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/* vim:ts=8:sts=4:sw=4:noai:noexpandtab
*
* Shared math routines.
*
* Copyright (c) 2006-2009 Miru Limited.
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#if !defined (__PGM_IMPL_FRAMEWORK_H_INSIDE__) && !defined (PGM_COMPILATION)
# error "Only <framework.h> can be included directly."
#endif
#ifndef __PGM_IMPL_MATH_H__
#define __PGM_IMPL_MATH_H__
#include <pgm/types.h>
PGM_BEGIN_DECLS
/* fast log base 2 of power of 2
*/
static inline unsigned pgm_power2_log2 (unsigned) PGM_GNUC_CONST;
static inline
unsigned
pgm_power2_log2 (
unsigned v
)
{
static const unsigned int b[] = { 0xAAAAAAAA, 0xCCCCCCCC, 0xF0F0F0F0, 0xFF00FF00, 0xFFFF0000 };
unsigned int r = (v & b[0]) != 0;
for (unsigned i = 4; i > 0; i--) {
r |= ((v & b[i]) != 0) << i;
}
return r;
}
/* nearest power of 2
*/
static inline size_t pgm_nearest_power (size_t, size_t) PGM_GNUC_CONST;
static inline
size_t
pgm_nearest_power (
size_t b,
size_t v
)
{
if (v > (SIZE_MAX/2))
return SIZE_MAX;
while (b < v)
b <<= 1;
return b;
}
unsigned pgm_spaced_primes_closest (unsigned) PGM_GNUC_PURE;
PGM_END_DECLS
#endif /* __PGM_IMPL_MATH_H__ */
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