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