ref: 9dd22e5ec99577e56bf5225a121e3d78e72ef790
dir: /src/reverse.c/
/* * June 1, 1992 * Copyright 1992 Guido van Rossum And Sundry Contributors * This source code is freely redistributable and may be used for * any purpose. This copyright notice must be maintained. * Guido van Rossum And Sundry Contributors are not responsible for * the consequences of using this software. */ /* * "reverse" effect, uses a temporary file created by tmpfile(). */ #include <math.h> #include <stdio.h> #ifdef HAVE_UNISTD_H #include <unistd.h> /* For SEEK_* defines if not found in stdio */ #endif #include "st_i.h" /* Private data */ typedef struct reversestuff { FILE *fp; st_size_t pos; int phase; } *reverse_t; #define WRITING 0 #define READING 1 /* * Process options: none in our case. */ int st_reverse_getopts(eff_t effp, int n, char **argv) { if (n) { st_fail("Reverse effect takes no options."); return (ST_EOF); } return(ST_SUCCESS); } /* * Prepare processing: open temporary file. */ int st_reverse_start(eff_t effp) { reverse_t reverse = (reverse_t) effp->priv; reverse->fp = tmpfile(); if (reverse->fp == NULL) { st_fail("Reverse effect can't create temporary file\n"); return (ST_EOF); } reverse->phase = WRITING; return (ST_SUCCESS); } /* * Effect flow: a degenerate case: write input samples on temporary file, * don't generate any output samples. */ int st_reverse_flow(eff_t effp, st_sample_t *ibuf, st_sample_t *obuf, st_size_t *isamp, st_size_t *osamp) { reverse_t reverse = (reverse_t) effp->priv; if (reverse->phase != WRITING) { st_fail("Internal error: reverse_flow called in wrong phase"); return(ST_EOF); } if (fwrite((char *)ibuf, sizeof(st_sample_t), *isamp, reverse->fp) != *isamp) { st_fail("Reverse effect write error on temporary file\n"); return(ST_EOF); } *osamp = 0; return(ST_SUCCESS); } /* * Effect drain: generate the actual samples in reverse order. */ int st_reverse_drain(eff_t effp, st_sample_t *obuf, st_size_t *osamp) { reverse_t reverse = (reverse_t) effp->priv; st_size_t len, nbytes; register int i, j; st_sample_t temp; if (reverse->phase == WRITING) { fflush(reverse->fp); fseek(reverse->fp, 0L, SEEK_END); reverse->pos = ftell(reverse->fp); if (reverse->pos % sizeof(st_sample_t) != 0) { st_fail("Reverse effect finds odd temporary file\n"); return(ST_EOF); } reverse->phase = READING; } len = *osamp; nbytes = len * sizeof(st_sample_t); if (reverse->pos < nbytes) { nbytes = reverse->pos; len = nbytes / sizeof(st_sample_t); } reverse->pos -= nbytes; fseek(reverse->fp, reverse->pos, SEEK_SET); if (fread((char *)obuf, sizeof(st_sample_t), len, reverse->fp) != len) { st_fail("Reverse effect read error from temporary file\n"); return(ST_EOF); } for (i = 0, j = len-1; i < j; i++, j--) { temp = obuf[i]; obuf[i] = obuf[j]; obuf[j] = temp; } *osamp = len; return(ST_SUCCESS); } /* * Close and unlink the temporary file. */ int st_reverse_stop(eff_t effp) { reverse_t reverse = (reverse_t) effp->priv; fclose(reverse->fp); return (ST_SUCCESS); }