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mkxp-z/SDL2_sound/SDL_sound_au.c

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/**
* SDL_sound; An abstract sound format decoding API.
*
* Please see the file LICENSE.txt in the source's root directory.
*
* This file written by Mattias Engdegård.
*/
/*
* Sun/NeXT .au decoder for SDL_sound.
* Formats supported: 8 and 16 bit linear PCM, 8 bit µ-law.
* Files without valid header are assumed to be 8 bit µ-law, 8kHz, mono.
*/
#define __SDL_SOUND_INTERNAL__
#include "SDL_sound_internal.h"
#if SOUND_SUPPORTS_AU
/* no init/deinit needed */
static int AU_init(void)
{
return 1;
} /* AU_init */
static void AU_quit(void)
{
/* no-op. */
} /* AU_quit */
struct au_file_hdr
{
Uint32 magic;
Uint32 hdr_size;
Uint32 data_size;
Uint32 encoding;
Uint32 sample_rate;
Uint32 channels;
};
#define HDR_SIZE 24
enum
{
AU_ENC_ULAW_8 = 1, /* 8-bit ISDN µ-law */
AU_ENC_LINEAR_8 = 2, /* 8-bit linear PCM */
AU_ENC_LINEAR_16 = 3, /* 16-bit linear PCM */
/* the rest are unsupported (I have never seen them in the wild) */
AU_ENC_LINEAR_24 = 4, /* 24-bit linear PCM */
AU_ENC_LINEAR_32 = 5, /* 32-bit linear PCM */
AU_ENC_FLOAT = 6, /* 32-bit IEEE floating point */
AU_ENC_DOUBLE = 7, /* 64-bit IEEE floating point */
/* more Sun formats, not supported either */
AU_ENC_ADPCM_G721 = 23,
AU_ENC_ADPCM_G722 = 24,
AU_ENC_ADPCM_G723_3 = 25,
AU_ENC_ADPCM_G723_5 = 26,
AU_ENC_ALAW_8 = 27
};
struct audec
{
Uint32 total;
Uint32 remaining;
Uint32 start_offset;
int encoding;
};
/*
* Read in the AU header from disk. This makes this process safe
* regardless of the processor's byte order or how the au_file_hdr
* structure is packed.
*/
static int read_au_header(SDL_RWops *rw, struct au_file_hdr *hdr)
{
if (SDL_RWread(rw, &hdr->magic, sizeof (hdr->magic), 1) != 1)
return 0;
hdr->magic = SDL_SwapBE32(hdr->magic);
if (SDL_RWread(rw, &hdr->hdr_size, sizeof (hdr->hdr_size), 1) != 1)
return 0;
hdr->hdr_size = SDL_SwapBE32(hdr->hdr_size);
if (SDL_RWread(rw, &hdr->data_size, sizeof (hdr->data_size), 1) != 1)
return 0;
hdr->data_size = SDL_SwapBE32(hdr->data_size);
if (SDL_RWread(rw, &hdr->encoding, sizeof (hdr->encoding), 1) != 1)
return 0;
hdr->encoding = SDL_SwapBE32(hdr->encoding);
if (SDL_RWread(rw, &hdr->sample_rate, sizeof (hdr->sample_rate), 1) != 1)
return 0;
hdr->sample_rate = SDL_SwapBE32(hdr->sample_rate);
if (SDL_RWread(rw, &hdr->channels, sizeof (hdr->channels), 1) != 1)
return 0;
hdr->channels = SDL_SwapBE32(hdr->channels);
return 1;
} /* read_au_header */
#define AU_MAGIC 0x2E736E64 /* ".snd", in ASCII (bigendian number) */
static int AU_open(Sound_Sample *sample, const char *ext)
{
Sound_SampleInternal *internal = sample->opaque;
SDL_RWops *rw = internal->rw;
int skip, hsize, i, bytes_per_second;
struct au_file_hdr hdr;
struct audec *dec;
char c;
/* read_au_header() will do byte order swapping. */
BAIL_IF_MACRO(!read_au_header(rw, &hdr), "AU: bad header", 0);
dec = SDL_malloc(sizeof *dec);
BAIL_IF_MACRO(dec == NULL, ERR_OUT_OF_MEMORY, 0);
internal->decoder_private = dec;
if (hdr.magic == AU_MAGIC)
{
/* valid magic */
dec->encoding = hdr.encoding;
switch(dec->encoding)
{
case AU_ENC_ULAW_8:
/* Convert 8-bit µ-law to 16-bit linear on the fly. This is
slightly wasteful if the audio driver must convert them
back, but µ-law only devices are rare (mostly _old_ Suns) */
sample->actual.format = AUDIO_S16SYS;
break;
case AU_ENC_LINEAR_8:
sample->actual.format = AUDIO_S8;
break;
case AU_ENC_LINEAR_16:
sample->actual.format = AUDIO_S16MSB;
break;
default:
SDL_free(dec);
BAIL_MACRO("AU: Unsupported .au encoding", 0);
} /* switch */
sample->actual.rate = hdr.sample_rate;
sample->actual.channels = hdr.channels;
dec->remaining = hdr.data_size;
hsize = hdr.hdr_size;
/* skip remaining part of header (input may be unseekable) */
for (i = HDR_SIZE; i < hsize; i++)
{
if (SDL_RWread(rw, &c, 1, 1) != 1)
{
SDL_free(dec);
BAIL_MACRO(ERR_IO_ERROR, 0);
} /* if */
} /* for */
} /* if */
else if (SDL_strcasecmp(ext, "au") == 0)
{
/*
* A number of files in the wild have the .au extension but no valid
* header; these are traditionally assumed to be 8kHz µ-law. Handle
* them here only if the extension is recognized.
*/
SNDDBG(("AU: Invalid header, assuming raw 8kHz µ-law.\n"));
/* if seeking fails, we lose 24 samples. big deal */
SDL_RWseek(rw, -HDR_SIZE, SEEK_CUR);
dec->encoding = AU_ENC_ULAW_8;
dec->remaining = (Uint32)-1; /* no limit */
sample->actual.format = AUDIO_S16SYS;
sample->actual.rate = 8000;
sample->actual.channels = 1;
} /* else if */
else
{
SDL_free(dec);
BAIL_MACRO("AU: Not an .AU stream.", 0);
} /* else */
bytes_per_second = ( ( dec->encoding == AU_ENC_LINEAR_16 ) ? 2 : 1 )
* sample->actual.rate * sample->actual.channels ;
internal->total_time = ((dec->remaining == -1) ? (-1) :
( ( dec->remaining / bytes_per_second ) * 1000 ) +
( ( dec->remaining % bytes_per_second ) * 1000 /
bytes_per_second ) );
sample->flags = SOUND_SAMPLEFLAG_CANSEEK;
dec->total = dec->remaining;
dec->start_offset = SDL_RWtell(rw);
SNDDBG(("AU: Accepting data stream.\n"));
return 1;
} /* AU_open */
static void AU_close(Sound_Sample *sample)
{
Sound_SampleInternal *internal = sample->opaque;
SDL_free(internal->decoder_private);
} /* AU_close */
/* table to convert from µ-law encoding to signed 16-bit samples,
generated by a throwaway perl script */
static Sint16 ulaw_to_linear[256] = {
-32124,-31100,-30076,-29052,-28028,-27004,-25980,-24956,
-23932,-22908,-21884,-20860,-19836,-18812,-17788,-16764,
-15996,-15484,-14972,-14460,-13948,-13436,-12924,-12412,
-11900,-11388,-10876,-10364, -9852, -9340, -8828, -8316,
-7932, -7676, -7420, -7164, -6908, -6652, -6396, -6140,
-5884, -5628, -5372, -5116, -4860, -4604, -4348, -4092,
-3900, -3772, -3644, -3516, -3388, -3260, -3132, -3004,
-2876, -2748, -2620, -2492, -2364, -2236, -2108, -1980,
-1884, -1820, -1756, -1692, -1628, -1564, -1500, -1436,
-1372, -1308, -1244, -1180, -1116, -1052, -988, -924,
-876, -844, -812, -780, -748, -716, -684, -652,
-620, -588, -556, -524, -492, -460, -428, -396,
-372, -356, -340, -324, -308, -292, -276, -260,
-244, -228, -212, -196, -180, -164, -148, -132,
-120, -112, -104, -96, -88, -80, -72, -64,
-56, -48, -40, -32, -24, -16, -8, 0,
32124, 31100, 30076, 29052, 28028, 27004, 25980, 24956,
23932, 22908, 21884, 20860, 19836, 18812, 17788, 16764,
15996, 15484, 14972, 14460, 13948, 13436, 12924, 12412,
11900, 11388, 10876, 10364, 9852, 9340, 8828, 8316,
7932, 7676, 7420, 7164, 6908, 6652, 6396, 6140,
5884, 5628, 5372, 5116, 4860, 4604, 4348, 4092,
3900, 3772, 3644, 3516, 3388, 3260, 3132, 3004,
2876, 2748, 2620, 2492, 2364, 2236, 2108, 1980,
1884, 1820, 1756, 1692, 1628, 1564, 1500, 1436,
1372, 1308, 1244, 1180, 1116, 1052, 988, 924,
876, 844, 812, 780, 748, 716, 684, 652,
620, 588, 556, 524, 492, 460, 428, 396,
372, 356, 340, 324, 308, 292, 276, 260,
244, 228, 212, 196, 180, 164, 148, 132,
120, 112, 104, 96, 88, 80, 72, 64,
56, 48, 40, 32, 24, 16, 8, 0
};
static Uint32 AU_read(Sound_Sample *sample)
{
int ret;
Sound_SampleInternal *internal = sample->opaque;
struct audec *dec = internal->decoder_private;
int maxlen;
Uint8 *buf;
maxlen = internal->buffer_size;
buf = internal->buffer;
if (dec->encoding == AU_ENC_ULAW_8)
{
/* We read µ-law samples into the second half of the buffer, so
we can expand them to 16-bit samples afterwards */
maxlen >>= 1;
buf += maxlen;
} /* if */
if (maxlen > dec->remaining)
maxlen = dec->remaining;
ret = SDL_RWread(internal->rw, buf, 1, maxlen);
if (ret == 0)
sample->flags |= SOUND_SAMPLEFLAG_EOF;
else if (ret == -1)
sample->flags |= SOUND_SAMPLEFLAG_ERROR;
else
{
dec->remaining -= ret;
if (ret < maxlen)
sample->flags |= SOUND_SAMPLEFLAG_EAGAIN;
if (dec->encoding == AU_ENC_ULAW_8)
{
int i;
Sint16 *dst = internal->buffer;
for (i = 0; i < ret; i++)
dst[i] = ulaw_to_linear[buf[i]];
ret <<= 1; /* return twice as much as read */
} /* if */
} /* else */
return ret;
} /* AU_read */
static int AU_rewind(Sound_Sample *sample)
{
Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
struct audec *dec = (struct audec *) internal->decoder_private;
int rc = SDL_RWseek(internal->rw, dec->start_offset, SEEK_SET);
BAIL_IF_MACRO(rc != dec->start_offset, ERR_IO_ERROR, 0);
dec->remaining = dec->total;
return 1;
} /* AU_rewind */
static int AU_seek(Sound_Sample *sample, Uint32 ms)
{
Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
struct audec *dec = (struct audec *) internal->decoder_private;
int offset = __Sound_convertMsToBytePos(&sample->actual, ms);
int rc;
int pos;
if (dec->encoding == AU_ENC_ULAW_8)
offset >>= 1; /* halve the byte offset for compression. */
pos = (int) (dec->start_offset + offset);
rc = SDL_RWseek(internal->rw, pos, SEEK_SET);
BAIL_IF_MACRO(rc != pos, ERR_IO_ERROR, 0);
dec->remaining = dec->total - offset;
return 1;
} /* AU_seek */
/*
* Sometimes the extension ".snd" is used for these files (mostly on the NeXT),
* and the magic number comes from this. However it may clash with other
* formats and is somewhat of an anachronism, so only .au is used here.
*/
static const char *extensions_au[] = { "AU", NULL };
const Sound_DecoderFunctions __Sound_DecoderFunctions_AU =
{
{
extensions_au,
"Sun/NeXT audio file format",
"Mattias Engdegård <f91-men@nada.kth.se>",
"https://icculus.org/SDL_sound/"
},
AU_init, /* init() method */
AU_quit, /* quit() method */
AU_open, /* open() method */
AU_close, /* close() method */
AU_read, /* read() method */
AU_rewind, /* rewind() method */
AU_seek /* seek() method */
};
#endif /* SOUND_SUPPORTS_AU */
/* end of SDL_sound_au.c ... */
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