ref: 03df8e0fd971d42cb37746eeef9a017bd0a1e766
dir: /src/nulfile.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 nul file format driver.
* Written by Carsten Borchardt
* The author is not responsible for the consequences
* of using this software
*
*/
#include <math.h>
#include "st_i.h"
/* Private data for nul file */
typedef struct nulstuff {
int rest; /* bytes remaining in current block */
unsigned long readsamples;
unsigned long writesamples;
} *nul_t;
/*
* Do anything required before you start reading samples.
* Read file header.
* Find out sampling rate,
* size and encoding of samples,
* mono/stereo/quad.
*/
int st_nulstartread(ft_t ft)
{
nul_t sk = (nul_t) ft->priv;
/* no samples read yet */
sk->readsamples=0;
/* if no input rate is given as parameter, switch to
* default parameter
*/
if(ft->info.rate == 0){
/* input rate not set, switch to default */
ft->info.rate = 44100;
ft->info.size = ST_SIZE_WORD;
ft->info.encoding = ST_ENCODING_SIGN2;
ft->info.channels = 2;
}
ft->comment = "nul file";
return (ST_SUCCESS);
}
/*
* Read up to len samples, we read always '0'
* Convert to signed longs.
* Place in buf[].
* Return number of samples read.
*/
st_ssize_t st_nulread(ft_t ft, st_sample_t *buf, st_ssize_t len)
{
nul_t sk = (nul_t) ft->priv;
int done = 0;
st_sample_t l;
for(; done < len; done++) {
if (ft->file.eof)
break;
l = 0; /* nul samples are always 0 */
sk->readsamples++;
*buf++ = l;
}
return done;
}
/*
* Do anything required when you stop reading samples.
* Don't close input file!
* .. nothing to be done
*/
int st_nulstopread(ft_t ft)
{
return (ST_SUCCESS);
}
int st_nulstartwrite(ft_t ft)
{
nul_t sk = (nul_t) ft->priv;
sk->writesamples=0;
return(ST_SUCCESS);
}
st_ssize_t st_nulwrite(ft_t ft, st_sample_t *buf, st_ssize_t len)
{
nul_t sk = (nul_t) ft->priv;
while(len--)
sk->writesamples++;
st_writeb(ft, (*buf++ >> 24) ^ 0x80);
return (ST_SUCCESS);
}
int st_nulstopwrite(ft_t ft)
{
/* nothing to do */
return (ST_SUCCESS);
}
static char *nulnames[] = {
"nul",
NULL,
};
st_format_t st_nul_format = {
nulnames,
NULL,
ST_FILE_STEREO | ST_FILE_NOSTDIO,
st_nulstartread,
st_nulread,
st_nulstopread,
st_nulstartwrite,
st_nulwrite,
st_nulstopwrite,
st_format_nothing_seek
};