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#include "alutInternal.h"
ALvoid *
_alutCodecLinear (ALvoid *data, size_t length, ALint numChannels,
ALint bitsPerSample, ALfloat sampleFrequency)
{
return _alutBufferDataConstruct (data, length, numChannels, bitsPerSample,
sampleFrequency);
}
ALvoid *
_alutCodecPCM8s (ALvoid *data, size_t length, ALint numChannels,
ALint bitsPerSample, ALfloat sampleFrequency)
{
int8_t *d = (int8_t *) data;
size_t i;
for (i = 0; i < length; i++)
{
d[i] += (int8_t) 128;
}
return _alutBufferDataConstruct (data, length, numChannels, bitsPerSample,
sampleFrequency);
}
ALvoid *
_alutCodecPCM16 (ALvoid *data, size_t length, ALint numChannels,
ALint bitsPerSample, ALfloat sampleFrequency)
{
int16_t *d = (int16_t *) data;
size_t i, l = length / 2;
for (i = 0; i < l; i++)
{
int16_t x = d[i];
d[i] = ((x << 8) & 0xFF00) | ((x >> 8) & 0x00FF);
}
return _alutBufferDataConstruct (data, length, numChannels, bitsPerSample,
sampleFrequency);
}
/*
* From: http://www.multimedia.cx/simpleaudio.html#tth_sEc6.1
*/
static int16_t
mulaw2linear (uint8_t mulawbyte)
{
static const int16_t exp_lut[8] = {
0, 132, 396, 924, 1980, 4092, 8316, 16764
};
int16_t sign, exponent, mantissa, sample;
mulawbyte = ~mulawbyte;
sign = (mulawbyte & 0x80);
exponent = (mulawbyte >> 4) & 0x07;
mantissa = mulawbyte & 0x0F;
sample = exp_lut[exponent] + (mantissa << (exponent + 3));
if (sign != 0)
{
sample = -sample;
}
return sample;
}
ALvoid *
_alutCodecULaw (ALvoid *data, size_t length, ALint numChannels,
ALint bitsPerSample, ALfloat sampleFrequency)
{
uint8_t *d = (uint8_t *) data;
int16_t *buf = (int16_t *) _alutMalloc (length * 2);
size_t i;
if (buf == NULL)
{
return NULL;
}
for (i = 0; i < length; i++)
{
buf[i] = mulaw2linear (d[i]);
}
free (data);
return _alutBufferDataConstruct (buf, length * 2, numChannels,
bitsPerSample, sampleFrequency);
}
/*
* From: http://www.multimedia.cx/simpleaudio.html#tth_sEc6.1
*/
#define SIGN_BIT (0x80) /* Sign bit for a A-law byte. */
#define QUANT_MASK (0xf) /* Quantization field mask. */
#define SEG_SHIFT (4) /* Left shift for segment number. */
#define SEG_MASK (0x70) /* Segment field mask. */
static int16_t
alaw2linear (uint8_t a_val)
{
int16_t t, seg;
a_val ^= 0x55;
t = (a_val & QUANT_MASK) << 4;
seg = ((int16_t) a_val & SEG_MASK) >> SEG_SHIFT;
switch (seg)
{
case 0:
t += 8;
break;
case 1:
t += 0x108;
break;
default:
t += 0x108;
t <<= seg - 1;
}
return (a_val & SIGN_BIT) ? t : -t;
}
ALvoid *
_alutCodecALaw (ALvoid *data, size_t length, ALint numChannels,
ALint bitsPerSample, ALfloat sampleFrequency)
{
uint8_t *d = (uint8_t *) data;
int16_t *buf = (int16_t *) _alutMalloc (length * 2);
size_t i;
if (buf == NULL)
{
return NULL;
}
for (i = 0; i < length; i++)
{
buf[i] = alaw2linear (d[i]);
}
free (data);
return _alutBufferDataConstruct (buf, length * 2, numChannels,
bitsPerSample, sampleFrequency);
}