ref: f0230901289e423cd58430d51b9e60951b3f1417
dir: /nul.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.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) 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"; /* only SIGINT will stop us from reading nul data.. * */ sigintreg(ft); /* Prepare to catch SIGINT */ return (ST_SUCCESS); } /* * Read up to len samples, we read always '0' * Convert to signed longs. * Place in buf[]. * Return number of samples read. */ LONG st_nulread(ft, buf, len) ft_t ft; LONG *buf, len; { nul_t sk = (nul_t) ft->priv; int done = 0; LONG 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) ft_t ft; { return (ST_SUCCESS); } int st_nulstartwrite(ft) ft_t ft; { nul_t sk = (nul_t) ft->priv; sk->writesamples=0; return(ST_SUCCESS); } LONG st_nulwrite(ft, buf, len) ft_t ft; LONG *buf, 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) ft_t ft; { /* nothing to do */ return (ST_SUCCESS); }