ref: b91c9d5d7ce73a1b90794fa008fc2dc4cde53886
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 */
char *start_str;
char *length_str;
/* options converted to values */
ULONG start;
ULONG length;
/* internal stuff */
ULONG index;
ULONG 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;
/* Do not know sample rate yet so hold off on completely parsing
* time related strings.
*/
switch (n) {
case 2:
trim->length_str = malloc(strlen(argv[1])+1);
if (!trim->length_str)
{
st_fail("Could not allocate memory");
return(ST_EOF);
}
strcpy(trim->length_str,argv[1]);
/* Do a dummy parse to see if it will fail */
if (st_parsesamples(0, trim->length_str,
&trim->length, 't') != ST_SUCCESS)
{
st_fail(TRIM_USAGE);
return(ST_EOF);
}
case 1:
trim->start_str = malloc(strlen(argv[0])+1);
if (!trim->start_str)
{
st_fail("Could not allocate memory");
return(ST_EOF);
}
strcpy(trim->start_str,argv[0]);
/* Do a dummy parse to see if it will fail */
if (st_parsesamples(0, trim->start_str,
&trim->start, 't') != ST_SUCCESS)
{
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;
if (st_parsesamples(effp->ininfo.rate, trim->start_str,
&trim->start, 't') != ST_SUCCESS)
{
st_fail(TRIM_USAGE);
return(ST_EOF);
}
/* Account for # of channels */
trim->start *= effp->ininfo.channels;
if (trim->length_str)
{
if (st_parsesamples(effp->ininfo.rate, trim->length_str,
&trim->length, 't') != ST_SUCCESS)
{
st_fail(TRIM_USAGE);
return(ST_EOF);
}
}
else
trim->length = 0;
/* Account for # of channels */
trim->length *= effp->ininfo.channels;
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;
/* Compute the most samples we can process this time */
done = ((*isamp < *osamp) ? *isamp : *osamp);
/* Always report that we've read everything for default case */
*isamp = done;
/* Don't bother doing work if we are done */
if (trim->done) {
*osamp = 0;
return (ST_EOF);
}
/* Default to assuming we will read all input data possible */
trim->index += done;
offset = 0;
/* Quick check to see if we are trimming off the back side yet.
* If so then we can skip trimming from the front side.
*/
if (! trim->trimmed) {
if (trim->start > trim->index) {
/* If we haven't read more then "start" samples, return that
* we've read all this buffer without outputing anything
*/
*osamp = 0;
return (ST_SUCCESS);
} else {
start_trim = 1;
/* We've read at least "start" samples. Now find
* out if we've read to much and if so compute a location
* to start copying data from. Also use this going forward
* as the amount of data read during trimmed check.
*/
offset = done - (trim->index - trim->start);
done = trim->index - trim->start;
}
} /* !trimmed */
if (trim->trimmed || start_trim ) {
if (trim->length && ( (trim->trimmed+done) > trim->length)) {
/* Compute the amount of unprocessed data left in this
* buffer and remove from isamp count and amount done.
*/
*isamp -= ((trim->trimmed+done) - trim->length);
done -= ((trim->trimmed+done) - trim->length);
*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;
{
trim_t trim = (trim_t) effp->priv;
if (trim->start_str)
free(trim->start_str);
if (trim->length_str)
free(trim->length_str);
return (ST_SUCCESS);
}