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#import <stdio.h>
#import <soundkit/Sound.h>
/* castration of jwp's mixSounds. To multiply a segment of sounds by a scalar */
/* Shorthand macros to handle SNDSoundStructs.
* NSAMPS(s) = number of samples in fragment s
* DATA(s) = Pointer to samples in fragment s
*/
#define NSAMPS(s) (s->dataSize / 2)
#define DATA(s) ((char *)s + s->dataLocation)
#define MIN(a,b) ((a > b) ? b : a)
#define CHANS(s) s->channelCount
int alterSounds(inSound,multiplier,inskip,nsamps)
id inSound; /* Input Sound object */
float multiplier; /* alteration value */
int inskip; /* First sample from input sound */
int nsamps; /* Total number of samples to mix */
{
SNDSoundStruct **inList; /* Pointers to the
* lists of Sound
* fragments*/
SNDSoundStruct *fakein[2]; /* Phoney fragment
* lists for un-
* fragmented Sounds*/
SNDSoundStruct *inStruct; /* Pointers to the
* actual fragments*/
short *in; /* Pointers to data */
int insamps; /* Number of samples in fragments */
int n, blocksize; /* For loop control */
int i = 0;
if ([inSound needsCompacting])
inList = (SNDSoundStruct **)[inSound data];
else {
fakein[0] = [inSound soundStruct];
fakein[1] = NULL;
inList = fakein;
}
inStruct = *inList++;
while (inskip) {
if (NSAMPS(inStruct) > inskip)
break;
inskip -= NSAMPS(inStruct);
if ((inStruct = *inList++) == NULL) {
fprintf(stderr,"mixSounds: inskip too large\n");
return -1;
}
}
in = (short *)DATA(inStruct) + inskip;
insamps = NSAMPS(inStruct) - inskip; /* # of samples left in frag */
i=0;
while (nsamps > 0) {
blocksize = insamps;
for (n = MIN(blocksize,nsamps); n; n--, in++)
*in *= multiplier;
if (!(insamps -= blocksize)) {
if ((inStruct = *inList++) == NULL)
break;
insamps = NSAMPS(inStruct);
in = (short *)DATA(inStruct);
}
nsamps -= blocksize;
}
return 1;
}
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