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/* SPDX-License-Identifier: GPL-2.0 */
/** \file wma_common.c Functions used by both the WMA afh and decoder. */
#include <sys/types.h>
#include "para.h"
#include "error.h"
#include "afh.h"
#include "portable_io.h"
#include "imdct.h"
#include "wma.h"
/**
* Find the first occurrence of the given pattern.
*
* \param pattern The pattern to search for.
* \param pattern_len The length of the pattern in bytes.
* \param buf The buffer to search for the pattern.
* \param buf_size The number of bytes in \a buf.
*
* \return A pointer into \a buf or \p NULL if the pattern was not found.
*/
const char *search_pattern(const uint8_t *pattern, int pattern_len,
const char *buf, int buf_size)
{
const char *p, *end = buf + buf_size;
/* TODO: Use suffix arrays to speed up the search. */
for (p = buf; p + pattern_len < end; p++) {
if (memcmp(p, pattern, pattern_len))
continue;
PARA_DEBUG_LOG("found %d byte pattern@%d\n",
pattern_len, (int)(p - buf));
return p;
}
PARA_NOTICE_LOG("%d byte pattern not found\n", pattern_len);
return NULL;
}
static int find_file_properties(const char *buf, int len)
{
const uint8_t pattern[] = {0xa1, 0xdc, 0xab, 0x8c};
const char *p = search_pattern(pattern, sizeof(pattern), buf, len);
if (!p)
return -E_WMA_NO_GUID;
PARA_DEBUG_LOG("found file property guid@%0x\n", (unsigned)(p - buf));
return p - buf + 16;
}
/* 40 9e 69 f8 4d 5b cf 11 a8 fd 00 80 5f 5c 44 2b */
static int find_audio_stream_info(const char *buf, int len)
{
const uint8_t pattern[] = {0x40, 0x9e, 0x69, 0xf8};
const char *p = search_pattern(pattern, sizeof(pattern), buf, len);
if (!p)
return -E_WMA_NO_GUID;
PARA_DEBUG_LOG("found audio stream guid@%0x\n", (unsigned)(p - buf));
return p - buf + 16;
}
static int read_header_len(const char *buf, int len)
{
uint16_t header_len;
if (len < 18)
return 0;
header_len = read_u16(buf + 16) + 46;
PARA_DEBUG_LOG("header_len: %d\n", header_len);
return header_len;
}
/**
* Read an asf audio file header.
*
* \param buf The input buffer.
* \param loaded Number of bytes in \a buf.
* \param ahi Result pointer.
*
* \return Negative on errors, zero if more data is needed in order to read the
* full header, 1 on success.
*/
int read_asf_header(const char *buf, int loaded, struct asf_header_info *ahi)
{
int ret;
const char *start;
ahi->header_len = read_header_len(buf, loaded);
if (ahi->header_len == 0) /* too short to read header len */
return 0;
if (ahi->header_len > loaded) /* too short to read header */
return 0;
ret = find_audio_stream_info(buf, ahi->header_len);
if (ret < 0)
return ret;
if (ret + 62 > loaded)
return 0;
ahi->audio_stream_info_start = ret;
start = buf + ahi->audio_stream_info_start;
ahi->channels = ((uint8_t *)start)[40];
ahi->sample_rate = read_u16(start + 42);
PARA_NOTICE_LOG("%d channels, sample rate: %d\n", ahi->channels,
ahi->sample_rate);
ahi->bit_rate = 8 * read_u16(start + 46);
PARA_INFO_LOG("bit rate: %u\n", ahi->bit_rate);
ahi->block_align = read_u16(start + 50);
PARA_INFO_LOG("block_align: %d\n", ahi->block_align);
ahi->flags1 = read_u32(start + 56);
ahi->flags2 = read_u16(start + 60);
PARA_INFO_LOG("read_asf_header: flags1: %u, flags2: %u\n",
ahi->flags1, ahi->flags2);
ahi->use_exp_vlc = ahi->flags2 & 0x0001;
ahi->use_bit_reservoir = ahi->flags2 & 0x0002;
ahi->use_variable_block_len = ahi->flags2 & 0x0004;
ret = find_file_properties(buf, ahi->header_len);
if (ret < 0)
return ret;
/* file property header is always 88 bytes (sans GUID) */
if (ret + 88 > loaded)
return 0;
start = buf + ret;
ahi->packet_size = read_u32(start + 76); /* min packet size */
/* we only support fixed packet sizes */
if (ahi->packet_size != read_u32(start + 80)) /* min != max */
return -E_BAD_ASF_FILE_PROPS;
if (ahi->packet_size <= ahi->block_align)
return -E_BAD_ASF_FILE_PROPS;
PARA_INFO_LOG("packet size: %u\n", ahi->packet_size);
return 1;
}
static const uint8_t log2_tab[256] = {
0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
4, 4, 4, 4, 4, 4, 4, 4,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7
};
/**
* Compute the base-2 logarithm.
*
* \param v The value to compute the logarithm of.
*
* \return An integer approximation of log2(v).
*/
__a_const int wma_log2(unsigned int v)
{
int n = 0;
if (v & 0xffff0000) {
v >>= 16;
n += 16;
}
if (v & 0xff00) {
v >>= 8;
n += 8;
}
return n + log2_tab[v];
}
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