1/*
2 * Interplay C93 video decoder
3 * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
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
25typedef struct {
26    AVFrame pictures[2];
27    int currentpic;
28} C93DecoderContext;
29
30typedef enum {
31    C93_8X8_FROM_PREV  = 0x02,
32    C93_4X4_FROM_PREV  = 0x06,
33    C93_4X4_FROM_CURR  = 0x07,
34    C93_8X8_2COLOR     = 0x08,
35    C93_4X4_2COLOR     = 0x0A,
36    C93_4X4_4COLOR_GRP = 0x0B,
37    C93_4X4_4COLOR     = 0x0D,
38    C93_NOOP           = 0x0E,
39    C93_8X8_INTRA      = 0x0F,
40} C93BlockType;
41
42#define WIDTH   320
43#define HEIGHT  192
44
45#define C93_HAS_PALETTE 0x01
46#define C93_FIRST_FRAME 0x02
47
48static av_cold int decode_init(AVCodecContext *avctx)
49{
50    avctx->pix_fmt = PIX_FMT_PAL8;
51    return 0;
52}
53
54static av_cold int decode_end(AVCodecContext *avctx)
55{
56    C93DecoderContext * const c93 = avctx->priv_data;
57
58    if (c93->pictures[0].data[0])
59        avctx->release_buffer(avctx, &c93->pictures[0]);
60    if (c93->pictures[1].data[0])
61        avctx->release_buffer(avctx, &c93->pictures[1]);
62    return 0;
63}
64
65static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
66        uint8_t *from, int offset, int height, int stride)
67{
68    int i;
69    int width = height;
70    int from_x = offset % WIDTH;
71    int from_y = offset / WIDTH;
72    int overflow = from_x + width - WIDTH;
73
74    if (!from) {
75        /* silently ignoring predictive blocks in first frame */
76        return 0;
77    }
78
79    if (from_y + height > HEIGHT) {
80        av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
81               offset);
82        return -1;
83    }
84
85    if (overflow > 0) {
86        width -= overflow;
87        for (i = 0; i < height; i++) {
88            memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
89        }
90    }
91
92    for (i = 0; i < height; i++) {
93        memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
94    }
95
96    return 0;
97}
98
99static inline void draw_n_color(uint8_t *out, int stride, int width,
100         int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
101{
102    int x, y;
103    for (y = 0; y < height; y++) {
104        if (grps)
105            cols[0] = grps[3 * (y >> 1)];
106        for (x = 0; x < width; x++) {
107            if (grps)
108                cols[1]= grps[(x >> 1) + 1];
109            out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
110            col >>= bpp;
111        }
112    }
113}
114
115static int decode_frame(AVCodecContext *avctx, void *data,
116                            int *data_size, AVPacket *avpkt)
117{
118    const uint8_t *buf = avpkt->data;
119    int buf_size = avpkt->size;
120    C93DecoderContext * const c93 = avctx->priv_data;
121    AVFrame * const newpic = &c93->pictures[c93->currentpic];
122    AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
123    AVFrame *picture = data;
124    uint8_t *out;
125    int stride, i, x, y, bt = 0;
126
127    c93->currentpic ^= 1;
128
129    newpic->reference = 1;
130    newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
131                         FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
132    if (avctx->reget_buffer(avctx, newpic)) {
133        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
134        return -1;
135    }
136
137    stride = newpic->linesize[0];
138
139    if (buf[0] & C93_FIRST_FRAME) {
140        newpic->pict_type = FF_I_TYPE;
141        newpic->key_frame = 1;
142    } else {
143        newpic->pict_type = FF_P_TYPE;
144        newpic->key_frame = 0;
145    }
146
147    if (*buf++ & C93_HAS_PALETTE) {
148        uint32_t *palette = (uint32_t *) newpic->data[1];
149        const uint8_t *palbuf = buf + buf_size - 768 - 1;
150        for (i = 0; i < 256; i++) {
151            palette[i] = bytestream_get_be24(&palbuf);
152        }
153    } else {
154        if (oldpic->data[1])
155            memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
156    }
157
158    for (y = 0; y < HEIGHT; y += 8) {
159        out = newpic->data[0] + y * stride;
160        for (x = 0; x < WIDTH; x += 8) {
161            uint8_t *copy_from = oldpic->data[0];
162            unsigned int offset, j;
163            uint8_t cols[4], grps[4];
164            C93BlockType block_type;
165
166            if (!bt)
167                bt = *buf++;
168
169            block_type= bt & 0x0F;
170            switch (block_type) {
171            case C93_8X8_FROM_PREV:
172                offset = bytestream_get_le16(&buf);
173                if (copy_block(avctx, out, copy_from, offset, 8, stride))
174                    return -1;
175                break;
176
177            case C93_4X4_FROM_CURR:
178                copy_from = newpic->data[0];
179            case C93_4X4_FROM_PREV:
180                for (j = 0; j < 8; j += 4) {
181                    for (i = 0; i < 8; i += 4) {
182                        offset = bytestream_get_le16(&buf);
183                        if (copy_block(avctx, &out[j*stride+i],
184                                           copy_from, offset, 4, stride))
185                            return -1;
186                    }
187                }
188                break;
189
190            case C93_8X8_2COLOR:
191                bytestream_get_buffer(&buf, cols, 2);
192                for (i = 0; i < 8; i++) {
193                    draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
194                                     NULL, *buf++);
195                }
196
197                break;
198
199            case C93_4X4_2COLOR:
200            case C93_4X4_4COLOR:
201            case C93_4X4_4COLOR_GRP:
202                for (j = 0; j < 8; j += 4) {
203                    for (i = 0; i < 8; i += 4) {
204                        if (block_type == C93_4X4_2COLOR) {
205                            bytestream_get_buffer(&buf, cols, 2);
206                            draw_n_color(out + i + j*stride, stride, 4, 4,
207                                    1, cols, NULL, bytestream_get_le16(&buf));
208                        } else if (block_type == C93_4X4_4COLOR) {
209                            bytestream_get_buffer(&buf, cols, 4);
210                            draw_n_color(out + i + j*stride, stride, 4, 4,
211                                    2, cols, NULL, bytestream_get_le32(&buf));
212                        } else {
213                            bytestream_get_buffer(&buf, grps, 4);
214                            draw_n_color(out + i + j*stride, stride, 4, 4,
215                                    1, cols, grps, bytestream_get_le16(&buf));
216                        }
217                    }
218                }
219                break;
220
221            case C93_NOOP:
222                break;
223
224            case C93_8X8_INTRA:
225                for (j = 0; j < 8; j++)
226                    bytestream_get_buffer(&buf, out + j*stride, 8);
227                break;
228
229            default:
230                av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
231                       block_type, x, y);
232                return -1;
233            }
234            bt >>= 4;
235            out += 8;
236        }
237    }
238
239    *picture = *newpic;
240    *data_size = sizeof(AVFrame);
241
242    return buf_size;
243}
244
245AVCodec c93_decoder = {
246    "c93",
247    AVMEDIA_TYPE_VIDEO,
248    CODEC_ID_C93,
249    sizeof(C93DecoderContext),
250    decode_init,
251    NULL,
252    decode_end,
253    decode_frame,
254    CODEC_CAP_DR1,
255    .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
256};
257