295 lines
6.2 KiB
C
295 lines
6.2 KiB
C
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/* $NetBSD: bitops.h,v 1.7 2010/03/21 14:28:15 christos Exp $ */
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/*-
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* Copyright (c) 2007, 2010 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Christos Zoulas and Joerg Sonnenberger.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _SYS_BITOPS_H_
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#define _SYS_BITOPS_H_
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#include <sys/stdint.h>
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/*
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* Find First Set functions
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*/
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#ifndef ffs32
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static __inline int __unused
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ffs32(uint32_t _n)
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{
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int _v;
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if (!_n)
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return 0;
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_v = 1;
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if ((_n & 0x0000FFFFU) == 0) {
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_n >>= 16;
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_v += 16;
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}
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if ((_n & 0x000000FFU) == 0) {
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_n >>= 8;
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_v += 8;
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}
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if ((_n & 0x0000000FU) == 0) {
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_n >>= 4;
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_v += 4;
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}
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if ((_n & 0x00000003U) == 0) {
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_n >>= 2;
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_v += 2;
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}
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if ((_n & 0x00000001U) == 0) {
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_n >>= 1;
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_v += 1;
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}
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return _v;
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}
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#endif
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#ifndef ffs64
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static __inline int __unused
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ffs64(uint64_t _n)
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{
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int _v;
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if (!_n)
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return 0;
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_v = 1;
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if ((_n & 0x00000000FFFFFFFFULL) == 0) {
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_n >>= 32;
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_v += 32;
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}
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if ((_n & 0x000000000000FFFFULL) == 0) {
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_n >>= 16;
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_v += 16;
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}
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if ((_n & 0x00000000000000FFULL) == 0) {
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_n >>= 8;
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_v += 8;
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}
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if ((_n & 0x000000000000000FULL) == 0) {
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_n >>= 4;
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_v += 4;
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}
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if ((_n & 0x0000000000000003ULL) == 0) {
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_n >>= 2;
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_v += 2;
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}
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if ((_n & 0x0000000000000001ULL) == 0) {
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_n >>= 1;
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_v += 1;
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}
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return _v;
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}
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#endif
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/*
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* Find Last Set functions
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*/
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#ifndef fls32
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static __inline int __unused
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fls32(uint32_t _n)
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{
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int _v;
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if (!_n)
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return 0;
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_v = 32;
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if ((_n & 0xFFFF0000U) == 0) {
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_n <<= 16;
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_v -= 16;
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}
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if ((_n & 0xFF000000U) == 0) {
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_n <<= 8;
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_v -= 8;
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}
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if ((_n & 0xF0000000U) == 0) {
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_n <<= 4;
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_v -= 4;
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}
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if ((_n & 0xC0000000U) == 0) {
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_n <<= 2;
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_v -= 2;
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}
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if ((_n & 0x80000000U) == 0) {
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_n <<= 1;
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_v -= 1;
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}
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return _v;
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}
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#endif
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#ifndef fls64
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static __inline int __unused
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fls64(uint64_t _n)
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{
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int _v;
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if (!_n)
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return 0;
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_v = 64;
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if ((_n & 0xFFFFFFFF00000000ULL) == 0) {
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_n <<= 32;
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_v -= 32;
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}
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if ((_n & 0xFFFF000000000000ULL) == 0) {
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_n <<= 16;
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_v -= 16;
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}
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if ((_n & 0xFF00000000000000ULL) == 0) {
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_n <<= 8;
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_v -= 8;
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}
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if ((_n & 0xF000000000000000ULL) == 0) {
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_n <<= 4;
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_v -= 4;
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}
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if ((_n & 0xC000000000000000ULL) == 0) {
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_n <<= 2;
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_v -= 2;
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}
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if ((_n & 0x8000000000000000ULL) == 0) {
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_n <<= 1;
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_v -= 1;
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}
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return _v;
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}
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#endif
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/*
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* Integer logarithm, returns -1 on error. Inspired by the linux
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* version written by David Howells.
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*/
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#define _ilog2_helper(_n, _x) ((_n) & (1ULL << (_x))) ? _x :
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#define ilog2(_n) \
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( \
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__builtin_constant_p(_n) ? ( \
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_ilog2_helper(_n, 63) \
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_ilog2_helper(_n, 62) \
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_ilog2_helper(_n, 61) \
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_ilog2_helper(_n, 60) \
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_ilog2_helper(_n, 59) \
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_ilog2_helper(_n, 58) \
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_ilog2_helper(_n, 57) \
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_ilog2_helper(_n, 56) \
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_ilog2_helper(_n, 55) \
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_ilog2_helper(_n, 54) \
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_ilog2_helper(_n, 53) \
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_ilog2_helper(_n, 52) \
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_ilog2_helper(_n, 51) \
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_ilog2_helper(_n, 50) \
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_ilog2_helper(_n, 49) \
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_ilog2_helper(_n, 48) \
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_ilog2_helper(_n, 47) \
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_ilog2_helper(_n, 46) \
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_ilog2_helper(_n, 45) \
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_ilog2_helper(_n, 44) \
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_ilog2_helper(_n, 43) \
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_ilog2_helper(_n, 42) \
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_ilog2_helper(_n, 41) \
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_ilog2_helper(_n, 40) \
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_ilog2_helper(_n, 39) \
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_ilog2_helper(_n, 38) \
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_ilog2_helper(_n, 37) \
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_ilog2_helper(_n, 36) \
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_ilog2_helper(_n, 35) \
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_ilog2_helper(_n, 34) \
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_ilog2_helper(_n, 33) \
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_ilog2_helper(_n, 32) \
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_ilog2_helper(_n, 31) \
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_ilog2_helper(_n, 30) \
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_ilog2_helper(_n, 29) \
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_ilog2_helper(_n, 28) \
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_ilog2_helper(_n, 27) \
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_ilog2_helper(_n, 26) \
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_ilog2_helper(_n, 25) \
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_ilog2_helper(_n, 24) \
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_ilog2_helper(_n, 23) \
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_ilog2_helper(_n, 22) \
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_ilog2_helper(_n, 21) \
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_ilog2_helper(_n, 20) \
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_ilog2_helper(_n, 19) \
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_ilog2_helper(_n, 18) \
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_ilog2_helper(_n, 17) \
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_ilog2_helper(_n, 16) \
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_ilog2_helper(_n, 15) \
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_ilog2_helper(_n, 14) \
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_ilog2_helper(_n, 13) \
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_ilog2_helper(_n, 12) \
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_ilog2_helper(_n, 11) \
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_ilog2_helper(_n, 10) \
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_ilog2_helper(_n, 9) \
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_ilog2_helper(_n, 8) \
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_ilog2_helper(_n, 7) \
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_ilog2_helper(_n, 6) \
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_ilog2_helper(_n, 5) \
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_ilog2_helper(_n, 4) \
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_ilog2_helper(_n, 3) \
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_ilog2_helper(_n, 2) \
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_ilog2_helper(_n, 1) \
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_ilog2_helper(_n, 0) \
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-1) : ((sizeof(_n) >= 4 ? fls64(_n) : fls32(_n)) - 1) \
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)
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static __inline void
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fast_divide32_prepare(uint32_t _div, uint32_t * __restrict _m,
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uint8_t *__restrict _s1, uint8_t *__restrict _s2)
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{
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uint64_t _mt;
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int _l;
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_l = fls32(_div - 1);
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_mt = 0x100000000ULL * ((1ULL << _l) - _div);
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*_m = (uint32_t)(_mt / _div + 1);
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*_s1 = (_l > 1) ? 1 : _l;
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*_s2 = (_l == 0) ? 0 : _l - 1;
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}
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/* ARGSUSED */
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static __inline uint32_t
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fast_divide32(uint32_t _v, uint32_t _div, uint32_t _m, uint8_t _s1,
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uint8_t _s2)
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{
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uint32_t _t;
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_t = (uint32_t)(((uint64_t)_v * _m) >> 32);
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return (_t + ((_v - _t) >> _s1)) >> _s2;
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}
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static __inline uint32_t
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fast_remainder32(uint32_t _v, uint32_t _div, uint32_t _m, uint8_t _s1,
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uint8_t _s2)
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{
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return _v - _div * fast_divide32(_v, _div, _m, _s1, _s2);
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}
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#endif /* _SYS_BITOPS_H_ */
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