1/*
2 * CD Graphics Video Decoder
3 * Copyright (c) 2009 Michael Tison
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include "avcodec.h"
23#include "bytestream.h"
24#include "internal.h"
25
26/**
27 * @file
28 * @brief CD Graphics Video Decoder
29 * @author Michael Tison
30 * @see http://wiki.multimedia.cx/index.php?title=CD_Graphics
31 * @see http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg
32 */
33
34/// default screen sizes
35#define CDG_FULL_WIDTH           300
36#define CDG_FULL_HEIGHT          216
37#define CDG_DISPLAY_WIDTH        294
38#define CDG_DISPLAY_HEIGHT       204
39#define CDG_BORDER_WIDTH           6
40#define CDG_BORDER_HEIGHT         12
41
42/// masks
43#define CDG_COMMAND             0x09
44#define CDG_MASK                0x3F
45
46/// instruction codes
47#define CDG_INST_MEMORY_PRESET     1
48#define CDG_INST_BORDER_PRESET     2
49#define CDG_INST_TILE_BLOCK        6
50#define CDG_INST_SCROLL_PRESET    20
51#define CDG_INST_SCROLL_COPY      24
52#define CDG_INST_LOAD_PAL_LO      30
53#define CDG_INST_LOAD_PAL_HIGH    31
54#define CDG_INST_TILE_BLOCK_XOR   38
55
56/// data sizes
57#define CDG_PACKET_SIZE           24
58#define CDG_DATA_SIZE             16
59#define CDG_TILE_HEIGHT           12
60#define CDG_TILE_WIDTH             6
61#define CDG_MINIMUM_PKT_SIZE       6
62#define CDG_MINIMUM_SCROLL_SIZE    3
63#define CDG_HEADER_SIZE            8
64#define CDG_PALETTE_SIZE          16
65
66typedef struct CDGraphicsContext {
67    AVFrame *frame;
68    int hscroll;
69    int vscroll;
70} CDGraphicsContext;
71
72static av_cold int cdg_decode_init(AVCodecContext *avctx)
73{
74    CDGraphicsContext *cc = avctx->priv_data;
75
76    cc->frame = av_frame_alloc();
77    if (!cc->frame)
78        return AVERROR(ENOMEM);
79
80    avctx->width   = CDG_FULL_WIDTH;
81    avctx->height  = CDG_FULL_HEIGHT;
82    avctx->pix_fmt = AV_PIX_FMT_PAL8;
83
84    return 0;
85}
86
87static void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data)
88{
89    int y;
90    int lsize    = cc->frame->linesize[0];
91    uint8_t *buf = cc->frame->data[0];
92    int color    = data[0] & 0x0F;
93
94    if (!(data[1] & 0x0F)) {
95        /// fill the top and bottom borders
96        memset(buf, color, CDG_BORDER_HEIGHT * lsize);
97        memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,
98               color, CDG_BORDER_HEIGHT * lsize);
99
100        /// fill the side borders
101        for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {
102            memset(buf + y * lsize, color, CDG_BORDER_WIDTH);
103            memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,
104                   color, CDG_BORDER_WIDTH);
105        }
106    }
107}
108
109static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
110{
111    uint8_t r, g, b;
112    uint16_t color;
113    int i;
114    int array_offset  = low ? 0 : 8;
115    uint32_t *palette = (uint32_t *) cc->frame->data[1];
116
117    for (i = 0; i < 8; i++) {
118        color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);
119        r = ((color >> 8) & 0x000F) * 17;
120        g = ((color >> 4) & 0x000F) * 17;
121        b = ((color     ) & 0x000F) * 17;
122        palette[i + array_offset] = 0xFFU << 24 | r << 16 | g << 8 | b;
123    }
124    cc->frame->palette_has_changed = 1;
125}
126
127static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b)
128{
129    unsigned ci, ri;
130    int color;
131    int x, y;
132    int ai;
133    int stride   = cc->frame->linesize[0];
134    uint8_t *buf = cc->frame->data[0];
135
136    ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
137    ci = (data[3] & 0x3F) * CDG_TILE_WIDTH  + cc->hscroll;
138
139    if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
140        return AVERROR(EINVAL);
141    if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
142        return AVERROR(EINVAL);
143
144    for (y = 0; y < CDG_TILE_HEIGHT; y++) {
145        for (x = 0; x < CDG_TILE_WIDTH; x++) {
146            if (!((data[4 + y] >> (5 - x)) & 0x01))
147                color = data[0] & 0x0F;
148            else
149                color = data[1] & 0x0F;
150
151            ai = ci + x + (stride * (ri + y));
152            if (b)
153                color ^= buf[ai];
154            buf[ai] = color;
155        }
156    }
157
158    return 0;
159}
160
161#define UP    2
162#define DOWN  1
163#define LEFT  2
164#define RIGHT 1
165
166static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
167                              int in_tl_x, int in_tl_y, uint8_t *in,
168                              int w, int h, int stride)
169{
170    int y;
171
172    in  += in_tl_x  + in_tl_y  * stride;
173    out += out_tl_x + out_tl_y * stride;
174    for (y = 0; y < h; y++)
175        memcpy(out + y * stride, in + y * stride, w);
176}
177
178static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
179                                 int color, int w, int h, int stride)
180{
181    int y;
182
183    for (y = tl_y; y < tl_y + h; y++)
184        memset(out + tl_x + y * stride, color, w);
185}
186
187static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
188                             int in_tl_x, int in_tl_y, uint8_t *in,
189                             int color, int w, int h, int stride, int roll)
190{
191    if (roll) {
192        cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
193                          in, w, h, stride);
194    } else {
195        cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
196    }
197}
198
199static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
200                       AVFrame *new_frame, int roll_over)
201{
202    int color;
203    int hscmd, h_off, hinc, vscmd, v_off, vinc;
204    int y;
205    int stride   = cc->frame->linesize[0];
206    uint8_t *in  = cc->frame->data[0];
207    uint8_t *out = new_frame->data[0];
208
209    color =  data[0] & 0x0F;
210    hscmd = (data[1] & 0x30) >> 4;
211    vscmd = (data[2] & 0x30) >> 4;
212
213    h_off =  FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH  - 1);
214    v_off =  FFMIN(data[2] & 0x0F, CDG_BORDER_HEIGHT - 1);
215
216    /// find the difference and save the offset for cdg_tile_block usage
217    hinc = h_off - cc->hscroll;
218    vinc = v_off - cc->vscroll;
219    cc->hscroll = h_off;
220    cc->vscroll = v_off;
221
222    if (vscmd == UP)
223        vinc -= 12;
224    if (vscmd == DOWN)
225        vinc += 12;
226    if (hscmd == LEFT)
227        hinc -= 6;
228    if (hscmd == RIGHT)
229        hinc += 6;
230
231    if (!hinc && !vinc)
232        return;
233
234    memcpy(new_frame->data[1], cc->frame->data[1], CDG_PALETTE_SIZE * 4);
235
236    for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
237        memcpy(out + FFMAX(0, hinc) + stride * y,
238               in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
239               FFMIN(stride + hinc, stride));
240
241    if (vinc > 0)
242        cdg_fill_wrapper(0, 0, out,
243                         0, CDG_FULL_HEIGHT - vinc, in, color,
244                         stride, vinc, stride, roll_over);
245    else if (vinc < 0)
246        cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
247                         0, 0, in, color,
248                         stride, -1 * vinc, stride, roll_over);
249
250    if (hinc > 0)
251        cdg_fill_wrapper(0, 0, out,
252                         CDG_FULL_WIDTH - hinc, 0, in, color,
253                         hinc, CDG_FULL_HEIGHT, stride, roll_over);
254    else if (hinc < 0)
255        cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
256                         0, 0, in, color,
257                         -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
258
259}
260
261static int cdg_decode_frame(AVCodecContext *avctx,
262                            void *data, int *got_frame, AVPacket *avpkt)
263{
264    const uint8_t *buf = avpkt->data;
265    int buf_size       = avpkt->size;
266    int ret;
267    uint8_t command, inst;
268    uint8_t cdg_data[CDG_DATA_SIZE] = {0};
269    AVFrame *frame = data;
270    CDGraphicsContext *cc = avctx->priv_data;
271
272    if (buf_size < CDG_MINIMUM_PKT_SIZE) {
273        av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
274        return AVERROR(EINVAL);
275    }
276    if (buf_size > CDG_HEADER_SIZE + CDG_DATA_SIZE) {
277        av_log(avctx, AV_LOG_ERROR, "buffer too big for decoder\n");
278        return AVERROR(EINVAL);
279    }
280
281    if ((ret = ff_reget_buffer(avctx, cc->frame)) < 0)
282        return ret;
283    if (!avctx->frame_number) {
284        memset(cc->frame->data[0], 0, cc->frame->linesize[0] * avctx->height);
285        memset(cc->frame->data[1], 0, AVPALETTE_SIZE);
286    }
287
288    command = bytestream_get_byte(&buf);
289    inst    = bytestream_get_byte(&buf);
290    inst    &= CDG_MASK;
291    buf += 2;  /// skipping 2 unneeded bytes
292
293    if (buf_size > CDG_HEADER_SIZE)
294        bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);
295
296    if ((command & CDG_MASK) == CDG_COMMAND) {
297        switch (inst) {
298        case CDG_INST_MEMORY_PRESET:
299            if (!(cdg_data[1] & 0x0F))
300                memset(cc->frame->data[0], cdg_data[0] & 0x0F,
301                       cc->frame->linesize[0] * CDG_FULL_HEIGHT);
302            break;
303        case CDG_INST_LOAD_PAL_LO:
304        case CDG_INST_LOAD_PAL_HIGH:
305            if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
306                av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n");
307                return AVERROR(EINVAL);
308            }
309
310            cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);
311            break;
312        case CDG_INST_BORDER_PRESET:
313            cdg_border_preset(cc, cdg_data);
314            break;
315        case CDG_INST_TILE_BLOCK_XOR:
316        case CDG_INST_TILE_BLOCK:
317            if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
318                av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n");
319                return AVERROR(EINVAL);
320            }
321
322            ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);
323            if (ret) {
324                av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");
325                return ret;
326            }
327            break;
328        case CDG_INST_SCROLL_PRESET:
329        case CDG_INST_SCROLL_COPY:
330            if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) {
331                av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n");
332                return AVERROR(EINVAL);
333            }
334
335            if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
336                return ret;
337
338            cdg_scroll(cc, cdg_data, frame, inst == CDG_INST_SCROLL_COPY);
339            av_frame_unref(cc->frame);
340            ret = av_frame_ref(cc->frame, frame);
341            if (ret < 0)
342                return ret;
343            break;
344        default:
345            break;
346        }
347
348        if (!frame->data[0]) {
349            ret = av_frame_ref(frame, cc->frame);
350            if (ret < 0)
351                return ret;
352        }
353        *got_frame = 1;
354    } else {
355        *got_frame = 0;
356    }
357
358    return avpkt->size;
359}
360
361static av_cold int cdg_decode_end(AVCodecContext *avctx)
362{
363    CDGraphicsContext *cc = avctx->priv_data;
364
365    av_frame_free(&cc->frame);
366
367    return 0;
368}
369
370AVCodec ff_cdgraphics_decoder = {
371    .name           = "cdgraphics",
372    .long_name      = NULL_IF_CONFIG_SMALL("CD Graphics video"),
373    .type           = AVMEDIA_TYPE_VIDEO,
374    .id             = AV_CODEC_ID_CDGRAPHICS,
375    .priv_data_size = sizeof(CDGraphicsContext),
376    .init           = cdg_decode_init,
377    .close          = cdg_decode_end,
378    .decode         = cdg_decode_frame,
379    .capabilities   = CODEC_CAP_DR1,
380};
381