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583d5cc79f
cogl_util_next_p2 is declared in cogl-util.h which is a private header so it shouldn't be possible for an application to use it. It's probably not a function we'd like to export from Cogl so it seems better to keep it private. This patch renames it to _cogl_util_next_p2 so that it won't be exported from the shared library. The documentation for the function is also slightly wrong because it stated that the function returned the next power greater than 'a'. However the code would actually return 'a' if it's already a power of two. I think the actual behaviour is more useful so this patch changes the documentation rather than the code.
72 lines
2.3 KiB
C
72 lines
2.3 KiB
C
/*
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* Cogl
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*
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* An object oriented GL/GLES Abstraction/Utility Layer
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*
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* Copyright (C) 2007,2008,2009,2010 Intel Corporation.
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*
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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 of the License, or (at your option) any later version.
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*
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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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*
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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, see <http://www.gnu.org/licenses/>.
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*
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*
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*/
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#ifndef __COGL_UTIL_H
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#define __COGL_UTIL_H
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#include <glib.h>
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#include <math.h>
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int
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_cogl_util_next_p2 (int a);
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/* The signbit macro is defined by ISO C99 so it should be available,
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however if it's not we can fallback to an evil hack */
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#ifdef signbit
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#define cogl_util_float_signbit(x) signbit(x)
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#else
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/* This trick was stolen from here:
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http://lists.boost.org/Archives/boost/2006/08/108731.php
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It xors the integer reinterpretations of -1.0f and 1.0f. In theory
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they should only differ by the signbit so that gives a mask for the
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sign which we can just test against the value */
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static inline gboolean
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cogl_util_float_signbit (float x)
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{
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static const union { float f; guint32 i; } negative_one = { -1.0f };
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static const union { float f; guint32 i; } positive_one = { +1.0f };
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union { float f; guint32 i; } value = { x };
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return !!((negative_one.i ^ positive_one.i) & value.i);
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}
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#endif
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/* This is a replacement for the nearbyint function which always
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rounds to the nearest integer. nearbyint is apparently a C99
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function so it might not always be available but also it seems in
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glibc it is defined as a function call so this macro could end up
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faster anyway. We can't just add 0.5f because it will break for
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negative numbers. */
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#define COGL_UTIL_NEARBYINT(x) ((int) ((x) < 0.0f ? (x) - 0.5f : (x) + 0.5f))
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/* Returns whether the given integer is a power of two */
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static inline gboolean
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_cogl_util_is_pot (unsigned int num)
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{
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/* Make sure there is only one bit set */
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return (num & (num - 1)) == 0;
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}
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#endif /* __COGL_UTIL_H */
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