1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Coda multi-standard codec IP - MPEG-2 helper functions
4 *
5 * Copyright (C) 2019 Pengutronix, Philipp Zabel
6 */
7
8#include <linux/kernel.h>
9#include <linux/videodev2.h>
10#include "coda.h"
11
12int coda_mpeg2_profile(int profile_idc)
13{
14	switch (profile_idc) {
15	case 5:
16		return V4L2_MPEG_VIDEO_MPEG2_PROFILE_SIMPLE;
17	case 4:
18		return V4L2_MPEG_VIDEO_MPEG2_PROFILE_MAIN;
19	case 3:
20		return V4L2_MPEG_VIDEO_MPEG2_PROFILE_SNR_SCALABLE;
21	case 2:
22		return V4L2_MPEG_VIDEO_MPEG2_PROFILE_SPATIALLY_SCALABLE;
23	case 1:
24		return V4L2_MPEG_VIDEO_MPEG2_PROFILE_HIGH;
25	default:
26		return -EINVAL;
27	}
28}
29
30int coda_mpeg2_level(int level_idc)
31{
32	switch (level_idc) {
33	case 10:
34		return V4L2_MPEG_VIDEO_MPEG2_LEVEL_LOW;
35	case 8:
36		return V4L2_MPEG_VIDEO_MPEG2_LEVEL_MAIN;
37	case 6:
38		return V4L2_MPEG_VIDEO_MPEG2_LEVEL_HIGH_1440;
39	case 4:
40		return V4L2_MPEG_VIDEO_MPEG2_LEVEL_HIGH;
41	default:
42		return -EINVAL;
43	}
44}
45
46/*
47 * Check if the buffer starts with the MPEG-2 sequence header (with or without
48 * quantization matrix) and extension header, for example:
49 *
50 *   00 00 01 b3 2d 01 e0 34 08 8b a3 81
51 *               10 11 11 12 12 12 13 13 13 13 14 14 14 14 14 15
52 *               15 15 15 15 15 16 16 16 16 16 16 16 17 17 17 17
53 *               17 17 17 17 18 18 18 19 18 18 18 19 1a 1a 1a 1a
54 *               19 1b 1b 1b 1b 1b 1c 1c 1c 1c 1e 1e 1e 1f 1f 21
55 *   00 00 01 b5 14 8a 00 01 00 00
56 *
57 * or:
58 *
59 *   00 00 01 b3 08 00 40 15 ff ff e0 28
60 *   00 00 01 b5 14 8a 00 01 00 00
61 *
62 * Returns the detected header size in bytes or 0.
63 */
64u32 coda_mpeg2_parse_headers(struct coda_ctx *ctx, u8 *buf, u32 size)
65{
66	static const u8 sequence_header_start[4] = { 0x00, 0x00, 0x01, 0xb3 };
67	static const union {
68		u8 extension_start[4];
69		u8 start_code_prefix[3];
70	} u = { { 0x00, 0x00, 0x01, 0xb5 } };
71
72	if (size < 22 ||
73	    memcmp(buf, sequence_header_start, 4) != 0)
74		return 0;
75
76	if ((size == 22 ||
77	     (size >= 25 && memcmp(buf + 22, u.start_code_prefix, 3) == 0)) &&
78	    memcmp(buf + 12, u.extension_start, 4) == 0)
79		return 22;
80
81	if ((size == 86 ||
82	     (size > 89 && memcmp(buf + 86, u.start_code_prefix, 3) == 0)) &&
83	    memcmp(buf + 76, u.extension_start, 4) == 0)
84		return 86;
85
86	return 0;
87}
88