Added adpcm2lin and lin2adpcm.
diff --git a/Modules/audioop.c b/Modules/audioop.c
index 1dd2da0..c3176f9 100644
--- a/Modules/audioop.c
+++ b/Modules/audioop.c
@@ -130,6 +130,9 @@
}
/* End of code taken from sox */
+/* ADPCM step variation table */
+static float newstep[5] = { 0.8, 0.9, 1.0, 1.75, 1.75 };
+
#define CHARP(cp, i) ((signed char *)(cp+i))
#define SHORTP(cp, i) ((short *)(cp+i))
#define LONGP(cp, i) ((long *)(cp+i))
@@ -546,6 +549,136 @@
return rv;
}
+static object *
+audioop_lin2adpcm(self, args)
+ object *self;
+ object *args;
+{
+ signed char *cp;
+ signed char *ncp;
+ int len, size, val, step, valprev, delta;
+ object *rv, *state, *str;
+ int i;
+
+ if ( !getargs(args, "(s#iO)",
+ &cp, &len, &size, &state) )
+ return 0;
+
+
+ if ( size != 1 && size != 2 && size != 4) {
+ err_setstr(AudioopError, "Size should be 1, 2 or 4");
+ return 0;
+ }
+
+ str = newsizedstringobject(NULL, len/size);
+ if ( str == 0 )
+ return 0;
+ ncp = (signed char *)getstringvalue(str);
+
+ /* Decode state, should have (value, step) */
+ if ( state == None ) {
+ /* First time, it seems. Set defaults */
+ valprev = 0;
+ step = 4; /* The '4' is magic. Dunno it's significance */
+ } else if ( !getargs(state, "(ii)", &valprev, &step) )
+ return 0;
+
+ for ( i=0; i < len; i += size ) {
+ if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 8;
+ else if ( size == 2 ) val = (int)*SHORTP(cp, i);
+ else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 16;
+
+ /* Step 1 - compute difference with previous value */
+ delta = (val - valprev)/step;
+
+ /* Step 2 - Clamp */
+ if ( delta < -4 )
+ delta = -4;
+ else if ( delta > 3 )
+ delta = 3;
+
+ /* Step 3 - Update previous value */
+ valprev += delta*step;
+
+ /* Step 4 - Clamp previous value to 16 bits */
+ if ( valprev > 32767 )
+ valprev = 32767;
+ else if ( valprev < -32768 )
+ valprev = -32768;
+
+ /* Step 5 - Update step value */
+ step = step * newstep[abs(delta)];
+ step++; /* Don't understand this. */
+
+ /* Step 6 - Output value (as a whole byte, currently) */
+ *ncp++ = delta;
+ }
+ rv = mkvalue("(O(ii))", str, valprev, step);
+ DECREF(str);
+ return rv;
+}
+
+static object *
+audioop_adpcm2lin(self, args)
+ object *self;
+ object *args;
+{
+ signed char *cp;
+ signed char *ncp;
+ int len, size, val, valprev, step, delta;
+ object *rv, *str, *state;
+ int i;
+
+ if ( !getargs(args, "(s#iO)",
+ &cp, &len, &size, &state) )
+ return 0;
+
+ if ( size != 1 && size != 2 && size != 4) {
+ err_setstr(AudioopError, "Size should be 1, 2 or 4");
+ return 0;
+ }
+
+ /* Decode state, should have (value, step) */
+ if ( state == None ) {
+ /* First time, it seems. Set defaults */
+ valprev = 0;
+ step = 4; /* The '4' is magic. Dunno it's significance */
+ } else if ( !getargs(state, "(ii)", &valprev, &step) )
+ return 0;
+
+ str = newsizedstringobject(NULL, len*size);
+ if ( str == 0 )
+ return 0;
+ ncp = (signed char *)getstringvalue(str);
+
+ for ( i=0; i < len*size; i += size ) {
+ /* Step 1 - get the delta value */
+ delta = *cp++;
+
+ /* Step 2 - update output value */
+ valprev = valprev + delta*step;
+
+ /* Step 3 - clamp output value */
+ if ( valprev > 32767 )
+ valprev = 32767;
+ else if ( valprev < -32768 )
+ valprev = -32768;
+
+ /* Step 4 - Update step value */
+ step = step * newstep[abs(delta)];
+ step++;
+
+ /* Step 5 - Output value */
+ if ( size == 1 ) *CHARP(ncp, i) = (signed char)(valprev >> 8);
+ else if ( size == 2 ) *SHORTP(ncp, i) = (short)(valprev);
+ else if ( size == 4 ) *LONGP(ncp, i) = (long)(valprev<<16);
+ }
+
+ rv = mkvalue("(O(ii))", str, valprev, step);
+ DECREF(str);
+ return rv;
+}
+
static struct methodlist audioop_methods[] = {
{ "max", audioop_max },
{ "avg", audioop_avg },
@@ -555,6 +688,8 @@
{ "bias", audioop_bias },
{ "ulaw2lin", audioop_ulaw2lin },
{ "lin2ulaw", audioop_lin2ulaw },
+ { "adpcm2lin", audioop_adpcm2lin },
+ { "lin2adpcm", audioop_lin2adpcm },
{ "tomono", audioop_tomono },
{ "tostereo", audioop_tostereo },
{ "getsample", audioop_getsample },