1/*
2 * XBM parser
3 * Copyright (c) 2021 Paul B Mahol
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/**
23 * @file
24 * XBM parser
25 */
26
27#include "libavutil/common.h"
28
29#include "parser.h"
30
31typedef struct XBMParseContext {
32    ParseContext pc;
33    uint16_t state16;
34    int count;
35} XBMParseContext;
36
37#define KEY (((uint64_t)'\n' << 56) | ((uint64_t)'#' << 48) | \
38             ((uint64_t)'d' << 40)  | ((uint64_t)'e' << 32) | \
39             ((uint64_t)'f' << 24) | ('i' << 16) | ('n' << 8) | \
40             ('e' << 0))
41
42#define END ((';' << 8) | ('\n' << 0))
43
44static int xbm_init(AVCodecParserContext *s)
45{
46    XBMParseContext *bpc = s->priv_data;
47
48    bpc->count = 1;
49
50    return 0;
51}
52
53static int xbm_parse(AVCodecParserContext *s, AVCodecContext *avctx,
54                     const uint8_t **poutbuf, int *poutbuf_size,
55                     const uint8_t *buf, int buf_size)
56{
57    XBMParseContext *bpc = s->priv_data;
58    uint64_t state = bpc->pc.state64;
59    uint16_t state16 = bpc->state16;
60    int next = END_NOT_FOUND, i = 0;
61
62    s->pict_type = AV_PICTURE_TYPE_I;
63    s->key_frame = 1;
64    s->duration  = 1;
65
66    *poutbuf_size = 0;
67    *poutbuf = NULL;
68
69    for (; i < buf_size; i++) {
70        state = (state << 8) | buf[i];
71        state16 = (state16 << 8) | buf[i];
72
73        if (state == KEY)
74            bpc->count++;
75
76        if ((state == KEY && bpc->count == 1)) {
77            next = i - 6;
78            break;
79        } else if (state16 == END) {
80            next = i + 1;
81            bpc->count = 0;
82            break;
83        }
84    }
85
86    bpc->pc.state64 = state;
87    bpc->state16 = state16;
88    if (ff_combine_frame(&bpc->pc, next, &buf, &buf_size) < 0) {
89        *poutbuf = NULL;
90        *poutbuf_size = 0;
91        return buf_size;
92    }
93
94    *poutbuf      = buf;
95    *poutbuf_size = buf_size;
96
97    return next;
98}
99
100const AVCodecParser ff_xbm_parser = {
101    .codec_ids      = { AV_CODEC_ID_XBM },
102    .priv_data_size = sizeof(XBMParseContext),
103    .parser_init    = xbm_init,
104    .parser_parse   = xbm_parse,
105    .parser_close   = ff_parse_close,
106};
107