1 /* 2 * Copyright (c) 2008-2020 Stefan Krah. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 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 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 29 #ifndef LIBMPDEC_BITS_H_ 30 #define LIBMPDEC_BITS_H_ 31 32 33 #include "mpdecimal.h" 34 35 36 /* Check if n is a power of 2. */ 37 static inline int ispower2(mpd_size_t n)38 ispower2(mpd_size_t n) 39 { 40 return n != 0 && (n & (n-1)) == 0; 41 } 42 43 #if defined(ANSI) 44 /* 45 * Return the most significant bit position of n from 0 to 31 (63). 46 * Assumptions: n != 0. 47 */ 48 static inline int mpd_bsr(mpd_size_t n)49 mpd_bsr(mpd_size_t n) 50 { 51 int pos = 0; 52 mpd_size_t tmp; 53 54 #ifdef CONFIG_64 55 tmp = n >> 32; 56 if (tmp != 0) { n = tmp; pos += 32; } 57 #endif 58 tmp = n >> 16; 59 if (tmp != 0) { n = tmp; pos += 16; } 60 tmp = n >> 8; 61 if (tmp != 0) { n = tmp; pos += 8; } 62 tmp = n >> 4; 63 if (tmp != 0) { n = tmp; pos += 4; } 64 tmp = n >> 2; 65 if (tmp != 0) { n = tmp; pos += 2; } 66 tmp = n >> 1; 67 if (tmp != 0) { n = tmp; pos += 1; } 68 69 return pos + (int)n - 1; 70 } 71 72 /* 73 * Return the least significant bit position of n from 0 to 31 (63). 74 * Assumptions: n != 0. 75 */ 76 static inline int mpd_bsf(mpd_size_t n)77 mpd_bsf(mpd_size_t n) 78 { 79 int pos; 80 81 #ifdef CONFIG_64 82 pos = 63; 83 if (n & 0x00000000FFFFFFFFULL) { pos -= 32; } else { n >>= 32; } 84 if (n & 0x000000000000FFFFULL) { pos -= 16; } else { n >>= 16; } 85 if (n & 0x00000000000000FFULL) { pos -= 8; } else { n >>= 8; } 86 if (n & 0x000000000000000FULL) { pos -= 4; } else { n >>= 4; } 87 if (n & 0x0000000000000003ULL) { pos -= 2; } else { n >>= 2; } 88 if (n & 0x0000000000000001ULL) { pos -= 1; } 89 #else 90 pos = 31; 91 if (n & 0x000000000000FFFFUL) { pos -= 16; } else { n >>= 16; } 92 if (n & 0x00000000000000FFUL) { pos -= 8; } else { n >>= 8; } 93 if (n & 0x000000000000000FUL) { pos -= 4; } else { n >>= 4; } 94 if (n & 0x0000000000000003UL) { pos -= 2; } else { n >>= 2; } 95 if (n & 0x0000000000000001UL) { pos -= 1; } 96 #endif 97 return pos; 98 } 99 /* END ANSI */ 100 101 #elif defined(ASM) 102 /* 103 * Bit scan reverse. Assumptions: a != 0. 104 */ 105 static inline int mpd_bsr(mpd_size_t a)106 mpd_bsr(mpd_size_t a) 107 { 108 mpd_size_t retval; 109 110 __asm__ ( 111 #ifdef CONFIG_64 112 "bsrq %1, %0\n\t" 113 #else 114 "bsr %1, %0\n\t" 115 #endif 116 :"=r" (retval) 117 :"r" (a) 118 :"cc" 119 ); 120 121 return (int)retval; 122 } 123 124 /* 125 * Bit scan forward. Assumptions: a != 0. 126 */ 127 static inline int mpd_bsf(mpd_size_t a)128 mpd_bsf(mpd_size_t a) 129 { 130 mpd_size_t retval; 131 132 __asm__ ( 133 #ifdef CONFIG_64 134 "bsfq %1, %0\n\t" 135 #else 136 "bsf %1, %0\n\t" 137 #endif 138 :"=r" (retval) 139 :"r" (a) 140 :"cc" 141 ); 142 143 return (int)retval; 144 } 145 /* END ASM */ 146 147 #elif defined(MASM) 148 #include <intrin.h> 149 /* 150 * Bit scan reverse. Assumptions: a != 0. 151 */ 152 static inline int __cdecl mpd_bsr(mpd_size_t a)153 mpd_bsr(mpd_size_t a) 154 { 155 unsigned long retval; 156 157 #ifdef CONFIG_64 158 _BitScanReverse64(&retval, a); 159 #else 160 _BitScanReverse(&retval, a); 161 #endif 162 163 return (int)retval; 164 } 165 166 /* 167 * Bit scan forward. Assumptions: a != 0. 168 */ 169 static inline int __cdecl mpd_bsf(mpd_size_t a)170 mpd_bsf(mpd_size_t a) 171 { 172 unsigned long retval; 173 174 #ifdef CONFIG_64 175 _BitScanForward64(&retval, a); 176 #else 177 _BitScanForward(&retval, a); 178 #endif 179 180 return (int)retval; 181 } 182 /* END MASM (_MSC_VER) */ 183 #else 184 #error "missing preprocessor definitions" 185 #endif /* BSR/BSF */ 186 187 188 #endif /* LIBMPDEC_BITS_H_ */ 189