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
25/**
26 * @file
27 * @brief CD Graphics Video Decoder
28 * @author Michael Tison
29 * @sa http://wiki.multimedia.cx/index.php?title=CD_Graphics
30 * @sa http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg
31 */
32
33/// default screen sizes
34#define CDG_FULL_WIDTH           300
35#define CDG_FULL_HEIGHT          216
36#define CDG_DISPLAY_WIDTH        294
37#define CDG_DISPLAY_HEIGHT       204
38#define CDG_BORDER_WIDTH           6
39#define CDG_BORDER_HEIGHT         12
40
41/// masks
42#define CDG_COMMAND             0x09
43#define CDG_MASK                0x3F
44
45/// instruction codes
46#define CDG_INST_MEMORY_PRESET     1
47#define CDG_INST_BORDER_PRESET     2
48#define CDG_INST_TILE_BLOCK        6
49#define CDG_INST_SCROLL_PRESET    20
50#define CDG_INST_SCROLL_COPY      24
51#define CDG_INST_LOAD_PAL_LO      30
52#define CDG_INST_LOAD_PAL_HIGH    31
53#define CDG_INST_TILE_BLOCK_XOR   38
54
55/// data sizes
56#define CDG_PACKET_SIZE           24
57#define CDG_DATA_SIZE             16
58#define CDG_TILE_HEIGHT           12
59#define CDG_TILE_WIDTH             6
60#define CDG_MINIMUM_PKT_SIZE       6
61#define CDG_MINIMUM_SCROLL_SIZE    3
62#define CDG_HEADER_SIZE            8
63#define CDG_PALETTE_SIZE          16
64
65typedef struct CDGraphicsContext {
66    AVFrame frame;
67    int hscroll;
68    int vscroll;
69} CDGraphicsContext;
70
71static void cdg_init_frame(AVFrame *frame)
72{
73    avcodec_get_frame_defaults(frame);
74    frame->reference = 3;
75    frame->buffer_hints = FF_BUFFER_HINTS_VALID    |
76                          FF_BUFFER_HINTS_READABLE |
77                          FF_BUFFER_HINTS_PRESERVE |
78                          FF_BUFFER_HINTS_REUSABLE;
79}
80
81static av_cold int cdg_decode_init(AVCodecContext *avctx)
82{
83    CDGraphicsContext *cc = avctx->priv_data;
84
85    cdg_init_frame(&cc->frame);
86
87    avctx->width   = CDG_FULL_WIDTH;
88    avctx->height  = CDG_FULL_HEIGHT;
89    avctx->pix_fmt = PIX_FMT_PAL8;
90
91    return 0;
92}
93
94static void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data)
95{
96    int y;
97    int lsize    = cc->frame.linesize[0];
98    uint8_t *buf = cc->frame.data[0];
99    int color    = data[0] & 0x0F;
100
101    if (!(data[1] & 0x0F)) {
102        /// fill the top and bottom borders
103        memset(buf, color, CDG_BORDER_HEIGHT * lsize);
104        memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,
105               color, CDG_BORDER_HEIGHT * lsize);
106
107        /// fill the side borders
108        for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {
109            memset(buf + y * lsize, color, CDG_BORDER_WIDTH);
110            memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,
111                   color, CDG_BORDER_WIDTH);
112        }
113    }
114}
115
116static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
117{
118    uint8_t r, g, b;
119    uint16_t color;
120    int i;
121    int array_offset  = low ? 0 : 8;
122    uint32_t *palette = (uint32_t *) cc->frame.data[1];
123
124    for (i = 0; i < 8; i++) {
125        color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);
126        r = ((color >> 8) & 0x000F) * 17;
127        g = ((color >> 4) & 0x000F) * 17;
128        b = ((color     ) & 0x000F) * 17;
129        palette[i + array_offset] = r << 16 | g << 8 | b;
130    }
131    cc->frame.palette_has_changed = 1;
132}
133
134static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b)
135{
136    unsigned ci, ri;
137    int color;
138    int x, y;
139    int ai;
140    int stride   = cc->frame.linesize[0];
141    uint8_t *buf = cc->frame.data[0];
142
143    ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
144    ci = (data[3] & 0x3F) * CDG_TILE_WIDTH  + cc->hscroll;
145
146    if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
147        return AVERROR(EINVAL);
148    if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
149        return AVERROR(EINVAL);
150
151    for (y = 0; y < CDG_TILE_HEIGHT; y++) {
152        for (x = 0; x < CDG_TILE_WIDTH; x++) {
153            if (!((data[4 + y] >> (5 - x)) & 0x01))
154                color = data[0] & 0x0F;
155            else
156                color = data[1] & 0x0F;
157
158            ai = ci + x + (stride * (ri + y));
159            if (b)
160                color ^= buf[ai];
161            buf[ai] = color;
162        }
163    }
164
165    return 0;
166}
167
168#define UP    2
169#define DOWN  1
170#define LEFT  2
171#define RIGHT 1
172
173static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
174                              int in_tl_x, int in_tl_y, uint8_t *in,
175                              int w, int h, int stride)
176{
177    int y;
178
179    in  += in_tl_x  + in_tl_y  * stride;
180    out += out_tl_x + out_tl_y * stride;
181    for (y = 0; y < h; y++)
182        memcpy(out + y * stride, in + y * stride, w);
183}
184
185static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
186                                 int color, int w, int h, int stride)
187{
188    int y;
189
190    for (y = tl_y; y < tl_y + h; y++)
191        memset(out + tl_x + y * stride, color, w);
192}
193
194static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
195                             int in_tl_x, int in_tl_y, uint8_t *in,
196                             int color, int w, int h, int stride, int roll)
197{
198    if (roll) {
199        cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
200                          in, w, h, stride);
201    } else {
202        cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
203    }
204}
205
206static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
207                       AVFrame *new_frame, int roll_over)
208{
209    int color;
210    int hscmd, h_off, hinc, vscmd, v_off, vinc;
211    int y;
212    int stride   = cc->frame.linesize[0];
213    uint8_t *in  = cc->frame.data[0];
214    uint8_t *out = new_frame->data[0];
215
216    color =  data[0] & 0x0F;
217    hscmd = (data[1] & 0x30) >> 4;
218    vscmd = (data[2] & 0x30) >> 4;
219
220    h_off =  FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH  - 1);
221    v_off =  FFMIN(data[2] & 0x07, CDG_BORDER_HEIGHT - 1);
222
223    /// find the difference and save the offset for cdg_tile_block usage
224    hinc = h_off - cc->hscroll;
225    vinc = v_off - cc->vscroll;
226    cc->hscroll = h_off;
227    cc->vscroll = v_off;
228
229    if (vscmd == UP)
230        vinc -= 12;
231    if (vscmd == DOWN)
232        vinc += 12;
233    if (hscmd == LEFT)
234        hinc -= 6;
235    if (hscmd == RIGHT)
236        hinc += 6;
237
238    if (!hinc && !vinc)
239        return;
240
241    memcpy(new_frame->data[1], cc->frame.data[1], CDG_PALETTE_SIZE * 4);
242
243    for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
244        memcpy(out + FFMAX(0, hinc) + stride * y,
245               in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
246               FFMIN(stride + hinc, stride));
247
248    if (vinc > 0)
249        cdg_fill_wrapper(0, 0, out,
250                         0, CDG_FULL_HEIGHT - vinc, in, color,
251                         stride, vinc, stride, roll_over);
252    else if (vinc < 0)
253        cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
254                         0, 0, in, color,
255                         stride, -1 * vinc, stride, roll_over);
256
257    if (hinc > 0)
258        cdg_fill_wrapper(0, 0, out,
259                         CDG_FULL_WIDTH - hinc, 0, in, color,
260                         hinc, CDG_FULL_HEIGHT, stride, roll_over);
261    else if (hinc < 0)
262        cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
263                         0, 0, in, color,
264                         -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
265
266}
267
268static int cdg_decode_frame(AVCodecContext *avctx,
269                            void *data, int *data_size, AVPacket *avpkt)
270{
271    const uint8_t *buf = avpkt->data;
272    int buf_size       = avpkt->size;
273    int ret;
274    uint8_t command, inst;
275    uint8_t cdg_data[CDG_DATA_SIZE];
276    AVFrame new_frame;
277    CDGraphicsContext *cc = avctx->priv_data;
278
279    if (buf_size < CDG_MINIMUM_PKT_SIZE) {
280        av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
281        return AVERROR(EINVAL);
282    }
283
284    ret = avctx->reget_buffer(avctx, &cc->frame);
285    if (ret) {
286        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
287        return ret;
288    }
289
290    command = bytestream_get_byte(&buf);
291    inst    = bytestream_get_byte(&buf);
292    inst    &= CDG_MASK;
293    buf += 2;  /// skipping 2 unneeded bytes
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            cdg_init_frame(&new_frame);
336            ret = avctx->get_buffer(avctx, &new_frame);
337            if (ret) {
338                av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
339                return ret;
340            }
341
342            cdg_scroll(cc, cdg_data, &new_frame, inst == CDG_INST_SCROLL_COPY);
343            avctx->release_buffer(avctx, &cc->frame);
344            cc->frame = new_frame;
345            break;
346        default:
347            break;
348        }
349
350        *data_size = sizeof(AVFrame);
351    } else {
352        *data_size = 0;
353        buf_size   = 0;
354    }
355
356    *(AVFrame *) data = cc->frame;
357    return buf_size;
358}
359
360static av_cold int cdg_decode_end(AVCodecContext *avctx)
361{
362    CDGraphicsContext *cc = avctx->priv_data;
363
364    if (cc->frame.data[0])
365        avctx->release_buffer(avctx, &cc->frame);
366
367    return 0;
368}
369
370AVCodec cdgraphics_decoder = {
371    "cdgraphics",
372    AVMEDIA_TYPE_VIDEO,
373    CODEC_ID_CDGRAPHICS,
374    sizeof(CDGraphicsContext),
375    cdg_decode_init,
376    NULL,
377    cdg_decode_end,
378    cdg_decode_frame,
379    CODEC_CAP_DR1,
380    .long_name = NULL_IF_CONFIG_SMALL("CD Graphics video"),
381};
382