1/*
2 * Westwood SNDx codecs
3 * Copyright (c) 2005 Konstantin Shishkov
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 "libavutil/intreadwrite.h"
23#include "avcodec.h"
24
25/**
26 * @file libavcodec/ws-snd1.c
27 * Westwood SNDx codecs.
28 *
29 * Reference documents about VQA format and its audio codecs
30 * can be found here:
31 * http://www.multimedia.cx
32 */
33
34static const char ws_adpcm_2bit[] = { -2, -1, 0, 1};
35static const char ws_adpcm_4bit[] = {
36    -9, -8, -6, -5, -4, -3, -2, -1,
37     0,  1,  2,  3,  4,  5,  6,  8 };
38
39#define CLIP8(a) if(a>127)a=127;if(a<-128)a=-128;
40
41static av_cold int ws_snd_decode_init(AVCodecContext * avctx)
42{
43//    WSSNDContext *c = avctx->priv_data;
44
45    avctx->sample_fmt = SAMPLE_FMT_S16;
46    return 0;
47}
48
49static int ws_snd_decode_frame(AVCodecContext *avctx,
50                void *data, int *data_size,
51                const uint8_t *buf, int buf_size)
52{
53//    WSSNDContext *c = avctx->priv_data;
54
55    int in_size, out_size;
56    int sample = 0;
57    int i;
58    short *samples = data;
59
60    if (!buf_size)
61        return 0;
62
63    out_size = AV_RL16(&buf[0]);
64    *data_size = out_size * 2;
65    in_size = AV_RL16(&buf[2]);
66    buf += 4;
67
68    if (out_size > *data_size) {
69        av_log(avctx, AV_LOG_ERROR, "Frame is too large to fit in buffer\n");
70        return -1;
71    }
72    if (in_size > buf_size) {
73        av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");
74        return -1;
75    }
76    if (in_size == out_size) {
77        for (i = 0; i < out_size; i++)
78            *samples++ = (*buf++ - 0x80) << 8;
79        return buf_size;
80    }
81
82    while (out_size > 0) {
83        int code;
84        uint8_t count;
85        code = (*buf) >> 6;
86        count = (*buf) & 0x3F;
87        buf++;
88        switch(code) {
89        case 0: /* ADPCM 2-bit */
90            for (count++; count > 0; count--) {
91                code = *buf++;
92                sample += ws_adpcm_2bit[code & 0x3];
93                CLIP8(sample);
94                *samples++ = sample << 8;
95                sample += ws_adpcm_2bit[(code >> 2) & 0x3];
96                CLIP8(sample);
97                *samples++ = sample << 8;
98                sample += ws_adpcm_2bit[(code >> 4) & 0x3];
99                CLIP8(sample);
100                *samples++ = sample << 8;
101                sample += ws_adpcm_2bit[(code >> 6) & 0x3];
102                CLIP8(sample);
103                *samples++ = sample << 8;
104                out_size -= 4;
105            }
106            break;
107        case 1: /* ADPCM 4-bit */
108            for (count++; count > 0; count--) {
109                code = *buf++;
110                sample += ws_adpcm_4bit[code & 0xF];
111                CLIP8(sample);
112                *samples++ = sample << 8;
113                sample += ws_adpcm_4bit[code >> 4];
114                CLIP8(sample);
115                *samples++ = sample << 8;
116                out_size -= 2;
117            }
118            break;
119        case 2: /* no compression */
120            if (count & 0x20) { /* big delta */
121                char t;
122                t = count;
123                t <<= 3;
124                sample += t >> 3;
125                *samples++ = sample << 8;
126                out_size--;
127            } else { /* copy */
128                for (count++; count > 0; count--) {
129                    *samples++ = (*buf++ - 0x80) << 8;
130                    out_size--;
131                }
132                sample = buf[-1] - 0x80;
133            }
134            break;
135        default: /* run */
136            for(count++; count > 0; count--) {
137                *samples++ = sample << 8;
138                out_size--;
139            }
140        }
141    }
142
143    return buf_size;
144}
145
146AVCodec ws_snd1_decoder = {
147    "ws_snd1",
148    CODEC_TYPE_AUDIO,
149    CODEC_ID_WESTWOOD_SND1,
150    0,
151    ws_snd_decode_init,
152    NULL,
153    NULL,
154    ws_snd_decode_frame,
155    .long_name = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"),
156};
157