aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/cdgraphics.c
blob: 8638dca931d029a31559c8b86ffae01283586810 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
/*
 * 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"

/**
 * @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_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;
} CDGraphicsContext;

static void cdg_init_frame(AVFrame *frame)
{
    avcodec_get_frame_defaults(frame);
    frame->reference = 3;
    frame->buffer_hints = FF_BUFFER_HINTS_VALID    |
                          FF_BUFFER_HINTS_READABLE |
                          FF_BUFFER_HINTS_PRESERVE |
                          FF_BUFFER_HINTS_REUSABLE;
}

static av_cold int cdg_decode_init(AVCodecContext *avctx)
{
    CDGraphicsContext *cc = avctx->priv_data;

    cdg_init_frame(&cc->frame);

    avctx->width   = CDG_FULL_WIDTH;
    avctx->height  = CDG_FULL_HEIGHT;
    avctx->pix_fmt = PIX_FMT_PAL8;

    return 0;
}

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] = 0xFF << 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] & 0x07, CDG_BORDER_HEIGHT - 1);

    /// find the difference and save the offset for cdg_tile_block usage
    hinc = h_off - cc->hscroll;
    vinc = v_off - cc->vscroll;
    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,
                            void *data, int *data_size, AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size       = avpkt->size;
    int ret;
    uint8_t command, inst;
    uint8_t cdg_data[CDG_DATA_SIZE];
    AVFrame new_frame;
    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);
    }

    ret = avctx->reget_buffer(avctx, &cc->frame);
    if (ret) {
        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
        return ret;
    }

    command = bytestream_get_byte(&buf);
    inst    = bytestream_get_byte(&buf);
    inst    &= CDG_MASK;
    buf += 2;  /// skipping 2 unneeded bytes
    bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);

    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);
            }

            cdg_init_frame(&new_frame);
            ret = avctx->get_buffer(avctx, &new_frame);
            if (ret) {
                av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
                return ret;
            }

            cdg_scroll(cc, cdg_data, &new_frame, inst == CDG_INST_SCROLL_COPY);
            avctx->release_buffer(avctx, &cc->frame);
            cc->frame = new_frame;
            break;
        default:
            break;
        }

        *data_size = sizeof(AVFrame);
    } else {
        *data_size = 0;
        buf_size   = 0;
    }

    *(AVFrame *) data = cc->frame;
    return buf_size;
}

static av_cold int cdg_decode_end(AVCodecContext *avctx)
{
    CDGraphicsContext *cc = avctx->priv_data;

    if (cc->frame.data[0])
        avctx->release_buffer(avctx, &cc->frame);

    return 0;
}

AVCodec ff_cdgraphics_decoder = {
    .name           = "cdgraphics",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_CDGRAPHICS,
    .priv_data_size = sizeof(CDGraphicsContext),
    .init           = cdg_decode_init,
    .close          = cdg_decode_end,
    .decode         = cdg_decode_frame,
    .capabilities   = CODEC_CAP_DR1,
    .long_name      = NULL_IF_CONFIG_SMALL("CD Graphics video"),
};