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, const uint8_t * buf, int buf_size)
117{
118    C93DecoderContext * const c93 = avctx->priv_data;
119    AVFrame * const newpic = &c93->pictures[c93->currentpic];
120    AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
121    AVFrame *picture = data;
122    uint8_t *out;
123    int stride, i, x, y, bt = 0;
124
125    c93->currentpic ^= 1;
126
127    newpic->reference = 1;
128    newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
129                         FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
130    if (avctx->reget_buffer(avctx, newpic)) {
131        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
132        return -1;
133    }
134
135    stride = newpic->linesize[0];
136
137    if (buf[0] & C93_FIRST_FRAME) {
138        newpic->pict_type = FF_I_TYPE;
139        newpic->key_frame = 1;
140    } else {
141        newpic->pict_type = FF_P_TYPE;
142        newpic->key_frame = 0;
143    }
144
145    if (*buf++ & C93_HAS_PALETTE) {
146        uint32_t *palette = (uint32_t *) newpic->data[1];
147        const uint8_t *palbuf = buf + buf_size - 768 - 1;
148        for (i = 0; i < 256; i++) {
149            palette[i] = bytestream_get_be24(&palbuf);
150        }
151    } else {
152        if (oldpic->data[1])
153            memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
154    }
155
156    for (y = 0; y < HEIGHT; y += 8) {
157        out = newpic->data[0] + y * stride;
158        for (x = 0; x < WIDTH; x += 8) {
159            uint8_t *copy_from = oldpic->data[0];
160            unsigned int offset, j;
161            uint8_t cols[4], grps[4];
162            C93BlockType block_type;
163
164            if (!bt)
165                bt = *buf++;
166
167            block_type= bt & 0x0F;
168            switch (block_type) {
169            case C93_8X8_FROM_PREV:
170                offset = bytestream_get_le16(&buf);
171                if (copy_block(avctx, out, copy_from, offset, 8, stride))
172                    return -1;
173                break;
174
175            case C93_4X4_FROM_CURR:
176                copy_from = newpic->data[0];
177            case C93_4X4_FROM_PREV:
178                for (j = 0; j < 8; j += 4) {
179                    for (i = 0; i < 8; i += 4) {
180                        offset = bytestream_get_le16(&buf);
181                        if (copy_block(avctx, &out[j*stride+i],
182                                           copy_from, offset, 4, stride))
183                            return -1;
184                    }
185                }
186                break;
187
188            case C93_8X8_2COLOR:
189                bytestream_get_buffer(&buf, cols, 2);
190                for (i = 0; i < 8; i++) {
191                    draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
192                                     NULL, *buf++);
193                }
194
195                break;
196
197            case C93_4X4_2COLOR:
198            case C93_4X4_4COLOR:
199            case C93_4X4_4COLOR_GRP:
200                for (j = 0; j < 8; j += 4) {
201                    for (i = 0; i < 8; i += 4) {
202                        if (block_type == C93_4X4_2COLOR) {
203                            bytestream_get_buffer(&buf, cols, 2);
204                            draw_n_color(out + i + j*stride, stride, 4, 4,
205                                    1, cols, NULL, bytestream_get_le16(&buf));
206                        } else if (block_type == C93_4X4_4COLOR) {
207                            bytestream_get_buffer(&buf, cols, 4);
208                            draw_n_color(out + i + j*stride, stride, 4, 4,
209                                    2, cols, NULL, bytestream_get_le32(&buf));
210                        } else {
211                            bytestream_get_buffer(&buf, grps, 4);
212                            draw_n_color(out + i + j*stride, stride, 4, 4,
213                                    1, cols, grps, bytestream_get_le16(&buf));
214                        }
215                    }
216                }
217                break;
218
219            case C93_NOOP:
220                break;
221
222            case C93_8X8_INTRA:
223                for (j = 0; j < 8; j++)
224                    bytestream_get_buffer(&buf, out + j*stride, 8);
225                break;
226
227            default:
228                av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
229                       block_type, x, y);
230                return -1;
231            }
232            bt >>= 4;
233            out += 8;
234        }
235    }
236
237    *picture = *newpic;
238    *data_size = sizeof(AVFrame);
239
240    return buf_size;
241}
242
243AVCodec c93_decoder = {
244    "c93",
245    CODEC_TYPE_VIDEO,
246    CODEC_ID_C93,
247    sizeof(C93DecoderContext),
248    decode_init,
249    NULL,
250    decode_end,
251    decode_frame,
252    CODEC_CAP_DR1,
253    .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
254};
255