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127 lines
4.9 KiB
C
127 lines
4.9 KiB
C
/*
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* Cogl
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*
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* A Low Level GPU Graphics and Utilities API
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*
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* Copyright (C) 2011 Intel Corporation.
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy,
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* modify, merge, publish, distribute, sublicense, and/or sell copies
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* of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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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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#pragma once
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#include <glib.h>
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#include "cogl/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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/* This odd two-part shift is to avoid */ \
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/* shifting by sizeof (long)*8 which has */ \
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/* undefined results according to the */ \
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/* C spec (and seems to be a no-op in */ \
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/* practice) */ \
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_mask = (_mask >> (_next_bit - 1)) >> 1; \
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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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