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