cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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coda-mpeg2.c (2227B)

      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}