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// code from xanim sources...
// (I hope that not hurt copyright :o)
#define xaLONG long
#define xaULONG unsigned long
#define xaBYTE char
#define xaUBYTE unsigned char
//xaULONG long xa_alaw_2_sign[256];
xaULONG xa_alaw_2_sign[256];
xaULONG xa_ulaw_2_sign[256];
/*
** This routine converts from ulaw to 16 bit linear.
**
** Craig Reese: IDA/Supercomputing Research Center
** 29 September 1989
**
** References:
** 1) CCITT Recommendation G.711 (very difficult to follow)
** 2) MIL-STD-188-113,"Interoperability and Performance Standards
** for Analog-to_Digital Conversion Techniques,"
** 17 February 1987
**
** Input: 8 bit ulaw sample
** Output: signed 16 bit linear sample
*/
xaLONG XA_uLaw_to_Signed( ulawbyte )
xaUBYTE ulawbyte;
{
static int exp_lut[8] = { 0, 132, 396, 924, 1980, 4092, 8316, 16764 };
int sign, exponent, mantissa, sample;
ulawbyte = ~ ulawbyte;
sign = ( ulawbyte & 0x80 );
exponent = ( ulawbyte >> 4 ) & 0x07;
mantissa = ulawbyte & 0x0F;
sample = exp_lut[exponent] + ( mantissa << ( exponent + 3 ) );
if ( sign != 0 ) sample = -sample;
return sample;
}
void Gen_uLaw_2_Signed()
{ xaULONG i;
for(i=0;i<256;i++)
{ xaUBYTE data = (xaUBYTE)(i);
xaLONG d = XA_uLaw_to_Signed( data );
xa_ulaw_2_sign[i] = (xaULONG)((xaULONG)(d) & 0xffff);
}
}
void Gen_aLaw_2_Signed()
{ xaULONG i;
for(i=0;i<256;i++)
{ xaUBYTE data = (xaUBYTE)(i);
xaLONG d, t, seg;
data ^= 0x55;
t = (data & 0xf) << 4;
seg = (data & 0x70) >> 4;
if (seg == 0) t += 8;
else if (seg == 1) t += 0x108;
else { t += 108; t <<= seg - 1; }
d = (data & 0x80)?(t):(-t);
xa_alaw_2_sign[i] = (xaULONG)((xaULONG)(d) & 0xffff);
}
}
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