I'm sure there was a page showing how to count the number of binary 1s in a 32bit number.
Can anyone point me to it please or provide an algorithm. Thanks
Can anyone point me to it please or provide an algorithm. Thanks
This macro counts the no of 1's in esi I believe, someone posted it here once.
POPCOUNT1 MACRO
mov edx,esi
shr edx,1
and edx,055555555h ; (n >> 1) & 0x55555555
sub esi,edx ; n - ((n >> 1) & 0x55555555)
mov edx,esi
shr edx,2 ; n >> 2
and esi,033333333h ; n & 0x33333333
and edx,033333333h ; (n >> 2) & 0x33333333
add esi,edx ; n = (n & 0x33333333) + ((n >> 2) & 0x33333333)
mov edx,esi
shr edx,4 ; n >> 4
add edx,esi ; n + (n >> 4)
and edx,00F0F0F0Fh ; n = (n + (n >> 4) & 0x0F0F0F0F)
imul edx,001010101h ; add by multiplying with a "magic number"
shr edx,24 ; shift result into place
ENDMThanks. That is the very thing.
Many more thanks... These links are great too.