1 /* 2 * Copyright (c) 2004, 2005 David Young. All rights reserved. 3 * 4 * Programmed for NetBSD by David Young. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of David Young may not be used to endorse or promote 15 * products derived from this software without specific prior 16 * written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY 19 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 20 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 21 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL David 22 * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 23 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 24 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 26 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 27 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 29 * OF SUCH DAMAGE. 30 * 31 * $DragonFly: src/sys/dev/netif/bwi/bitops.h,v 1.1 2007/09/08 06:15:54 sephe Exp $ 32 * $FreeBSD$ 33 */ 34 35 #ifndef _BITOPS_H 36 #define _BITOPS_H 37 38 /* 39 * __BIT(n): Return a bitmask with bit m set, where the least 40 * significant bit is bit 0. 41 * 42 * __BITS(m, n): Return a bitmask with bits m through n, inclusive, 43 * set. It does not matter whether m>n or m<=n. The 44 * least significant bit is bit 0. 45 * 46 * A "bitfield" is a span of consecutive bits defined by a bitmask, 47 * where 1s select the bits in the bitfield. __SHIFTIN, __SHIFTOUT, 48 * and SHIFTOUT_MASK help read and write bitfields from device registers. 49 * 50 * __SHIFTIN(v, mask): Left-shift bits `v' into the bitfield 51 * defined by `mask', and return them. No 52 * side-effects. 53 * 54 * __SHIFTOUT(v, mask): Extract and return the bitfield selected 55 * by `mask' from `v', right-shifting the 56 * bits so that the rightmost selected bit 57 * is at bit 0. No side-effects. 58 * 59 * __SHIFTOUT_MASK(mask): Right-shift the bits in `mask' so that 60 * the rightmost non-zero bit is at bit 61 * 0. This is useful for finding the 62 * greatest unsigned value that a bitfield 63 * can hold. No side-effects. Note that 64 * SHIFTOUT_MASK(m) = SHIFTOUT(m, m). 65 */ 66 67 /* __BIT(n): nth bit, where __BIT(0) == 0x1. */ 68 #define __BIT(__n) (((__n) == 32) ? 0 : ((uint32_t)1 << (__n))) 69 70 /* __BITS(m, n): bits m through n, m < n. */ 71 #define __BITS(__m, __n) \ 72 ((__BIT(MAX((__m), (__n)) + 1) - 1) ^ (__BIT(MIN((__m), (__n))) - 1)) 73 74 /* Find least significant bit that is set */ 75 #define __LOWEST_SET_BIT(__mask) ((((__mask) - 1) & (__mask)) ^ (__mask)) 76 77 #define __SHIFTOUT(__x, __mask) (((__x) & (__mask)) / __LOWEST_SET_BIT(__mask)) 78 #define __SHIFTIN(__x, __mask) ((__x) * __LOWEST_SET_BIT(__mask)) 79 #define __SHIFTOUT_MASK(__mask) __SHIFTOUT((__mask), (__mask)) 80 81 #endif /* !_BITOPS_H */ 82