1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2004, 2005 David Young. All rights reserved. 5 * 6 * Programmed for NetBSD by David Young. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 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 18 * written permission. 19 * 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 31 * OF SUCH DAMAGE. 32 * 33 * $DragonFly: src/sys/dev/netif/bwi/bitops.h,v 1.1 2007/09/08 06:15:54 sephe Exp $ 34 * $FreeBSD$ 35 */ 36 37 #ifndef _BITOPS_H 38 #define _BITOPS_H 39 40 /* 41 * __BIT(n): Return a bitmask with bit m set, where the least 42 * significant bit is bit 0. 43 * 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. 47 * 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. 51 * 52 * __SHIFTIN(v, mask): Left-shift bits `v' into the bitfield 53 * defined by `mask', and return them. No 54 * side-effects. 55 * 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. 60 * 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). 67 */ 68 69 /* __BIT(n): nth bit, where __BIT(0) == 0x1. */ 70 #define __BIT(__n) (((__n) == 32) ? 0 : ((uint32_t)1 << (__n))) 71 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)) 75 76 /* Find least significant bit that is set */ 77 #define __LOWEST_SET_BIT(__mask) ((((__mask) - 1) & (__mask)) ^ (__mask)) 78 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)) 82 83 #endif /* !_BITOPS_H */ 84