/* * 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/sys/bitops.h,v 1.1 2007/10/14 04:15:17 sephe Exp $ */ #ifndef _SYS_BITOPS_H_ #define _SYS_BITOPS_H_ /* * __BIT(n): Return a bitmask with bit n 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))) #define __BIT64(__n) (((__n) == 64) ? 0 : ((uint64_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)) #define __BITS64(__m, __n) \ ((__BIT64(MAX((__m), (__n)) + 1) - 1) ^ \ (__BIT64(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)) /* * Integer logarithm, returns -1 on error. * Inspired by the linux version written by David Howells. */ #define _ilog2_helper(_n, _x) ((_n) & (1ULL << (_x))) ? _x : #define _ilog2_const(_n) \ ( \ _ilog2_helper(_n, 63) \ _ilog2_helper(_n, 62) \ _ilog2_helper(_n, 61) \ _ilog2_helper(_n, 60) \ _ilog2_helper(_n, 59) \ _ilog2_helper(_n, 58) \ _ilog2_helper(_n, 57) \ _ilog2_helper(_n, 56) \ _ilog2_helper(_n, 55) \ _ilog2_helper(_n, 54) \ _ilog2_helper(_n, 53) \ _ilog2_helper(_n, 52) \ _ilog2_helper(_n, 51) \ _ilog2_helper(_n, 50) \ _ilog2_helper(_n, 49) \ _ilog2_helper(_n, 48) \ _ilog2_helper(_n, 47) \ _ilog2_helper(_n, 46) \ _ilog2_helper(_n, 45) \ _ilog2_helper(_n, 44) \ _ilog2_helper(_n, 43) \ _ilog2_helper(_n, 42) \ _ilog2_helper(_n, 41) \ _ilog2_helper(_n, 40) \ _ilog2_helper(_n, 39) \ _ilog2_helper(_n, 38) \ _ilog2_helper(_n, 37) \ _ilog2_helper(_n, 36) \ _ilog2_helper(_n, 35) \ _ilog2_helper(_n, 34) \ _ilog2_helper(_n, 33) \ _ilog2_helper(_n, 32) \ _ilog2_helper(_n, 31) \ _ilog2_helper(_n, 30) \ _ilog2_helper(_n, 29) \ _ilog2_helper(_n, 28) \ _ilog2_helper(_n, 27) \ _ilog2_helper(_n, 26) \ _ilog2_helper(_n, 25) \ _ilog2_helper(_n, 24) \ _ilog2_helper(_n, 23) \ _ilog2_helper(_n, 22) \ _ilog2_helper(_n, 21) \ _ilog2_helper(_n, 20) \ _ilog2_helper(_n, 19) \ _ilog2_helper(_n, 18) \ _ilog2_helper(_n, 17) \ _ilog2_helper(_n, 16) \ _ilog2_helper(_n, 15) \ _ilog2_helper(_n, 14) \ _ilog2_helper(_n, 13) \ _ilog2_helper(_n, 12) \ _ilog2_helper(_n, 11) \ _ilog2_helper(_n, 10) \ _ilog2_helper(_n, 9) \ _ilog2_helper(_n, 8) \ _ilog2_helper(_n, 7) \ _ilog2_helper(_n, 6) \ _ilog2_helper(_n, 5) \ _ilog2_helper(_n, 4) \ _ilog2_helper(_n, 3) \ _ilog2_helper(_n, 2) \ _ilog2_helper(_n, 1) \ _ilog2_helper(_n, 0) \ -1 \ ) #define ilog2(_n) \ ( \ __builtin_constant_p(_n) ? _ilog2_const(_n) : \ ((sizeof(_n) > 4 ? flsl(_n) : fls(_n)) - 1) \ ) #endif /* !_SYS_BITOPS_H_ */
