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/*
* 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/>.
*
*
*/
#ifndef __COGL_UTIL_H
#define __COGL_UTIL_H
#include <glib.h>
#include <math.h>
int
cogl_util_next_p2 (int a);
/* The signbit macro is defined by ISO C99 so it should be available,
however if it's not we can fallback to an evil hack */
#ifdef signbit
#define cogl_util_float_signbit(x) signbit(x)
#else
/* This trick was stolen from here:
http://lists.boost.org/Archives/boost/2006/08/108731.php
It xors the integer reinterpretations of -1.0f and 1.0f. In theory
they should only differ by the signbit so that gives a mask for the
sign which we can just test against the value */
static inline gboolean
cogl_util_float_signbit (float x)
{
static const union { float f; guint32 i; } negative_one = { -1.0f };
static const union { float f; guint32 i; } positive_one = { +1.0f };
union { float f; guint32 i; } value = { x };
return !!((negative_one.i ^ positive_one.i) & value.i);
}
#endif
/* This is a replacement for the nearbyint function which always
rounds to the nearest integer. nearbyint is apparently a C99
function so it might not always be available but also it seems in
glibc it is defined as a function call so this macro could end up
faster anyway. We can't just add 0.5f because it will break for
negative numbers. */
#define COGL_UTIL_NEARBYINT(x) ((int) ((x) < 0.0f ? (x) - 0.5f : (x) + 0.5f))
#endif /* __COGL_UTIL_H */
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