Masm directives for signed comparision and other problems

[rufus16]

Hello
Could someoen tell me how to change the comparision to get io worked?
I use masm.


.IF DWORD PTR[P+ECX*4] ==-1
;something

.ENDIF

P is an array with 10000 elements. I have filled  it with  -1 per byte, so it contains fffffffff. ffff  but anyway the comparision doesnt work.  COould someone tell me how to fix it?

And in native assembly, how it would look like? couldnt find anythint that would match " jump when signed and equal"

I have found one more problem, which might fix many others:



when i use something like that

DWORD PTR[P+ECX*4]

masm changes it to DWORD PTR[OFFSET P+ECX*4]
which i dont want to.

ANy idea how to fix it? ( it might fix the previous one because it was inteprpreted worng)


thanks in advanced

[qWord]

Overwrite the datatype with:

.if SDWORD ptr ... </</<=/>= ...
.endif

When testing for equality, the singe doesn't matter.

The used jump-instructions for signed compares are:
jl/jle/jg/jge dest

For more details about conditional jumps see Intel's/AMD's documentation.

[rufus16]

Then the  problem is here :

masm changes

Code Select Expand

IF DWORD PTR[P+ECX*4]

to

IF DWORD PTR[OFFSET P+ECX*4]


Do you knwo how to fix it?

[jj2007]

masm changes

Code Select Expand

IF DWORD PTR[P+ECX*4]

to

IF DWORD PTR[OFFSET P+ECX*4]


How does Masm change it??
What you probably mean is that you have a variable P like this:

Code Select Expand

.data
P dd 0
... and you want the value of [P+ecx*4]
That requires dereferencing:

Code Select Expand

mov edx, P
IF DWORD PTR[edx+ECX*4]
  ...

[rufus16]

Eh, my lack of knowledge costs alot :|

Thanks for help

[KeepingRealBusy]

Rufus16,

Just keep reading this forum and keep asking questions when you have problems. Having a short working (whether it works correctly) code example to post along with your question also helps.

Learning is allowed here.

Dave.

[dedndave]

i can tell you how i would do it....

Code Select Expand

        cmp dword ptr P[4*ecx],-1
        jnz     dont_do_it

there, now wasn't that easy ?   :bg

[Hobbit]

Interesting, more than one way to skin a cat I guess.

Ralph