Just a couple of comments about those 0xffff.. and 1111111111 in my post. (By the way, i haven't looked to closely on speed even if the OP asked for that, i was unsure on how he was coding his numbers).
[EMAIL PROTECTED] (Rolf Østvik) wrote in news:[EMAIL PROTECTED]: > [EMAIL PROTECTED] (René Fournier) wrote in > news:[EMAIL PROTECTED]: > >> I need to convert a binary number of arbitrary length to a signed >> integer. > > If you on the other hand know that the string should represent an 8 > bit in two's complement then this could work: > > function bin2int ($bin) { > $a = bindec($bin); > > $val = ($a | 0x80) ? (0xffffff00 | $a) : $a; if the input is a 8 bit signed binary string then bit 7 determine the sign. 0xffffff00 will then make this to an 32 signed integer > > return $val; > } > > function bin2int ($bin) { > if (substr($bin,0,1) == 1) { > // NEGATIVE > $val = bindec(substr("11111111111111111111111111111111" > .$bin,-32)); bindec returns a 32 bit signed integer, i just make sure that the leftmost bits in the 32 character long string are 1 if the leftmost bit in the original string is 1. > } else { > // POSITIVE > $val = bindec($bin); > } > return $val; > } > -- Rolf -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
