Waraxe IT Security Portal

erg0t · Valuable expert

Hi, yesterday I was iluminated and it ended in a very fast and small strlen implementation. It uses 2 general registers, two mmx registers, and has only one branch. Can be modified easly to scan for another bytes.
Here is the fasm macro:

macro strlen Param
{
mov ecx, Param
pxor mm1,mm1
sub ecx, 8
bucle:
add ecx, 8
movq mm0, [ecx]
pcmpeqb mm0,mm1
pmovmskb eax,mm0
test eax, eax
jz bucle
sub ecx, Param
bsf eax, eax
add eax, ecx
}

erg0t · Valuable expert

I optimized a little the rutine.
Benchmarks:

old

LINUX · Moderator

iluminated code Smile

personal note > pone el source del bot aka no seas careta

erg0t · Valuable expert