ref: 2908e46d3f2505e8d13845aecddde2d78833068f
dir: /src/trim.c/
/*
* July 5, 1991
* Copyright 1991 Lance Norskog And Sundry Contributors
* This source code is freely redistributable and may be used for
* any purpose. This copyright notice must be maintained.
* Lance Norskog And Sundry Contributors are not responsible for
* the consequences of using this software.
*/
/*
* Sound Tools skeleton effect file.
*/
#include "st.h"
#include <string.h>
/* Time resolutin one millisecond */
#define TIMERES 1000
#define TRIM_USAGE "Trim usage: trim start [length]"
typedef struct
{
/* options here */
LONG start;
LONG length;
/* internal stuff */
LONG index;
LONG trimmed;
int done;
} * trim_t;
/*
* Process options
*/
int st_trim_getopts(effp, n, argv)
eff_t effp;
int n;
char **argv;
{
trim_t trim = (trim_t) effp->priv;
double time;
trim->start = 0;
trim->length = 0;
switch (n) {
case 2:
time = st_parsetime(argv[1]);
if (time >= 0.0)
{
trim->length = time * TIMERES;
}
else
{
st_fail(TRIM_USAGE);
return(ST_EOF);
}
case 1:
time = st_parsetime(argv[0]);
if (time >= 0.0)
{
trim->start = time * TIMERES;
}
else
{
st_fail(TRIM_USAGE);
return(ST_EOF);
}
break;
default:
st_fail(TRIM_USAGE);
return ST_EOF;
break;
}
return (ST_SUCCESS);
}
/*
* Start processing
*/
int st_trim_start(effp)
eff_t effp;
{
trim_t trim = (trim_t) effp->priv;
trim->start = (double)effp->ininfo.channels * effp->ininfo.rate * trim->start / TIMERES;
if (trim->start < 0)
{
st_fail("trim: start must be positive");
}
trim->length = (double)effp->ininfo.channels * effp->ininfo.rate * trim->length / TIMERES;
if (trim->length < 0)
{
st_fail("trim: length must be positive");
}
trim->done = 0;
trim->index = 0;
trim->trimmed = 0;
return (ST_SUCCESS);
}
/*
* Read up to len samples from file.
* Convert to signed longs.
* Place in buf[].
* Return number of samples read.
*/
int st_trim_flow(effp, ibuf, obuf, isamp, osamp)
eff_t effp;
LONG *ibuf, *obuf;
LONG *isamp, *osamp;
{
int done;
int offset;
int start_trim = 0;
trim_t trim = (trim_t) effp->priv;
done = ((*isamp < *osamp) ? *isamp : *osamp);
*isamp = done; /* always read this much */
if (trim->done) {
*osamp = 0;
return (ST_EOF);
}
trim->index += done;
offset = 0;
if (! trim->trimmed) {
if (trim->start > trim->index) {
*osamp = 0;
return (ST_SUCCESS);
} else {
start_trim = 1;
offset = (trim->start==0? 0: trim->index - trim->start);
done -= offset; /* adjust done */
}
}
if (trim->trimmed || start_trim ) {
if (trim->length && ( (trim->trimmed+done) > trim->length)) {
done = trim->length - trim->trimmed ;
*osamp = done;
trim->done = 1;
}
trim->trimmed += done;
}
memcpy(obuf, ibuf+offset, done * sizeof(LONG));
*osamp = done;
return (ST_SUCCESS);
}
/*
* Do anything required when you stop reading samples.
* Don't close input file!
*/
int st_trim_stop(effp)
eff_t effp;
{
/* nothing to do */
return (ST_SUCCESS);
}