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FFmpeg/libavcodec/cdgraphics.c
Andreas Rheinhardt 4243da4ff4 avcodec/codec_internal: Use union for FFCodec decode/encode callbacks 
This is possible, because every given FFCodec has to implement
exactly one of these. Doing so decreases sizeof(FFCodec) and
therefore decreases the size of the binary.
Notice that in case of position-independent code the decrease
is in .data.rel.ro, so that this translates to decreased
memory consumption.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-04-05 20:02:37 +02:00

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/*
* CD Graphics Video Decoder
* Copyright (c) 2009 Michael Tison
*
* 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 "avcodec.h"
#include "bytestream.h"
#include "codec_internal.h"
#include "internal.h"
/**
* @file
* @brief CD Graphics Video Decoder
* @author Michael Tison
* @see http://wiki.multimedia.cx/index.php?title=CD_Graphics
* @see http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg
*/
/// default screen sizes
#define CDG_FULL_WIDTH 300
#define CDG_FULL_HEIGHT 216
#define CDG_DISPLAY_WIDTH 294
#define CDG_DISPLAY_HEIGHT 204
#define CDG_BORDER_WIDTH 6
#define CDG_BORDER_HEIGHT 12
/// masks
#define CDG_COMMAND 0x09
#define CDG_MASK 0x3F
/// instruction codes
#define CDG_INST_MEMORY_PRESET 1
#define CDG_INST_BORDER_PRESET 2
#define CDG_INST_TILE_BLOCK 6
#define CDG_INST_SCROLL_PRESET 20
#define CDG_INST_SCROLL_COPY 24
#define CDG_INST_TRANSPARENT_COL 28
#define CDG_INST_LOAD_PAL_LO 30
#define CDG_INST_LOAD_PAL_HIGH 31
#define CDG_INST_TILE_BLOCK_XOR 38
/// data sizes
#define CDG_PACKET_SIZE 24
#define CDG_DATA_SIZE 16
#define CDG_TILE_HEIGHT 12
#define CDG_TILE_WIDTH 6
#define CDG_MINIMUM_PKT_SIZE 6
#define CDG_MINIMUM_SCROLL_SIZE 3
#define CDG_HEADER_SIZE 8
#define CDG_PALETTE_SIZE 16
typedef struct CDGraphicsContext {
AVFrame *frame;
int hscroll;
int vscroll;
uint8_t alpha[CDG_PALETTE_SIZE];
int cleared;
} CDGraphicsContext;
static av_cold int cdg_decode_init(AVCodecContext *avctx)
{
CDGraphicsContext *cc = avctx->priv_data;
cc->frame = av_frame_alloc();
if (!cc->frame)
return AVERROR(ENOMEM);
for (int i = 0; i < CDG_PALETTE_SIZE; i++)
cc->alpha[i] = 0xFFU;
avctx->pix_fmt = AV_PIX_FMT_PAL8;
return ff_set_dimensions(avctx, CDG_FULL_WIDTH, CDG_FULL_HEIGHT);
}
static void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data)
{
int y;
int lsize = cc->frame->linesize[0];
uint8_t *buf = cc->frame->data[0];
int color = data[0] & 0x0F;
if (!(data[1] & 0x0F)) {
/// fill the top and bottom borders
memset(buf, color, CDG_BORDER_HEIGHT * lsize);
memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,
color, CDG_BORDER_HEIGHT * lsize);
/// fill the side borders
for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {
memset(buf + y * lsize, color, CDG_BORDER_WIDTH);
memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,
color, CDG_BORDER_WIDTH);
}
}
}
static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
{
uint8_t r, g, b;
uint16_t color;
int i;
int array_offset = low ? 0 : 8;
uint32_t *palette = (uint32_t *) cc->frame->data[1];
for (i = 0; i < 8; i++) {
color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);
r = ((color >> 8) & 0x000F) * 17;
g = ((color >> 4) & 0x000F) * 17;
b = ((color ) & 0x000F) * 17;
palette[i + array_offset] = (uint32_t)cc->alpha[i + array_offset] << 24 | r << 16 | g << 8 | b;
}
cc->frame->palette_has_changed = 1;
}
static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b)
{
unsigned ci, ri;
int color;
int x, y;
int ai;
int stride = cc->frame->linesize[0];
uint8_t *buf = cc->frame->data[0];
ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
ci = (data[3] & 0x3F) * CDG_TILE_WIDTH + cc->hscroll;
if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
return AVERROR(EINVAL);
if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
return AVERROR(EINVAL);
for (y = 0; y < CDG_TILE_HEIGHT; y++) {
for (x = 0; x < CDG_TILE_WIDTH; x++) {
if (!((data[4 + y] >> (5 - x)) & 0x01))
color = data[0] & 0x0F;
else
color = data[1] & 0x0F;
ai = ci + x + (stride * (ri + y));
if (b)
color ^= buf[ai];
buf[ai] = color;
}
}
return 0;
}
#define UP 2
#define DOWN 1
#define LEFT 2
#define RIGHT 1
static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
int in_tl_x, int in_tl_y, uint8_t *in,
int w, int h, int stride)
{
int y;
in += in_tl_x + in_tl_y * stride;
out += out_tl_x + out_tl_y * stride;
for (y = 0; y < h; y++)
memcpy(out + y * stride, in + y * stride, w);
}
static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
int color, int w, int h, int stride)
{
int y;
for (y = tl_y; y < tl_y + h; y++)
memset(out + tl_x + y * stride, color, w);
}
static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
int in_tl_x, int in_tl_y, uint8_t *in,
int color, int w, int h, int stride, int roll)
{
if (roll) {
cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
in, w, h, stride);
} else {
cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
}
}
static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
AVFrame *new_frame, int roll_over)
{
int color;
int hscmd, h_off, hinc, vscmd, v_off, vinc;
int y;
int stride = cc->frame->linesize[0];
uint8_t *in = cc->frame->data[0];
uint8_t *out = new_frame->data[0];
color = data[0] & 0x0F;
hscmd = (data[1] & 0x30) >> 4;
vscmd = (data[2] & 0x30) >> 4;
h_off = FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH - 1);
v_off = FFMIN(data[2] & 0x0F, CDG_BORDER_HEIGHT - 1);
/// find the difference and save the offset for cdg_tile_block usage
hinc = h_off - cc->hscroll;
vinc = cc->vscroll - v_off;
cc->hscroll = h_off;
cc->vscroll = v_off;
if (vscmd == UP)
vinc -= 12;
if (vscmd == DOWN)
vinc += 12;
if (hscmd == LEFT)
hinc -= 6;
if (hscmd == RIGHT)
hinc += 6;
if (!hinc && !vinc)
return;
memcpy(new_frame->data[1], cc->frame->data[1], CDG_PALETTE_SIZE * 4);
for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
memcpy(out + FFMAX(0, hinc) + stride * y,
in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
FFMIN(stride + hinc, stride));
if (vinc > 0)
cdg_fill_wrapper(0, 0, out,
0, CDG_FULL_HEIGHT - vinc, in, color,
stride, vinc, stride, roll_over);
else if (vinc < 0)
cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
0, 0, in, color,
stride, -1 * vinc, stride, roll_over);
if (hinc > 0)
cdg_fill_wrapper(0, 0, out,
CDG_FULL_WIDTH - hinc, 0, in, color,
hinc, CDG_FULL_HEIGHT, stride, roll_over);
else if (hinc < 0)
cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
0, 0, in, color,
-1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
}
static int cdg_decode_frame(AVCodecContext *avctx, AVFrame *frame,
int *got_frame, AVPacket *avpkt)
{
GetByteContext gb;
int buf_size = avpkt->size;
int ret;
uint8_t command, inst;
uint8_t cdg_data[CDG_DATA_SIZE] = {0};
CDGraphicsContext *cc = avctx->priv_data;
if (buf_size < CDG_MINIMUM_PKT_SIZE) {
av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
return AVERROR(EINVAL);
}
if (buf_size > CDG_HEADER_SIZE + CDG_DATA_SIZE) {
av_log(avctx, AV_LOG_ERROR, "buffer too big for decoder\n");
return AVERROR(EINVAL);
}
bytestream2_init(&gb, avpkt->data, avpkt->size);
if ((ret = ff_reget_buffer(avctx, cc->frame, 0)) < 0)
return ret;
if (!cc->cleared) {
memset(cc->frame->data[0], 0, cc->frame->linesize[0] * avctx->height);
memset(cc->frame->data[1], 0, AVPALETTE_SIZE);
cc->cleared = 1;
}
command = bytestream2_get_byte(&gb);
inst = bytestream2_get_byte(&gb);
inst &= CDG_MASK;
bytestream2_skip(&gb, 2);
bytestream2_get_buffer(&gb, cdg_data, sizeof(cdg_data));
if ((command & CDG_MASK) == CDG_COMMAND) {
switch (inst) {
case CDG_INST_MEMORY_PRESET:
if (!(cdg_data[1] & 0x0F))
memset(cc->frame->data[0], cdg_data[0] & 0x0F,
cc->frame->linesize[0] * CDG_FULL_HEIGHT);
break;
case CDG_INST_LOAD_PAL_LO:
case CDG_INST_LOAD_PAL_HIGH:
if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n");
return AVERROR(EINVAL);
}
cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);
break;
case CDG_INST_BORDER_PRESET:
cdg_border_preset(cc, cdg_data);
break;
case CDG_INST_TILE_BLOCK_XOR:
case CDG_INST_TILE_BLOCK:
if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n");
return AVERROR(EINVAL);
}
ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);
if (ret) {
av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");
return ret;
}
break;
case CDG_INST_SCROLL_PRESET:
case CDG_INST_SCROLL_COPY:
if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) {
av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n");
return AVERROR(EINVAL);
}
if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
return ret;
cdg_scroll(cc, cdg_data, frame, inst == CDG_INST_SCROLL_COPY);
av_frame_unref(cc->frame);
ret = av_frame_ref(cc->frame, frame);
if (ret < 0)
return ret;
break;
case CDG_INST_TRANSPARENT_COL:
for (int i = 0; i < CDG_PALETTE_SIZE; i++)
cc->alpha[i] = 255 - ((cdg_data[i] & 0x3f) << 2);
break;
default:
break;
}
if (!frame->data[0]) {
ret = av_frame_ref(frame, cc->frame);
if (ret < 0)
return ret;
}
*got_frame = 1;
} else {
*got_frame = 0;
}
return avpkt->size;
}
static void cdg_decode_flush(AVCodecContext *avctx)
{
CDGraphicsContext *cc = avctx->priv_data;
if (!cc->frame->data[0])
return;
memset(cc->frame->data[0], 0, cc->frame->linesize[0] * avctx->height);
if (!avctx->frame_number)
memset(cc->frame->data[1], 0, AVPALETTE_SIZE);
}
static av_cold int cdg_decode_end(AVCodecContext *avctx)
{
CDGraphicsContext *cc = avctx->priv_data;
av_frame_free(&cc->frame);
return 0;
}
const FFCodec ff_cdgraphics_decoder = {
.p.name = "cdgraphics",
.p.long_name = NULL_IF_CONFIG_SMALL("CD Graphics video"),
.p.type = AVMEDIA_TYPE_VIDEO,
.p.id = AV_CODEC_ID_CDGRAPHICS,
.priv_data_size = sizeof(CDGraphicsContext),
.init = cdg_decode_init,
.close = cdg_decode_end,
FF_CODEC_DECODE_CB(cdg_decode_frame),
.flush = cdg_decode_flush,
.p.capabilities = AV_CODEC_CAP_DR1,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
};
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