zerofill.3

来自「speech signal process tools」· 3 代码 · 共 110 行

.\" Copyright (c) 1989 Entropic Speech, Inc. All rights reserved.
.\" @(#)zerofill.3	1.2	02 May 1997	ESI
.TH ZERO_FILL 3\-ESPSsp 02 May 1997
.ds ]W "\fI\s+4\ze\h'0.05'e\s-4\v'-0.4m'\fP\(*p\v'0.4m'\ Entropic Speech, Inc.
.if t .ds - \(em\h'-0.2m'\(em
.if n .ds - ---
.SH NAME
zero_fill \- fill a newly allocated or existing numeric array with zeros
.SH SYNOPSIS
.ft B
.nf
#include <esps/esps.h>

char *
zero_fill(num, type, destination)
long	num;
int	type;
char    *destination;
.fi
.ft P
.SH DESCRIPTION
.PP
The function puts a specified number of zeros of a specified data type
into the result array,
which can either be an existing array or be allocated by the function.
.PP
The argument
.I num
gives the number of zeros to put into the array.
.PP
The argument
.I type
is a code that indicates the data type.
Legal values are the constants
DOUBLE, FLOAT, LONG, SHORT, BYTE,
DOUBLE_CPLX, FLOAT_CPLX, LONG_CPLX, SHORT_CPLX, and BYTE_CPLX
defined in the include file
.I esps/esps.h.
.PP
The argument
.I destination
must be either (char *) NULL
or the starting location of the storage area for the zeros.
If
.I destination
is NULL, the function will use
.IR malloc (3C)
to allocate an array to hold the zeros.
.PP
The value returned by
.I zero_fill
is a pointer to the starting location of the result array\*-\c
equal to
.I destination
if that is non-NULL,
and otherwise a pointer to the block of storage the function obtained from
.I malloc.
In either case the pointer must be cast to the proper type
.RI ( e.g.
(double *) if
.I type
is DOUBLE)
before being used.
.SH EXAMPLES
.nf
.ft I
/*
 * Zero out part of an existing array (elements a[200] through a[299]).
 */
.ft P
    double  a[500];

    (void) zero_fill(100, DOUBLE, (char *) &a[200]);

.ftI
/*
 * Allocate storage with malloc and fill with zeros.
 */
.ft P
    double_cplx *b;

    b = (double_cplx *) malloc((unsigned) 100 * sizeof(double_cplx));
    (void) zero_fill(100, DOUBLE_CPLX, (char *) b);

.ft I
/*
 * Repeatedly initialize an array with zeros.
 * This allocates storage the first time and thereafter reuses the same array.
 * The size must not increase after the first time.
 */
.ft P
    long    size = 100;
    short   *c = NULL;

    for ( . . . ) {
        . . .
        c = (short *) zero_fill(size, SHORT, (char *) c);
        . . .
    }
    free((char *) c);
.fi
.SH BUGS
.PP
None known.
.SH "SEE ALSO"
arr_op(3-ESPSsp), type_convert(3-ESPSu), malloc(3C), free(3C)
.PP
.SH AUTHOR
Rodney Johnson, ESI.