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/*
* Copyright (c) 2008-2020 Stefan Krah. All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "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 THE AUTHOR OR CONTRIBUTORS 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.
*/
#ifndef LIBMPDEC_BITS_H_
#define LIBMPDEC_BITS_H_
#include "mpdecimal.h"
/* Check if n is a power of 2. */
static inline int
ispower2(mpd_size_t n)
{
return n != 0 && (n & (n-1)) == 0;
}
#if defined(ANSI)
/*
* Return the most significant bit position of n from 0 to 31 (63).
* Assumptions: n != 0.
*/
static inline int
mpd_bsr(mpd_size_t n)
{
int pos = 0;
mpd_size_t tmp;
#ifdef CONFIG_64
tmp = n >> 32;
if (tmp != 0) { n = tmp; pos += 32; }
#endif
tmp = n >> 16;
if (tmp != 0) { n = tmp; pos += 16; }
tmp = n >> 8;
if (tmp != 0) { n = tmp; pos += 8; }
tmp = n >> 4;
if (tmp != 0) { n = tmp; pos += 4; }
tmp = n >> 2;
if (tmp != 0) { n = tmp; pos += 2; }
tmp = n >> 1;
if (tmp != 0) { n = tmp; pos += 1; }
return pos + (int)n - 1;
}
/*
* Return the least significant bit position of n from 0 to 31 (63).
* Assumptions: n != 0.
*/
static inline int
mpd_bsf(mpd_size_t n)
{
int pos;
#ifdef CONFIG_64
pos = 63;
if (n & 0x00000000FFFFFFFFULL) { pos -= 32; } else { n >>= 32; }
if (n & 0x000000000000FFFFULL) { pos -= 16; } else { n >>= 16; }
if (n & 0x00000000000000FFULL) { pos -= 8; } else { n >>= 8; }
if (n & 0x000000000000000FULL) { pos -= 4; } else { n >>= 4; }
if (n & 0x0000000000000003ULL) { pos -= 2; } else { n >>= 2; }
if (n & 0x0000000000000001ULL) { pos -= 1; }
#else
pos = 31;
if (n & 0x000000000000FFFFUL) { pos -= 16; } else { n >>= 16; }
if (n & 0x00000000000000FFUL) { pos -= 8; } else { n >>= 8; }
if (n & 0x000000000000000FUL) { pos -= 4; } else { n >>= 4; }
if (n & 0x0000000000000003UL) { pos -= 2; } else { n >>= 2; }
if (n & 0x0000000000000001UL) { pos -= 1; }
#endif
return pos;
}
/* END ANSI */
#elif defined(ASM)
/*
* Bit scan reverse. Assumptions: a != 0.
*/
static inline int
mpd_bsr(mpd_size_t a)
{
mpd_size_t retval;
__asm__ (
#ifdef CONFIG_64
"bsrq %1, %0\n\t"
#else
"bsr %1, %0\n\t"
#endif
:"=r" (retval)
:"r" (a)
:"cc"
);
return (int)retval;
}
/*
* Bit scan forward. Assumptions: a != 0.
*/
static inline int
mpd_bsf(mpd_size_t a)
{
mpd_size_t retval;
__asm__ (
#ifdef CONFIG_64
"bsfq %1, %0\n\t"
#else
"bsf %1, %0\n\t"
#endif
:"=r" (retval)
:"r" (a)
:"cc"
);
return (int)retval;
}
/* END ASM */
#elif defined(MASM)
#include <intrin.h>
/*
* Bit scan reverse. Assumptions: a != 0.
*/
static inline int __cdecl
mpd_bsr(mpd_size_t a)
{
unsigned long retval;
#ifdef CONFIG_64
_BitScanReverse64(&retval, a);
#else
_BitScanReverse(&retval, a);
#endif
return (int)retval;
}
/*
* Bit scan forward. Assumptions: a != 0.
*/
static inline int __cdecl
mpd_bsf(mpd_size_t a)
{
unsigned long retval;
#ifdef CONFIG_64
_BitScanForward64(&retval, a);
#else
_BitScanForward(&retval, a);
#endif
return (int)retval;
}
/* END MASM (_MSC_VER) */
#else
#error "missing preprocessor definitions"
#endif /* BSR/BSF */
#endif /* LIBMPDEC_BITS_H_ */
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