2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 2004, 2005 David Young. All rights reserved.
6 * Programmed for NetBSD by David Young.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of David Young may not be used to endorse or promote
17 * products derived from this software without specific prior
20 * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
21 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
22 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
23 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL David
24 * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
26 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
28 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
33 * $DragonFly: src/sys/dev/netif/bwi/bitops.h,v 1.1 2007/09/08 06:15:54 sephe Exp $
41 * __BIT(n): Return a bitmask with bit m set, where the least
42 * significant bit is bit 0.
44 * __BITS(m, n): Return a bitmask with bits m through n, inclusive,
45 * set. It does not matter whether m>n or m<=n. The
46 * least significant bit is bit 0.
48 * A "bitfield" is a span of consecutive bits defined by a bitmask,
49 * where 1s select the bits in the bitfield. __SHIFTIN, __SHIFTOUT,
50 * and SHIFTOUT_MASK help read and write bitfields from device registers.
52 * __SHIFTIN(v, mask): Left-shift bits `v' into the bitfield
53 * defined by `mask', and return them. No
56 * __SHIFTOUT(v, mask): Extract and return the bitfield selected
57 * by `mask' from `v', right-shifting the
58 * bits so that the rightmost selected bit
59 * is at bit 0. No side-effects.
61 * __SHIFTOUT_MASK(mask): Right-shift the bits in `mask' so that
62 * the rightmost non-zero bit is at bit
63 * 0. This is useful for finding the
64 * greatest unsigned value that a bitfield
65 * can hold. No side-effects. Note that
66 * SHIFTOUT_MASK(m) = SHIFTOUT(m, m).
69 /* __BIT(n): nth bit, where __BIT(0) == 0x1. */
70 #define __BIT(__n) (((__n) == 32) ? 0 : ((uint32_t)1 << (__n)))
72 /* __BITS(m, n): bits m through n, m < n. */
73 #define __BITS(__m, __n) \
74 ((__BIT(MAX((__m), (__n)) + 1) - 1) ^ (__BIT(MIN((__m), (__n))) - 1))
76 /* Find least significant bit that is set */
77 #define __LOWEST_SET_BIT(__mask) ((((__mask) - 1) & (__mask)) ^ (__mask))
79 #define __SHIFTOUT(__x, __mask) (((__x) & (__mask)) / __LOWEST_SET_BIT(__mask))
80 #define __SHIFTIN(__x, __mask) ((__x) * __LOWEST_SET_BIT(__mask))
81 #define __SHIFTOUT_MASK(__mask) __SHIFTOUT((__mask), (__mask))
83 #endif /* !_BITOPS_H */