7fc1fa1654
1) Add FreeBSD: tag.
2) Add parenthesis around macro args.
3) Add parenthesis around macros which are expressions.
4) Add do { ... } while (0) around macros which are compound statements.
5) Sync bitstr_size and bit_alloc with neater versions from NetBSD.
6) Fix bit_ffs and bit_ffc so that they don't search off the end of the
bitstirng.
7) Try to avoid rightshifting signed ints.
I didn't take NetBSD's version directly as the macros are significantly
slower for long bitstrings. Bruce reviewed a previous version of
this patch.
PR: 21204
Submitted by: bob@immure.com
Reviewed by: bde
151 lines
5.1 KiB
C
151 lines
5.1 KiB
C
/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Paul Vixie.
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _BITSTRING_H_
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#define _BITSTRING_H_
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typedef unsigned char bitstr_t;
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/* internal macros */
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/* byte of the bitstring bit is in */
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#define _bit_byte(bit) \
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((bit) >> 3)
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/* mask for the bit within its byte */
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#define _bit_mask(bit) \
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(1 << ((bit)&0x7))
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/* external macros */
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/* bytes in a bitstring of nbits bits */
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#define bitstr_size(nbits) \
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(((nbits) + 7) >> 3)
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/* allocate a bitstring */
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#define bit_alloc(nbits) \
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(bitstr_t *)calloc((size_t)bitstr_size(nbits), sizeof(bitstr_t))
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/* allocate a bitstring on the stack */
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#define bit_decl(name, nbits) \
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((name)[bitstr_size(nbits)])
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/* is bit N of bitstring name set? */
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#define bit_test(name, bit) \
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((name)[_bit_byte(bit)] & _bit_mask(bit))
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/* set bit N of bitstring name */
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#define bit_set(name, bit) \
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((name)[_bit_byte(bit)] |= _bit_mask(bit))
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/* clear bit N of bitstring name */
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#define bit_clear(name, bit) \
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((name)[_bit_byte(bit)] &= ~_bit_mask(bit))
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/* clear bits start ... stop in bitstring */
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#define bit_nclear(name, start, stop) do { \
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register bitstr_t *_name = (name); \
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register int _start = (start), _stop = (stop); \
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register int _startbyte = _bit_byte(_start); \
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register int _stopbyte = _bit_byte(_stop); \
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if (_startbyte == _stopbyte) { \
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_name[_startbyte] &= ((0xff >> (8 - (_start&0x7))) | \
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(0xff << ((_stop&0x7) + 1))); \
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} else { \
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_name[_startbyte] &= 0xff >> (8 - (_start&0x7)); \
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while (++_startbyte < _stopbyte) \
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_name[_startbyte] = 0; \
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_name[_stopbyte] &= 0xff << ((_stop&0x7) + 1); \
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} \
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} while (0)
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/* set bits start ... stop in bitstring */
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#define bit_nset(name, start, stop) do { \
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register bitstr_t *_name = (name); \
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register int _start = (start), _stop = (stop); \
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register int _startbyte = _bit_byte(_start); \
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register int _stopbyte = _bit_byte(_stop); \
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if (_startbyte == _stopbyte) { \
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_name[_startbyte] |= ((0xff << (_start&0x7)) & \
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(0xff >> (7 - (_stop&0x7)))); \
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} else { \
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_name[_startbyte] |= 0xff << ((_start)&0x7); \
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while (++_startbyte < _stopbyte) \
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_name[_startbyte] = 0xff; \
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_name[_stopbyte] |= 0xff >> (7 - (_stop&0x7)); \
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} \
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} while (0)
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/* find first bit clear in name */
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#define bit_ffc(name, nbits, value) do { \
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register bitstr_t *_name = (name); \
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register int _byte, _nbits = (nbits); \
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register int _stopbyte = _bit_byte(_nbits - 1), _value = -1; \
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if (_nbits > 0) \
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for (_byte = 0; _byte <= _stopbyte; ++_byte) \
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if (_name[_byte] != 0xff) { \
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bitstr_t _lb; \
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_value = _byte << 3; \
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for (_lb = _name[_byte]; (_lb&0x1); \
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++_value, _lb >>= 1); \
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break; \
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} \
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if (_value >= nbits) \
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_value = -1; \
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*(value) = _value; \
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} while (0)
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/* find first bit set in name */
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#define bit_ffs(name, nbits, value) do { \
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register bitstr_t *_name = (name); \
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register int _byte, _nbits = (nbits); \
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register int _stopbyte = _bit_byte(_nbits - 1), _value = -1; \
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if (_nbits > 0) \
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for (_byte = 0; _byte <= _stopbyte; ++_byte) \
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if (_name[_byte]) { \
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bitstr_t _lb; \
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_value = _byte << 3; \
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for (_lb = _name[_byte]; !(_lb&0x1); \
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++_value, _lb >>= 1); \
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break; \
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} \
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if (_value >= nbits) \
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_value = -1; \
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*(value) = _value; \
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} while (0)
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#endif /* !_BITSTRING_H_ */
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