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/******************************************************************************
* $Id$
*
* Project: MapServer
* Purpose: Implementation of bit array functions.
* Author: Steve Lime and the MapServer team.
*
* Notes: Derived from code placed in the public domain by Bob Stout, for more
* information see http://c.snippets.org/snip_lister.php?fname=bitarray.c.
*
******************************************************************************
* Copyright (c) 1996-2005 Regents of the University of Minnesota.
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies of this Software or works derived from this Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
****************************************************************************/
#include "mapserver.h"
#include <limits.h>
/*
* Hardcoded size of our bit array.
* See function msGetNextBit for another hardcoded value.
*/
/* #define msGetBit(array, index) (*((array) + (index)/MS_ARRAY_BIT) & ( 1 << ((index) % MS_ARRAY_BIT))) */
size_t msGetBitArraySize(int numbits)
{
return((numbits + MS_ARRAY_BIT - 1) / MS_ARRAY_BIT);
}
ms_bitarray msAllocBitArray(int numbits)
{
ms_bitarray array = calloc((numbits + MS_ARRAY_BIT - 1) / MS_ARRAY_BIT, MS_ARRAY_BIT);
return(array);
}
int msGetBit(ms_bitarray array, int index)
{
array += index / MS_ARRAY_BIT;
return (*array & (1 << (index % MS_ARRAY_BIT))) != 0; /* 0 or 1 */
}
/*
** msGetNextBit( status, start, size)
**
** Quickly find the next bit set. If start == 0 and 0 is set, will return 0.
** If hits end of bitmap without finding set bit, will return -1.
**
*/
int msGetNextBit(ms_bitarray array, int i, int size)
{
register ms_uint32 b;
while(i < size) {
b = *(array + (i/MS_ARRAY_BIT));
if( b && (b >> (i % MS_ARRAY_BIT)) ) {
/* There is something in this byte */
/* And it is not to the right of us */
if( b & ( 1 << (i % MS_ARRAY_BIT)) ) {
/* There is something at this bit! */
return i;
} else {
i++;
}
} else {
/* Nothing in this byte, move to start of next byte */
i += MS_ARRAY_BIT - (i % MS_ARRAY_BIT);
}
}
/* Got to the last byte with no hits! */
return -1;
}
void msSetBit(ms_bitarray array, int index, int value)
{
array += index / MS_ARRAY_BIT;
if (value)
*array |= 1 << (index % MS_ARRAY_BIT); /* set bit */
else
*array &= ~(1 << (index % MS_ARRAY_BIT)); /* clear bit */
}
void msSetAllBits(ms_bitarray array, int numbits, int value)
{
if (value)
memset(array, 0xff, ((numbits + 7) / 8) ); /* set bit */
else
memset(array, 0x0, ((numbits + 7) / 8) ); /* clear bit */
}
void msFlipBit(ms_bitarray array, int index)
{
array += index / MS_ARRAY_BIT;
*array ^= 1 << (index % MS_ARRAY_BIT); /* flip bit */
}
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