82 lines
3.5 KiB
C
82 lines
3.5 KiB
C
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/*
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* Copyright (c) 2004, 2005 David Young. All rights reserved.
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*
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* Programmed for NetBSD by David Young.
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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. The name of David Young may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL David
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* Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* 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
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* OF SUCH DAMAGE.
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*
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* $DragonFly: src/sys/dev/netif/bwi/bitops.h,v 1.1 2007/09/08 06:15:54 sephe Exp $
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* $FreeBSD$
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*/
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#ifndef _BITOPS_H
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#define _BITOPS_H
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/*
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* __BIT(n): Return a bitmask with bit m set, where the least
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* significant bit is bit 0.
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*
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* __BITS(m, n): Return a bitmask with bits m through n, inclusive,
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* set. It does not matter whether m>n or m<=n. The
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* least significant bit is bit 0.
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*
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* A "bitfield" is a span of consecutive bits defined by a bitmask,
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* where 1s select the bits in the bitfield. __SHIFTIN, __SHIFTOUT,
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* and SHIFTOUT_MASK help read and write bitfields from device registers.
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*
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* __SHIFTIN(v, mask): Left-shift bits `v' into the bitfield
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* defined by `mask', and return them. No
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* side-effects.
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*
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* __SHIFTOUT(v, mask): Extract and return the bitfield selected
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* by `mask' from `v', right-shifting the
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* bits so that the rightmost selected bit
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* is at bit 0. No side-effects.
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*
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* __SHIFTOUT_MASK(mask): Right-shift the bits in `mask' so that
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* the rightmost non-zero bit is at bit
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* 0. This is useful for finding the
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* greatest unsigned value that a bitfield
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* can hold. No side-effects. Note that
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* SHIFTOUT_MASK(m) = SHIFTOUT(m, m).
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*/
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/* __BIT(n): nth bit, where __BIT(0) == 0x1. */
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#define __BIT(__n) (((__n) == 32) ? 0 : ((uint32_t)1 << (__n)))
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/* __BITS(m, n): bits m through n, m < n. */
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#define __BITS(__m, __n) \
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((__BIT(MAX((__m), (__n)) + 1) - 1) ^ (__BIT(MIN((__m), (__n))) - 1))
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/* Find least significant bit that is set */
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#define __LOWEST_SET_BIT(__mask) ((((__mask) - 1) & (__mask)) ^ (__mask))
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#define __SHIFTOUT(__x, __mask) (((__x) & (__mask)) / __LOWEST_SET_BIT(__mask))
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#define __SHIFTIN(__x, __mask) ((__x) * __LOWEST_SET_BIT(__mask))
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#define __SHIFTOUT_MASK(__mask) __SHIFTOUT((__mask), (__mask))
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#endif /* !_BITOPS_H */
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