ref: 936818b32ddb701cb5726842fd1d09570270578f
dir: /src/skeleff.c/
/*
* skeleff - Skeleton Effect. Use as sample for new effects.
*
* Copyright 1999 Chris Bagwell And Sundry Contributors
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, write to the Free Software
* Foundation, Fifth Floor, 51 Franklin Street, Boston, MA 02111-1301,
* USA. */
#include "st_i.h"
/* Private data for effect */
typedef struct skeleff {
int localdata;
} *skeleff_t;
assert_static(sizeof(struct skeleff) <= ST_MAX_EFFECT_PRIVSIZE,
/* else */ skeleff_PRIVSIZE_too_big);
/*
* Process command-line options
*
* Don't do initialization now.
* The 'info' fields are not yet filled in.
*/
static int skeleff_getopts(eff_t effp, int n, char **argv)
{
skeleff_t skeleff = (skeleff_t)effp->priv;
if (n && n != 1) {
st_fail(effp->h->usage);
return ST_EOF;
}
return ST_SUCCESS;
}
/*
* Prepare processing.
* Do all initializations.
* If there's nothing to do, use st_effect_nothing instead.
*/
static int skeleff_start(eff_t effp)
{
if (effp->outinfo.channels == 1) {
st_fail("Can't run skeleff on mono data.");
return ST_EOF;
}
return ST_SUCCESS;
}
/*
* Processed signed long samples from ibuf to obuf.
* Return number of samples processed.
*/
static int skeleff_flow(eff_t effp, const st_sample_t *ibuf, st_sample_t *obuf,
st_size_t *isamp, st_size_t *osamp)
{
skeleff_t skeleff = (skeleff_t)effp->priv;
st_size_t len, done;
switch (effp->outinfo.channels) {
case 2:
/* Length to process will be buffer length / 2 since we
* work with two samples at a time.
*/
len = min(*isamp, *osamp) / 2;
for (done = 0; done < len; done++)
{
obuf[0] = ibuf[0];
obuf[1] = ibuf[1];
/* Advance buffer by 2 samples */
ibuf += 2;
obuf += 2;
}
*isamp = len * 2;
*osamp = len * 2;
break;
}
return ST_SUCCESS;
}
/*
* Drain out remaining samples if the effect generates any.
* If there's nothing to do, use st_effect_nothing_drain instead.
*/
static int skeleff_drain(eff_t effp, st_sample_t *obuf, st_size_t *osamp)
{
*osamp = 0;
/* Help out application and return ST_EOF when drain
* will not return any mre information. *osamp == 0
* also indicates that.
*/
return ST_EOF;
}
/*
* Do anything required when you stop reading samples.
* If there's nothing to do, use st_effect_nothing instead.
*/
static int skeleff_stop(eff_t effp)
{
return ST_SUCCESS;
}
/*
* Do anything required when you delete an effect.
* (free allocated memory, etc.)
* If there's nothing to do, use st_effect_nothing instead.
*/
static int skeleff_delete(eff_t effp)
{
return ST_SUCCESS;
}
/*
* Effect descriptor.
* If one of the methods does nothing, use the relevant
* st_effect_nothing* method.
*/
static st_effect_t st_skel_effect = {
"skel",
"Usage: skel [option]",
ST_EFF_MCHAN,
skeleff_getopts,
skeleff_start,
skeleff_flow,
skeleff_drain,
skeleff_stop,
skeleff_delete,
};
/*
* Function returning effect descriptor. This should be the only
* externally visible object.
*/
const st_effect_t *st_skel_effect_fn(void)
{
return &st_skel_effect;
}