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d706991579
This adds some macros to iterate over all the bits set in an array of flags. The macros are a bit awkward because it tries to avoid using a callback pointer so that the code is inlined. cogl_bitmask is now using these macros as well so that the logic can be shared. Reviewed-by: Robert Bragg <robert@linux.intel.com>
121 lines
4.3 KiB
C
121 lines
4.3 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) 2011 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, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*
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* Authors:
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* Neil Roberts <neil@linux.intel.com>
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*/
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#ifndef __COGL_FLAGS_H
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#define __COGL_FLAGS_H
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#include <glib.h>
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#include "cogl-util.h"
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G_BEGIN_DECLS
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/* These are macros used to implement a fixed-size array of bits. This
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should be used instead of CoglBitmask when the maximum bit number
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that will be set is known at compile time, for example when setting
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for recording a set of known available features */
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/* The bits are stored in an array of unsigned longs. To use these
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macros, you would typically have an enum defining the available
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bits with an extra last enum to define the maximum value. Then to
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store the flags you would declare an array of unsigned longs sized
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using COGL_FLAGS_N_LONGS_FOR_SIZE, eg:
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typedef enum { FEATURE_A, FEATURE_B, FEATURE_C, N_FEATURES } Features;
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unsigned long feature_flags[COGL_FLAGS_N_LONGS_FOR_SIZE (N_FEATURES)];
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*/
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#define COGL_FLAGS_N_LONGS_FOR_SIZE(size) \
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(((size) + \
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(sizeof (unsigned long) * 8 - 1)) \
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/ (sizeof (unsigned long) * 8))
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/* @flag is expected to be constant so these should result in a
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constant expression. This means that setting a flag is equivalent
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to just setting in a bit in a global variable at a known
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location */
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#define COGL_FLAGS_GET_INDEX(flag) \
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((flag) / (sizeof (unsigned long) * 8))
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#define COGL_FLAGS_GET_MASK(flag) \
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(1UL << ((unsigned long) (flag) & \
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(sizeof (unsigned long) * 8 - 1)))
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#define COGL_FLAGS_GET(array, flag) \
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(!!((array)[COGL_FLAGS_GET_INDEX (flag)] & \
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COGL_FLAGS_GET_MASK (flag)))
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/* The expectation here is that @value will be constant so the if
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statement will be optimised out */
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#define COGL_FLAGS_SET(array, flag, value) \
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G_STMT_START { \
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if (value) \
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((array)[COGL_FLAGS_GET_INDEX (flag)] |= \
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COGL_FLAGS_GET_MASK (flag)); \
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else \
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((array)[COGL_FLAGS_GET_INDEX (flag)] &= \
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~COGL_FLAGS_GET_MASK (flag)); \
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} G_STMT_END
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/* Macros to help iterate an array of flags. It should be used like
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* this:
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*
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* int n_longs = COGL_FLAGS_N_LONGS_FOR_SIZE (...);
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* unsigned long flags[n_longs];
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* int bit_num;
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*
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* COGL_FLAGS_FOREACH_START (flags, n_longs, bit_num)
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* {
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* do_something_with_the_bit (bit_num);
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* }
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* COGL_FLAGS_FOREACH_END;
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*/
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#define COGL_FLAGS_FOREACH_START(array, n_longs, bit) \
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G_STMT_START { \
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const unsigned long *_p = (array); \
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int _n_longs = (n_longs); \
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int _i; \
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\
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for (_i = 0; _i < _n_longs; _i++) \
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{ \
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unsigned long _mask = *(_p++); \
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\
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(bit) = _i * sizeof (unsigned long) * 8 - 1; \
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\
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while (_mask) \
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{ \
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int _next_bit = _cogl_util_ffsl (_mask); \
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(bit) += _next_bit; \
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_mask >>= _next_bit;
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#define COGL_FLAGS_FOREACH_END \
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} } } G_STMT_END
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G_END_DECLS
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#endif /* __COGL_FLAGS_H */
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