#include <glib.h>
-#define ZEROTRAP /* turn on the trap as per the MIL-STD */
-#define BIAS 0x84 /* define the add-in bias for 16 bit samples */
+#include "mulaw-conversion.h"
+
+#undef ZEROTRAP /* turn on the trap as per the MIL-STD */
+#define BIAS 0x84 /* define the add-in bias for 16 bit samples */
#define CLIP 32635
void
-mulaw_encode(gint16* in, guint8* out, gint numsamples)
+mulaw_encode (gint16 * in, guint8 * out, gint numsamples)
{
- static gint16 exp_lut[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};
- gint16 sign, exponent, mantissa,i;
- gint16 sample;
- guint8 ulawbyte;
+ static const gint16 exp_lut[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
+ };
+ gint16 sign, exponent, mantissa;
+ gint16 sample;
+ guint8 ulawbyte;
+ gint i;
- for(i=0;i<numsamples;i++) {
- sample=in[i];
+ for (i = 0; i < numsamples; i++) {
+ sample = in[i];
/** get the sample into sign-magnitude **/
- sign = (sample >> 8) & 0x80; /* set aside the sign */
- if (sign != 0) sample = -sample; /* get magnitude */
- if (sample > CLIP) sample = CLIP; /* clip the magnitude */
+ sign = (sample >> 8) & 0x80; /* set aside the sign */
+ if (sign != 0) {
+ sample = -sample; /* get magnitude */
+ }
+ /* sample can be zero because we can overflow in the inversion,
+ * checking against the unsigned version solves this */
+ if (((guint16) sample) > CLIP)
+ sample = CLIP; /* clip the magnitude */
+
/** convert from 16 bit linear to ulaw **/
- sample = sample + BIAS;
- exponent = exp_lut[(sample>>7) & 0xFF];
- mantissa = (sample >> (exponent+3)) & 0x0F;
- ulawbyte = ~(sign | (exponent << 4) | mantissa);
+ sample = sample + BIAS;
+ exponent = exp_lut[(sample >> 7) & 0xFF];
+ mantissa = (sample >> (exponent + 3)) & 0x0F;
+ ulawbyte = ~(sign | (exponent << 4) | mantissa);
#ifdef ZEROTRAP
- if (ulawbyte == 0 ) ulawbyte = 0x02; /* optional CCITT trap */
+ if (ulawbyte == 0)
+ ulawbyte = 0x02; /* optional CCITT trap */
#endif
- out[i]=ulawbyte;
- }
+ out[i] = ulawbyte;
+ }
}
/*
*/
void
-mulaw_decode(guint8* in,gint16* out,gint numsamples)
+mulaw_decode (guint8 * in, gint16 * out, gint numsamples)
{
- static gint16 exp_lut[8]={0,132,396,924,1980,4092,8316,16764};
- gint16 sign, exponent, mantissa;
- guint8 ulawbyte;
- gint16 linear,i;
- for(i=0;i<numsamples;i++) {
- ulawbyte=in[i];
- ulawbyte = ~ulawbyte;
- sign = (ulawbyte & 0x80);
- exponent = (ulawbyte >> 4) & 0x07;
- mantissa = ulawbyte & 0x0F;
- linear = exp_lut[exponent] + (mantissa << (exponent+3));
- if (sign != 0) linear = -linear;
- out[i]=linear;
- }
+ static const gint16 exp_lut[8] =
+ { 0, 132, 396, 924, 1980, 4092, 8316, 16764 };
+ gint16 sign, exponent, mantissa;
+ guint8 ulawbyte;
+ gint16 linear;
+ gint i;
+
+ for (i = 0; i < numsamples; i++) {
+ ulawbyte = in[i];
+ ulawbyte = ~ulawbyte;
+ sign = (ulawbyte & 0x80);
+ exponent = (ulawbyte >> 4) & 0x07;
+ mantissa = ulawbyte & 0x0F;
+ linear = exp_lut[exponent] + (mantissa << (exponent + 3));
+ if (sign != 0)
+ linear = -linear;
+ out[i] = linear;
+ }
}