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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 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, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
* Authors:
* Neil Roberts <neil@linux.intel.com>
*/
#ifndef __COGL_BITMASK_H
#define __COGL_BITMASK_H
#include <glib.h>
G_BEGIN_DECLS
/*
* CoglBitmask implements a growable array of bits. A CoglBitmask can
* be allocated on the stack but it must be initialised with
* _cogl_bitmask_init() before use and then destroyed with
* _cogl_bitmask_destroy(). A CoglBitmask will try to avoid allocating
* any memory unless more than 31 bits are needed.
*
* Internally a CoglBitmask is a pointer. If the least significant bit
* of the pointer is 1 then the rest of the bits are directly used as
* part of the bitmask, otherwise it is a pointer to a GArray of
* unsigned ints. This relies on the fact the g_malloc will return a
* pointer aligned to at least two bytes (so that the least
* significant bit of the address is always 0)
*
* If the maximum possible bit number in the set is known at compile
* time, it may make more sense to use the macros in cogl-flags.h
* instead of this type.
*/
typedef struct _CoglBitmaskImaginaryType *CoglBitmask;
/* Internal helper macro to determine whether this bitmask has a
GArray allocated or whether the pointer is just used directly */
#define _cogl_bitmask_has_array(bitmask) \
(!(GPOINTER_TO_UINT (*bitmask) & 1))
/* Number of bits we can use before needing to allocate an array */
#define COGL_BITMASK_MAX_DIRECT_BITS (sizeof (unsigned int) * 8 - 1)
/*
* _cogl_bitmask_init:
* @bitmask: A pointer to a bitmask
*
* Initialises the cogl bitmask. This must be called before any other
* bitmask functions are called. Initially all of the values are
* zero
*/
/* Set the last significant bit to mark that no array has been
allocated yet */
#define _cogl_bitmask_init(bitmask) \
G_STMT_START { *(bitmask) = GUINT_TO_POINTER (1); } G_STMT_END
gboolean
_cogl_bitmask_get_from_array (const CoglBitmask *bitmask,
unsigned int bit_num);
void
_cogl_bitmask_set_in_array (CoglBitmask *bitmask,
unsigned int bit_num,
gboolean value);
void
_cogl_bitmask_set_range_in_array (CoglBitmask *bitmask,
unsigned int n_bits,
gboolean value);
void
_cogl_bitmask_clear_all_in_array (CoglBitmask *bitmask);
/*
* cogl_bitmask_set_bits:
* @dst: The bitmask to modify
* @src: The bitmask to copy bits from
*
* This makes sure that all of the bits that are set in @src are also
* set in @dst. Any unset bits in @src are left alone in @dst.
*/
void
_cogl_bitmask_set_bits (CoglBitmask *dst,
const CoglBitmask *src);
/*
* cogl_bitmask_xor_bits:
* @dst: The bitmask to modify
* @src: The bitmask to copy bits from
*
* For every bit that is set in src, the corresponding bit in dst is
* inverted.
*/
void
_cogl_bitmask_xor_bits (CoglBitmask *dst,
const CoglBitmask *src);
typedef void (* CoglBitmaskForeachFunc) (int bit_num, gpointer user_data);
/*
* cogl_bitmask_foreach:
* @bitmask: A pointer to a bitmask
* @func: A callback function
* @user_data: A pointer to pass to the callback
*
* This calls @func for each bit that is set in @bitmask.
*/
void
_cogl_bitmask_foreach (const CoglBitmask *bitmask,
CoglBitmaskForeachFunc func,
gpointer user_data);
/*
* _cogl_bitmask_get:
* @bitmask: A pointer to a bitmask
* @bit_num: A bit number
*
* Return value: whether bit number @bit_num is set in @bitmask
*/
static inline gboolean
_cogl_bitmask_get (const CoglBitmask *bitmask, unsigned int bit_num)
{
if (_cogl_bitmask_has_array (bitmask))
return _cogl_bitmask_get_from_array (bitmask, bit_num);
else if (bit_num >= COGL_BITMASK_MAX_DIRECT_BITS)
return FALSE;
else
return !!(GPOINTER_TO_UINT (*bitmask) & (1 << (bit_num + 1)));
}
/*
* _cogl_bitmask_set:
* @bitmask: A pointer to a bitmask
* @bit_num: A bit number
* @value: The new value
*
* Sets or resets a bit number @bit_num in @bitmask according to @value.
*/
static inline void
_cogl_bitmask_set (CoglBitmask *bitmask, unsigned int bit_num, gboolean value)
{
if (_cogl_bitmask_has_array (bitmask) ||
bit_num >= COGL_BITMASK_MAX_DIRECT_BITS)
_cogl_bitmask_set_in_array (bitmask, bit_num, value);
else if (value)
*bitmask = GUINT_TO_POINTER (GPOINTER_TO_UINT (*bitmask) |
(1 << (bit_num + 1)));
else
*bitmask = GUINT_TO_POINTER (GPOINTER_TO_UINT (*bitmask) &
~(1 << (bit_num + 1)));
}
/*
* _cogl_bitmask_set_range:
* @bitmask: A pointer to a bitmask
* @n_bits: The number of bits to set
* @value: The value to set
*
* Sets the first @n_bits in @bitmask to @value.
*/
static inline void
_cogl_bitmask_set_range (CoglBitmask *bitmask,
unsigned int n_bits,
gboolean value)
{
if (_cogl_bitmask_has_array (bitmask) ||
n_bits > COGL_BITMASK_MAX_DIRECT_BITS)
_cogl_bitmask_set_range_in_array (bitmask, n_bits, value);
else if (value)
*bitmask = GUINT_TO_POINTER (GPOINTER_TO_UINT (*bitmask) |
~(~(unsigned int) 1 << n_bits));
else
*bitmask = GUINT_TO_POINTER (GPOINTER_TO_UINT (*bitmask) &
((~(unsigned int) 1 << n_bits) | 1));
}
/*
* _cogl_bitmask_destroy:
* @bitmask: A pointer to a bitmask
*
* Destroys any resources allocated by the bitmask
*/
static inline void
_cogl_bitmask_destroy (CoglBitmask *bitmask)
{
if (_cogl_bitmask_has_array (bitmask))
g_array_free ((GArray *) *bitmask, TRUE);
}
/*
* _cogl_bitmask_clear_all:
* @bitmask: A pointer to a bitmask
*
* Clears all the bits in a bitmask without destroying any resources.
*/
static inline void
_cogl_bitmask_clear_all (CoglBitmask *bitmask)
{
if (_cogl_bitmask_has_array (bitmask))
_cogl_bitmask_clear_all_in_array (bitmask);
else
*bitmask = GUINT_TO_POINTER (1);
}
G_END_DECLS
#endif /* __COGL_BITMASK_H */
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