factorize & 0x0F
[libav.git] / libavcodec / c93.c
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,
20 * MA 02110-1301 USA
21 */
22
23 #include "avcodec.h"
24 #include "bytestream.h"
25
26 typedef struct {
27 AVFrame pictures[2];
28 int currentpic;
29 } C93DecoderContext;
30
31 typedef enum {
32 C93_8X8_FROM_PREV = 0x02,
33 C93_4X4_FROM_PREV = 0x06,
34 C93_4X4_FROM_CURR = 0x07,
35 C93_8X8_2COLOR = 0x08,
36 C93_4X4_2COLOR = 0x0A,
37 C93_4X4_4COLOR_GRP = 0x0B,
38 C93_4X4_4COLOR = 0x0D,
39 C93_NOOP = 0x0E,
40 C93_8X8_INTRA = 0x0F,
41 } C93BlockType;
42
43 #define WIDTH 320
44 #define HEIGHT 192
45
46 #define C93_HAS_PALETTE 0x01
47 #define C93_FIRST_FRAME 0x02
48
49 static int decode_init(AVCodecContext *avctx)
50 {
51 avctx->pix_fmt = PIX_FMT_PAL8;
52 return 0;
53 }
54
55 static int decode_end(AVCodecContext *avctx)
56 {
57 C93DecoderContext * const c93 = avctx->priv_data;
58
59 if (c93->pictures[0].data[0])
60 avctx->release_buffer(avctx, &c93->pictures[0]);
61 if (c93->pictures[1].data[0])
62 avctx->release_buffer(avctx, &c93->pictures[1]);
63 return 0;
64 }
65
66 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
67 uint8_t *from, int offset, int height, int stride)
68 {
69 int i;
70 int width = height;
71 int from_x = offset % WIDTH;
72 int from_y = offset / WIDTH;
73 int overflow = from_x + width - WIDTH;
74
75 if (!from) {
76 /* silently ignoring predictive blocks in first frame */
77 return 0;
78 }
79
80 if (from_y + height > HEIGHT) {
81 av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
82 offset);
83 return -1;
84 }
85
86 if (overflow > 0) {
87 width -= overflow;
88 for (i = 0; i < height; i++) {
89 memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
90 }
91 }
92
93 for (i = 0; i < height; i++) {
94 memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
95 }
96
97 return 0;
98 }
99
100 static inline void draw_n_color(uint8_t *out, int stride, int width,
101 int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
102 {
103 int x, y;
104 for (y = 0; y < height; y++) {
105 if (grps)
106 cols[0] = grps[3 * (y >> 1)];
107 for (x = 0; x < width; x++) {
108 if (grps)
109 cols[1]= grps[(x >> 1) + 1];
110 out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
111 col >>= bpp;
112 }
113 }
114 }
115
116 static int decode_frame(AVCodecContext *avctx, void *data,
117 int *data_size, uint8_t * buf, int buf_size)
118 {
119 C93DecoderContext * const c93 = avctx->priv_data;
120 AVFrame * const newpic = &c93->pictures[c93->currentpic];
121 AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
122 AVFrame *picture = data;
123 uint8_t *out;
124 int stride, i, x, y, bt = 0;
125
126 c93->currentpic ^= 1;
127
128 newpic->reference = 1;
129 newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
130 FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
131 if (avctx->reget_buffer(avctx, newpic)) {
132 av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
133 return -1;
134 }
135
136 stride = newpic->linesize[0];
137
138 if (buf[0] & C93_FIRST_FRAME) {
139 newpic->pict_type = FF_I_TYPE;
140 newpic->key_frame = 1;
141 } else {
142 newpic->pict_type = FF_P_TYPE;
143 newpic->key_frame = 0;
144 }
145
146 if (*buf++ & C93_HAS_PALETTE) {
147 uint32_t *palette = (uint32_t *) newpic->data[1];
148 uint8_t *palbuf = buf + buf_size - 768 - 1;
149 for (i = 0; i < 256; i++) {
150 palette[i] = bytestream_get_be24(&palbuf);
151 }
152 } else {
153 if (oldpic->data[1])
154 memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
155 }
156
157 for (y = 0; y < HEIGHT; y += 8) {
158 out = newpic->data[0] + y * stride;
159 for (x = 0; x < WIDTH; x += 8) {
160 uint8_t *copy_from = oldpic->data[0];
161 unsigned int offset, j;
162 uint8_t cols[4], grps[4];
163 C93BlockType block_type;
164
165 if (!bt)
166 bt = *buf++;
167
168 block_type= bt & 0x0F;
169 switch (block_type) {
170 case C93_8X8_FROM_PREV:
171 offset = bytestream_get_le16(&buf);
172 if (copy_block(avctx, out, copy_from, offset, 8, stride))
173 return -1;
174 break;
175
176 case C93_4X4_FROM_CURR:
177 copy_from = newpic->data[0];
178 case C93_4X4_FROM_PREV:
179 for (j = 0; j < 8; j += 4) {
180 for (i = 0; i < 8; i += 4) {
181 offset = bytestream_get_le16(&buf);
182 if (copy_block(avctx, &out[j*stride+i],
183 copy_from, offset, 4, stride))
184 return -1;
185 }
186 }
187 break;
188
189 case C93_8X8_2COLOR:
190 bytestream_get_buffer(&buf, cols, 2);
191 for (i = 0; i < 8; i++) {
192 draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
193 NULL, *buf++);
194 }
195
196 break;
197
198 case C93_4X4_2COLOR:
199 case C93_4X4_4COLOR:
200 case C93_4X4_4COLOR_GRP:
201 for (j = 0; j < 8; j += 4) {
202 for (i = 0; i < 8; i += 4) {
203 if (block_type == C93_4X4_2COLOR) {
204 bytestream_get_buffer(&buf, cols, 2);
205 draw_n_color(out + i + j*stride, stride, 4, 4,
206 1, cols, NULL, bytestream_get_le16(&buf));
207 } else if (block_type == C93_4X4_4COLOR) {
208 bytestream_get_buffer(&buf, cols, 4);
209 draw_n_color(out + i + j*stride, stride, 4, 4,
210 2, cols, NULL, bytestream_get_le32(&buf));
211 } else {
212 bytestream_get_buffer(&buf, grps, 4);
213 draw_n_color(out + i + j*stride, stride, 4, 4,
214 1, cols, grps, bytestream_get_le16(&buf));
215 }
216 }
217 }
218 break;
219
220 case C93_NOOP:
221 break;
222
223 case C93_8X8_INTRA:
224 for (j = 0; j < 8; j++)
225 bytestream_get_buffer(&buf, out + j*stride, 8);
226 break;
227
228 default:
229 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
230 block_type, x, y);
231 return -1;
232 }
233 bt >>= 4;
234 out += 8;
235 }
236 }
237
238 *picture = *newpic;
239 *data_size = sizeof(AVFrame);
240
241 return buf_size;
242 }
243
244 AVCodec c93_decoder = {
245 "c93",
246 CODEC_TYPE_VIDEO,
247 CODEC_ID_C93,
248 sizeof(C93DecoderContext),
249 decode_init,
250 NULL,
251 decode_end,
252 decode_frame,
253 CODEC_CAP_DR1,
254 };