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mutter-performance-source/cogl/cogl-util.c
Neil Roberts 037c0aa88c Move POPCOUNTL to cogl-util
This moves the POPCOUNTL macro from cogl-winsys-glx to cogl-util and
renames it to _cogl_util_popcountl so that it can be used in more
places. The fallback function for when the GCC builtin is not
available has been replaced with an 8-bit lookup table because the
HAKMEM implementation doesn't look like it would work when longs are
64-bit so it's not suitable for a general purpose function on 64-bit
architectures. Some of the pages regarding population counts seem to
suggest that using a lookup table is the fastest method anyway.

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2011-11-16 16:32:11 +00:00

122 lines
2.9 KiB
C

/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2007,2008,2009,2010 Intel Corporation.
*
* 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 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, see <http://www.gnu.org/licenses/>.
*
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "cogl-util.h"
/*
* cogl_util_next_p2:
* @a: Value to get the next power of two
*
* Calculates the next power of two greater than or equal to @a.
*
* Return value: @a if @a is already a power of two, otherwise returns
* the next nearest power of two.
*/
int
_cogl_util_next_p2 (int a)
{
int rval = 1;
while (rval < a)
rval <<= 1;
return rval;
}
unsigned int
_cogl_util_one_at_a_time_mix (unsigned int hash)
{
hash += ( hash << 3 );
hash ^= ( hash >> 11 );
hash += ( hash << 15 );
return hash;
}
/* The 'ffs' function is part of C99 so it isn't always available */
#ifndef HAVE_FFS
int
_cogl_util_ffs (int num)
{
int i = 1;
if (num == 0)
return 0;
while ((num & 1) == 0)
{
num >>= 1;
i++;
}
return i;
}
#endif /* HAVE_FFS */
/* The 'ffsl' is non-standard but when building with GCC we'll use its
builtin instead */
#ifndef COGL_UTIL_HAVE_BUILTIN_FFSL
int
_cogl_util_ffsl_wrapper (long int num)
{
int i = 1;
if (num == 0)
return 0;
while ((num & 1) == 0)
{
num >>= 1;
i++;
}
return i;
}
#endif /* COGL_UTIL_HAVE_BUILTIN_FFSL */
#ifndef COGL_UTIL_HAVE_BUILTIN_POPCOUNTL
const unsigned char
_cogl_util_popcount_table[256] =
{
0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3, 2, 3, 3, 4,
2, 3, 3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4,
2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6,
4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4, 3, 4, 4, 5,
3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6,
4, 5, 5, 6, 5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
};
#endif /* COGL_UTIL_HAVE_BUILTIN_POPCOUNTL */