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/* -*- Mode: C; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
Copyright (C) 2009 Red Hat, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef BITOPS_H
#define BITOPS_H
#include <spice/macros.h>
#ifdef __cplusplus
extern "C" {
#endif
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
static inline int spice_bit_find_msb(unsigned int val)
{
int ret;
asm ("bsrl %1,%0\n\t"
"jnz 1f\n\t"
"movl $-1,%0\n"
"1:"
: "=r"(ret) : "r"(val));
return ret + 1;
}
#elif defined(WIN32) && !defined(_WIN64)
static INLINE int spice_bit_find_msb(uint32_t val)
{
uint32_t r;
__asm {
bsr eax, val
jnz found
mov eax, -1
found:
mov r, eax
}
return r + 1;
}
#else
static INLINE int spice_bit_find_msb(unsigned int val)
{
signed char index = 31;
if(val == 0) {
return 0;
}
do {
if(val & 0x80000000) {
break;
}
val <<= 1;
} while(--index >= 0);
return index+1;
}
#endif
static INLINE int spice_bit_next_pow2(unsigned int val)
{
if ((val & (val - 1)) == 0) {
return val;
}
return 1 << spice_bit_find_msb(val);
}
#ifdef __cplusplus
}
#endif
#endif
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