4fb784d111
This implements a growable array of bits called CoglBitmask. The CoglBitmask is intended to be cheap if less than 32 bits are used. If more bits are required it will allocate a GArray. The type is meant to be allocated on the stack but because it can require additional resources it also has a destroy function. http://bugzilla.openedhand.com/show_bug.cgi?id=2132
223 lines
6.6 KiB
C
223 lines
6.6 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) 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, 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_BITMASK_H
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#define __COGL_BITMASK_H
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#include <glib.h>
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G_BEGIN_DECLS
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/*
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* CoglBitmask implements a growable array of bits. A CoglBitmask can
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* be allocated on the stack but it must be initialised with
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* _cogl_bitmask_init() before use and then destroyed with
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* _cogl_bitmask_destroy(). A CoglBitmask will try to avoid allocating
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* any memory unless more than 31 bits are needed.
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*
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* Internally a CoglBitmask is a pointer. If the least significant bit
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* of the pointer is 1 then the rest of the bits are directly used as
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* part of the bitmask, otherwise it is a pointer to a GArray of
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* unsigned ints. This relies on the fact the g_malloc will return a
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* pointer aligned to at least two bytes (so that the least
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* significant bit of the address is always 0)
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*/
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typedef struct _CoglBitmaskImaginaryType *CoglBitmask;
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/* Internal helper macro to determine whether this bitmask has a
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GArray allocated or whether the pointer is just used directly */
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#define _cogl_bitmask_has_array(bitmask) \
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(!(GPOINTER_TO_UINT (*bitmask) & 1))
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/* Number of bits we can use before needing to allocate an array */
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#define COGL_BITMASK_MAX_DIRECT_BITS (sizeof (unsigned int) * 8 - 1)
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/*
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* _cogl_bitmask_init:
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* @bitmask: A pointer to a bitmask
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*
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* Initialises the cogl bitmask. This must be called before any other
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* bitmask functions are called. Initially all of the values are
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* zero
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*/
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/* Set the last significant bit to mark that no array has been
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allocated yet */
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#define _cogl_bitmask_init(bitmask) \
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G_STMT_START { *(bitmask) = GUINT_TO_POINTER (1); } G_STMT_END
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gboolean
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_cogl_bitmask_get_from_array (const CoglBitmask *bitmask,
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unsigned int bit_num);
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void
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_cogl_bitmask_set_in_array (CoglBitmask *bitmask,
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unsigned int bit_num,
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gboolean value);
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void
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_cogl_bitmask_set_range_in_array (CoglBitmask *bitmask,
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unsigned int n_bits,
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gboolean value);
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void
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_cogl_bitmask_clear_all_in_array (CoglBitmask *bitmask);
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/*
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* cogl_bitmask_set_bits:
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* @dst: The bitmask to modify
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* @src: The bitmask to copy bits from
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*
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* This makes sure that all of the bits that are set in @src are also
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* set in @dst. Any unset bits in @src are left alone in @dst.
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*/
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void
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_cogl_bitmask_set_bits (CoglBitmask *dst,
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const CoglBitmask *src);
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/*
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* cogl_bitmask_clear_bits:
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* @dst: The bitmask to modify
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* @src: The bitmask to copy bits from
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*
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* This makes sure that all of the bits that are set in @src are
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* cleared in @dst. Any unset bits in @src are left alone in @dst.
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*/
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void
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_cogl_bitmask_clear_bits (CoglBitmask *dst,
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const CoglBitmask *src);
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typedef void (* CoglBitmaskForeachFunc) (int bit_num, gpointer user_data);
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/*
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* cogl_bitmask_foreach:
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* @bitmask: A pointer to a bitmask
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* @func: A callback function
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* @user_data: A pointer to pass to the callback
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*
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* This calls @func for each bit that is set in @bitmask.
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*/
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void
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_cogl_bitmask_foreach (const CoglBitmask *bitmask,
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CoglBitmaskForeachFunc func,
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gpointer user_data);
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/*
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* _cogl_bitmask_get:
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* @bitmask: A pointer to a bitmask
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* @bit_num: A bit number
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*
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* Return value: whether bit number @bit_num is set in @bitmask
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*/
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static inline gboolean
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_cogl_bitmask_get (const CoglBitmask *bitmask, unsigned int bit_num)
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{
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if (_cogl_bitmask_has_array (bitmask))
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return _cogl_bitmask_get_from_array (bitmask, bit_num);
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else if (bit_num >= COGL_BITMASK_MAX_DIRECT_BITS)
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return FALSE;
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else
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return !!(GPOINTER_TO_UINT (*bitmask) & (1 << (bit_num + 1)));
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}
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/*
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* _cogl_bitmask_set:
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* @bitmask: A pointer to a bitmask
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* @bit_num: A bit number
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* @value: The new value
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*
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* Sets or resets a bit number @bit_num in @bitmask according to @value.
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*/
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static inline void
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_cogl_bitmask_set (CoglBitmask *bitmask, unsigned int bit_num, gboolean value)
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{
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if (_cogl_bitmask_has_array (bitmask) ||
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bit_num >= COGL_BITMASK_MAX_DIRECT_BITS)
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_cogl_bitmask_set_in_array (bitmask, bit_num, value);
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else if (value)
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*bitmask = GUINT_TO_POINTER (GPOINTER_TO_UINT (*bitmask) |
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(1 << (bit_num + 1)));
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else
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*bitmask = GUINT_TO_POINTER (GPOINTER_TO_UINT (*bitmask) &
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~(1 << (bit_num + 1)));
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}
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/*
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* _cogl_bitmask_set_range:
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* @bitmask: A pointer to a bitmask
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* @n_bits: The number of bits to set
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* @value: The value to set
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*
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* Sets the first @n_bits in @bitmask to @value.
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*/
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static inline void
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_cogl_bitmask_set_range (CoglBitmask *bitmask,
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unsigned int n_bits,
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gboolean value)
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{
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if (_cogl_bitmask_has_array (bitmask) ||
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n_bits > COGL_BITMASK_MAX_DIRECT_BITS)
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_cogl_bitmask_set_range_in_array (bitmask, n_bits, value);
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else if (value)
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*bitmask = GUINT_TO_POINTER (GPOINTER_TO_UINT (*bitmask) |
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~(~(unsigned int) 1 << n_bits));
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else
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*bitmask = GUINT_TO_POINTER (GPOINTER_TO_UINT (*bitmask) &
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((~(unsigned int) 1 << n_bits) | 1));
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}
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/*
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* _cogl_bitmask_destroy:
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* @bitmask: A pointer to a bitmask
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*
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* Destroys any resources allocated by the bitmask
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*/
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static inline void
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_cogl_bitmask_destroy (CoglBitmask *bitmask)
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{
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if (_cogl_bitmask_has_array (bitmask))
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g_array_free ((GArray *) *bitmask, TRUE);
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}
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/*
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* _cogl_bitmask_clear_all:
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* @bitmask: A pointer to a bitmask
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*
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* Clears all the bits in a bitmask without destroying any resources.
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*/
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static inline void
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_cogl_bitmask_clear_all (CoglBitmask *bitmask)
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{
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if (_cogl_bitmask_has_array (bitmask))
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_cogl_bitmask_clear_all_in_array (bitmask);
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else
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*bitmask = GUINT_TO_POINTER (1);
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}
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G_END_DECLS
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#endif /* __COGL_BITMASK_H */
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