152 lines
4.0 KiB
Groff
152 lines
4.0 KiB
Groff
.\" $NetBSD: bitmap.3,v 1.12 2018/03/08 06:47:30 wiz Exp $
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.\"
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.\" Copyright (c) 2012 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Christos Zoulas.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd March 8, 2018
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.Dt BITMAP 3
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.Os
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.Sh NAME
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.Nm __BITMAP_CLR ,
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.Nm __BITMAP_ISSET ,
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.Nm __BITMAP_SET ,
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.Nm __BITMAP_SIZE ,
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.Nm __BITMAP_TYPE ,
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.Nm __BITMAP_ZERO
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.Nd bitmap manipulation macros
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/bitops.h
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.Fn __BITMAP_CLR "int bit" "type *bitmap"
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.Fn __BITMAP_ISSET "int bit" "type *bitmap"
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.Fn __BITMAP_SET "int bit" "type *bitmap"
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.Fn __BITMAP_SIZE "type" "int nbits"
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.Fn __BITMAP_TYPE "name" "type" "int nbits"
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.Fn __BITMAP_ZERO "type *bitmap"
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.Sh DESCRIPTION
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The supplied macros are similar to the
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.Xr select 2
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.Fn FD_SET
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family, to the
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.Xr setbit 9 ,
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macros and the
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.Xr bitstring 3
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library.
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They are different from
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.Fn FD_SET
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because they are designed to handle multiple sized bitmaps at the same time,
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and they can be of any integral type.
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They are different from
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.Xr setbit 9
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because they can operate on different integral types, not just on bytes.
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They are different from
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.Xr bitstring 3
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because they are just macros, they don't allocate memory or use code,
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and they can be used in both kernel and userland.
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.Pp
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The following macros are provided for manipulating creating and manipulating
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bitmaps:
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.Pp
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.Fn __BITMAP_CLR bit bitmap
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removes the given
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.Fa bit
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from the
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.Fa bitmap .
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.Pp
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.Fn __BITMAP_ISSET bit bitmap
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is non-zero if
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.Fa bit
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is a member of
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.Fa bitmap ,
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zero otherwise.
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.Pp
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.Fn __BITMAP_SET bit bitmap
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Sets the given
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.Fa bit
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in the
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.Fa bitmap .
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.Pp
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.Fn __BITMAP_SIZE type nbits
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Returns the number of elements would be required of the given
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.Fa type
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to hold
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.Fa nbits .
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.Pp
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.Fn __BITMAP_TYPE name type nbits
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Declares the properly sized bitmap structure
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of the given
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.Fa type
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that holds
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.Fa nbits
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and is named
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.Fa name .
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.Pp
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.Fn __BITMAP_ZERO bitmap
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initializes a descriptor set pointed to by
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.Fa bitmap
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to the null set.
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.Pp
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The behavior of these macros is undefined for negative
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bit values or ones greater than the number of bits the bitmap can hold.
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.Sh EXAMPLES
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.Bd -literal
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#include <sys/bitops.h>
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int
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main(int argc, char **argv)
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{
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__BITMAP_TYPE(, uint32_t, 5000) bitmap;
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/* Initialize the read set to null */
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__BITMAP_ZERO(&bitmap);
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/* Set bit 1 */
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__BITMAP_SET(1, &bitmap);
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for (size_t i = 0; i < 5000; i++) {
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if (__BITMAP_ISSET(i, &bitmap)) {
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/* Should just print 1 */
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printf("Bit %zu is set\en", i);
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__BITMAP_CLR(i, &bitmap);
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}
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break;
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}
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return 0;
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}
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.Ed
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.Sh SEE ALSO
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.Xr select 2 ,
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.Xr bitops 3 ,
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.Xr bitstring 3 ,
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.Xr setbit 9
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.Sh HISTORY
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The
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.Fn __BITMAP_*
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macros appeared in
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.Nx 7.0 .
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