}
c->frame = c->frame_base + 640;
return 0;
}
const AVCodec ff_bmv_video_decoder = {
.name = "bmv_video",
.long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV video"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_BMV_VIDEO,
.priv_data_size = sizeof(BMVDecContext),
.init = decode_init,
.decode = decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
};
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