Miscellaneous
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<?php
/* Functions for manipulating BITFIELDS
*
* init_bit( bitfield );
* query_bit( bitfield, bit );
* set_bit( bitfield, bit );
* remove_bit( bitfield, bit );
* toggle_bit( bitfield, bit );
*
*/
/* Some handy bitvalues, easy to remember */
define( "BIT_0", 0 );
define( "BIT_1", 1 );
define( "BIT_2", 2 );
define( "BIT_3", 4 );
define( "BIT_4", 8 );
define( "BIT_5", 16 );
define( "BIT_6", 32 );
define( "BIT_7", 64 );
define( "BIT_8", 128 );
define( "BIT_9", 256 );
define( "BIT_10", 512 );
define( "BIT_11", 1024 );
define( "BIT_12", 2048 );
define( "BIT_13", 4096 );
define( "BIT_14", 8192 );
define( "BIT_15", 16384 );
define( "BIT_16", 32768 );
define( "BIT_17", 65536 );
define( "BIT_18", 131072 );
define( "BIT_19", 262144 );
define( "BIT_20", 524288 );
define( "BIT_21", 1048576 );
define( "BIT_22", 2097152 );
define( "BIT_23", 4194304 );
define( "BIT_24", 8388608 );
define( "BIT_25", 16777216 );
define( "BIT_26", 33554432 );
define( "BIT_27", 67108864 );
define( "BIT_28", 134217728 );
define( "BIT_29", 268435456 );
define( "BIT_30", 536870912 );
define( "BIT_31", 1073741824 );
/* Because of a bug in PHP we need this init function,
* it's a workaround for the bug. If you want to know if
* this bug has been fixed, check bugs.php.net, bugid: 3176
* So, best is to use this simple init every time you
* create a new bitfield variable.
*/
function init_bit( &$bitfield )
{
$bitfield = ($bitfield | 0);
}
/* Return true or false, depending on if the bit is set */
function query_bit( $bitfield, $bit )
{
return ( $bitfield & $bit );
}
/* Force a specific bit(pattern) to ON */
function set_bit( &$bitfield, $bit )
{
$bitfield |= $bit;
}
/* Force a specific bit(pattern) to be OFF */
function remove_bit( &$bitfield, $bit )
{
$bitfield &= ~$bit;
}
/* Toggle a bit(pattern), so bits that are on are turned off, and bits that are off are turned on. */
function toggle_bit( &$bitfield, $bit )
{
$bitfield ^= $bit;
}
?>
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Usage Example
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$bitfield = 0;
bit_init( $bitfield );
set_bit( $bitfield, BIT_10 )
toggle_bit( $bitfield, BIT_11 )
query_bit( $bitfield, BIT_10) -> true
query_bit( $bitfield, BIT_11) -> true
query_bit( $bitfield, BIT_5 ) -> false
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