<?php
$a = 65;
$b = ~$a + 1;   // get twos complement
printf("%d\n0x%x\n\n",$b,$b);

$b = -(pow(2,32) - 0xffffffbf);
var_dump($b);
printf("%d\n0x%x\n\n",$b,$b);
            
$c = base_convert($b,10,2);
echo $c,"\n";
$i = intval($c,2);
echo $i;

-65
0xffffffbf

float(-65)
-65
0xffffffbf

1000001
65