51 lines
1.1 KiB
C
51 lines
1.1 KiB
C
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/* Copyright (C) 2001-2007 Peter Selinger.
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This file is part of Potrace. It is free software and it is covered
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by the GNU General Public License. See the file COPYING for details. */
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/* $Id: bitops.h 147 2007-04-09 00:44:09Z selinger $ */
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/* bits.h: this file defines some macros for bit manipulations. We
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provide a generic implementation */
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/* lobit: return the position of the rightmost "1" bit of an int, or
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32 if none. hibit: return 1 + the position of the leftmost "1" bit
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of an int, or 0 if none. Note: these functions work on 32-bit
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integers. */
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#ifndef BITOPS_H
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#define BITOPS_H
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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/* generic macros */
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static inline unsigned int lobit(unsigned int x) {
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unsigned int res = 32;
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while (x & 0xffffff) {
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x <<= 8;
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res -= 8;
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}
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while (x) {
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x <<= 1;
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res -= 1;
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}
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return res;
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}
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static inline unsigned int hibit(unsigned int x) {
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unsigned int res = 0;
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while (x > 0xff) {
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x >>= 8;
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res += 8;
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}
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while (x) {
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x >>= 1;
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res += 1;
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}
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return res;
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}
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#endif /* BITOPS_H */
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