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189 lines
4.3 KiB
C
189 lines
4.3 KiB
C
/*
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* Copyright (c) 2008-2020 Stefan Krah. All rights reserved.
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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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*
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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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*
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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 AUTHOR AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef LIBMPDEC_BITS_H_
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#define LIBMPDEC_BITS_H_
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#include "mpdecimal.h"
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/* Check if n is a power of 2. */
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static inline int
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ispower2(mpd_size_t n)
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{
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return n != 0 && (n & (n-1)) == 0;
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}
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#if defined(ANSI)
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/*
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* Return the most significant bit position of n from 0 to 31 (63).
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* Assumptions: n != 0.
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*/
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static inline int
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mpd_bsr(mpd_size_t n)
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{
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int pos = 0;
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mpd_size_t tmp;
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#ifdef CONFIG_64
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tmp = n >> 32;
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if (tmp != 0) { n = tmp; pos += 32; }
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#endif
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tmp = n >> 16;
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if (tmp != 0) { n = tmp; pos += 16; }
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tmp = n >> 8;
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if (tmp != 0) { n = tmp; pos += 8; }
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tmp = n >> 4;
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if (tmp != 0) { n = tmp; pos += 4; }
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tmp = n >> 2;
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if (tmp != 0) { n = tmp; pos += 2; }
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tmp = n >> 1;
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if (tmp != 0) { n = tmp; pos += 1; }
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return pos + (int)n - 1;
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}
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/*
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* Return the least significant bit position of n from 0 to 31 (63).
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* Assumptions: n != 0.
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*/
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static inline int
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mpd_bsf(mpd_size_t n)
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{
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int pos;
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#ifdef CONFIG_64
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pos = 63;
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if (n & 0x00000000FFFFFFFFULL) { pos -= 32; } else { n >>= 32; }
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if (n & 0x000000000000FFFFULL) { pos -= 16; } else { n >>= 16; }
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if (n & 0x00000000000000FFULL) { pos -= 8; } else { n >>= 8; }
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if (n & 0x000000000000000FULL) { pos -= 4; } else { n >>= 4; }
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if (n & 0x0000000000000003ULL) { pos -= 2; } else { n >>= 2; }
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if (n & 0x0000000000000001ULL) { pos -= 1; }
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#else
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pos = 31;
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if (n & 0x000000000000FFFFUL) { pos -= 16; } else { n >>= 16; }
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if (n & 0x00000000000000FFUL) { pos -= 8; } else { n >>= 8; }
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if (n & 0x000000000000000FUL) { pos -= 4; } else { n >>= 4; }
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if (n & 0x0000000000000003UL) { pos -= 2; } else { n >>= 2; }
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if (n & 0x0000000000000001UL) { pos -= 1; }
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#endif
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return pos;
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}
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/* END ANSI */
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#elif defined(ASM)
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/*
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* Bit scan reverse. Assumptions: a != 0.
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*/
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static inline int
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mpd_bsr(mpd_size_t a)
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{
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mpd_size_t retval;
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__asm__ (
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#ifdef CONFIG_64
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"bsrq %1, %0\n\t"
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#else
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"bsr %1, %0\n\t"
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#endif
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:"=r" (retval)
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:"r" (a)
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:"cc"
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);
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return (int)retval;
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}
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/*
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* Bit scan forward. Assumptions: a != 0.
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*/
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static inline int
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mpd_bsf(mpd_size_t a)
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{
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mpd_size_t retval;
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__asm__ (
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#ifdef CONFIG_64
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"bsfq %1, %0\n\t"
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#else
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"bsf %1, %0\n\t"
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#endif
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:"=r" (retval)
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:"r" (a)
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:"cc"
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);
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return (int)retval;
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}
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/* END ASM */
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#elif defined(MASM)
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#include <intrin.h>
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/*
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* Bit scan reverse. Assumptions: a != 0.
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*/
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static inline int __cdecl
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mpd_bsr(mpd_size_t a)
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{
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unsigned long retval;
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#ifdef CONFIG_64
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_BitScanReverse64(&retval, a);
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#else
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_BitScanReverse(&retval, a);
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#endif
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return (int)retval;
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}
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/*
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* Bit scan forward. Assumptions: a != 0.
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*/
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static inline int __cdecl
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mpd_bsf(mpd_size_t a)
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{
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unsigned long retval;
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#ifdef CONFIG_64
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_BitScanForward64(&retval, a);
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#else
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_BitScanForward(&retval, a);
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#endif
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return (int)retval;
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}
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/* END MASM (_MSC_VER) */
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#else
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#error "missing preprocessor definitions"
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#endif /* BSR/BSF */
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#endif /* LIBMPDEC_BITS_H_ */
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