note 90142 added to function.pack
| From: | Coder at osu1 dot php dot net | Date: | Tue, 07 Apr 2009 23:54:15 +0000 |
| Subject: | note 90142 added to function.pack | ||
| Groups: | php.notes | ||
| Request: | Send a blank email to php-notes+get-152932@lists.php.net to get a copy of this message | ||
These two functions allow conversion between binary string and signed integer with possibility to
give the bit length.
Usage:
echo si2bin(-10, 32);
11111111111111111111111111110110
echo si2bin(10, 32);
00000000000000000000000000001010
echo bin2si("11111111111111111111111111110110", 32);
-10
echo bin2si("00000000000000000000000000001010", 32);
10
// signed integer to binary
function si2bin($si, $bits=32)
{
if ($si >= -pow(2,$bits-1) and $si <= pow(2,$bits-1) )
{
if ($si >= 0) // positive or zero
{
$bin = base_convert($si,10,2);
// pad to $bits bit
$bin_length = strlen($bin);
if ($bin_length < $bits) $bin = str_repeat ( "0", $bits-$bin_length).$bin;
}
else // negative
{
$si = -$si-pow(2,$bits);
$bin = base_convert($si,10,2);
$bin_length = strlen($bin);
if ($bin_length > $bits) $bin = str_repeat ( "1", $bits-$bin_length).$bin;
}
return $bin;
}
}
// binary to signed integer
function bin2si($bin,$bits=32)
{
if (strlen($bin)==$bits)
{
if (substr($bin,0,1) == 0) // positive or zero
{
$si = base_convert($bin,2,10);
}
else // negative
{
$si = base_convert($bin,2,10);
$si = -(pow(2,$bits)-$si);
}
return $si;
}
}
----
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----
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