ref: ed4bb590c611e4310b9540efb5049a7025c36325
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.
*/
#include "sox_i.h"
#include <string.h>
typedef struct {
/* options here */
char *start_str;
char *end_str;
sox_bool end_is_absolute;
/* options converted to values */
uint64_t start;
uint64_t length;
/* internal stuff */
uint64_t index;
uint64_t trimmed;
} priv_t;
/*
* Process options
*/
static int sox_trim_getopts(sox_effect_t * effp, int argc, char **argv)
{
char *end;
priv_t * trim = (priv_t *) effp->priv;
uint64_t samples;
const char *n;
--argc, ++argv;
/* Do not know sample rate yet so hold off on completely parsing
* time related strings.
*/
switch (argc) {
case 2:
end = argv[1];
if (*end == '=') {
trim->end_is_absolute = sox_true;
end++;
} else trim->end_is_absolute = sox_false;
trim->end_str = lsx_strdup(end);
/* Do a dummy parse to see if it will fail */
n = lsx_parsesamples(0., trim->end_str, &samples, 't');
if (!n || *n)
return lsx_usage(effp);
trim->length = samples;
case 1:
trim->start_str = lsx_strdup(argv[0]);
/* Do a dummy parse to see if it will fail */
n = lsx_parsesamples(0., trim->start_str, &samples, 't');
if (!n || *n)
return lsx_usage(effp);
trim->start = samples;
break;
default:
return lsx_usage(effp);
}
return (SOX_SUCCESS);
}
/*
* Start processing
*/
static int sox_trim_start(sox_effect_t * effp)
{
priv_t * trim = (priv_t *) effp->priv;
uint64_t samples;
if (lsx_parsesamples(effp->in_signal.rate, trim->start_str,
&samples, 't') == NULL)
return lsx_usage(effp);
trim->start = samples;
if (trim->end_str)
{
if (lsx_parsesamples(effp->in_signal.rate, trim->end_str,
&samples, 't') == NULL)
return lsx_usage(effp);
trim->length = samples;
if (trim->end_is_absolute) {
if (trim->length < trim->start) {
lsx_warn("end earlier than start");
trim->length = 0;
/* with trim->end_str != NULL, this really means zero */
} else
trim->length -= trim->start;
}
}
else
trim->length = 0;
/* with trim->end_str == NULL, this means indefinite length */
lsx_debug("start at %" PRIu64 ", length %" PRIu64, trim->start, trim->length);
/* Account for # of channels */
trim->start *= effp->in_signal.channels;
trim->length *= effp->in_signal.channels;
trim->index = 0;
trim->trimmed = 0;
if (effp->in_signal.length) {
if (trim->start >= effp->in_signal.length) {
lsx_fail("start position after end of file");
return SOX_EOF;
} else if (trim->start + trim->length >= effp->in_signal.length) {
lsx_fail("end position after end of file");
return SOX_EOF;
}
}
effp->out_signal.length = trim->length;
if (!effp->out_signal.length && effp->in_signal.length > trim->start)
effp->out_signal.length = effp->in_signal.length - trim->start;
return (SOX_SUCCESS);
}
/*
* Read up to len samples from file.
* Convert to signed longs.
* Place in buf[].
* Return number of samples read.
*/
static int sox_trim_flow(sox_effect_t * effp, const sox_sample_t *ibuf, sox_sample_t *obuf,
size_t *isamp, size_t *osamp)
{
int result = SOX_SUCCESS;
int start_trim = 0;
int offset = 0;
int done;
priv_t * trim = (priv_t *) effp->priv;
/* Compute the most samples we can process this time */
done = ((*isamp < *osamp) ? *isamp : *osamp);
/* 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->index+done) <= trim->start) {
/* If we haven't read more than "start" samples, return that
* we've read all this buffer without outputing anything
*/
*osamp = 0;
*isamp = done;
trim->index += done;
return (SOX_SUCCESS);
} else {
start_trim = 1;
/* We've read at least "start" samples. Now find
* out where our target data begins and subtract that
* from the total to be copied this round.
*/
offset = trim->start - trim->index;
done -= offset;
}
} /* !trimmed */
if (trim->trimmed || start_trim) {
if (trim->end_str && ((trim->trimmed+done) >= trim->length)) {
/* Since we know the end is in this block, we set done
* to the desired length less the amount already read.
*/
done = trim->length - trim->trimmed;
result = SOX_EOF;
}
trim->trimmed += done;
}
memcpy(obuf, ibuf+offset, done * sizeof(*obuf));
*osamp = done;
*isamp = offset + done;
trim->index += done;
return result;
}
static int lsx_kill(sox_effect_t * effp)
{
priv_t * trim = (priv_t *) effp->priv;
free(trim->start_str);
free(trim->end_str);
return (SOX_SUCCESS);
}
sox_uint64_t sox_trim_get_start(sox_effect_t * effp)
{
priv_t * trim = (priv_t *)effp->priv;
return trim->start;
}
void sox_trim_clear_start(sox_effect_t * effp)
{
priv_t * trim = (priv_t *)effp->priv;
trim->start = 0;
}
const sox_effect_handler_t *lsx_trim_effect_fn(void)
{
static sox_effect_handler_t handler = {
"trim", "start [length|=end]", SOX_EFF_MCHAN | SOX_EFF_LENGTH | SOX_EFF_MODIFY,
sox_trim_getopts, sox_trim_start, sox_trim_flow,
NULL, NULL, lsx_kill, sizeof(priv_t)
};
return &handler;
}