code clarification

[shankle]

Can't find a good explanation for this code in the Microsoft Macro Assembler Programmer's guide.
fld1  db '01234',0
esi  value is 2

mov ah, byte ptr fld1[esi]
mov ah, byte ptr[fld1+esi]

I think they are the same - maybe wrong
My program is having fits because of this.

[qWord]

FLD1 is an FPU-intruction - you can't use 'fld1' as label.

[shankle]

It is just an example.
Call it bldf1

[hutch--]

Jack,

What are you trying to do ?

The data,

Code Select Expand


  nums db "1234",0


is a byte sequence or string if you like.

What are you after, 1 byte in each register ?

[jj2007]

My program is having fits because of this.

Your program is "having fits" because, as qWord rightly noted, you are using bad labels.

Code Select Expand

include \masm32\include\masm32rt.inc

.code
fldX  db '01234',0
start:
mov esi, 2
movzx eax, byte ptr fldX[esi]

MsgBox 0, str$(eax), "Test:", MB_OK
exit

end start


[shankle]

Thanks fellows for responding.
I wrote a little program to test the 2 versions as I should have done before belaboring
you all with my problems.
If you compile the program you will see that the two versions of the "mov"
give the same results.
So it is something else causing trouble in the program that I am writing which
I will have to solve.
See attached.

[mineiro]

This are happening because you "xor esi" Sr shankle.
bldf1            db   '54321',0

     xor esi, esi
     mov ah, byte ptr bldf1[esi]        ;get byte at location zero of bldf1 (index 0)
     mov ah, byte ptr[bldf1+esi]       ;get byte at location esi of bldf1   (index 0)

     inc esi                                    ;index 1
     mov ah,byte ptr [bldf1+esi]      ;bldf1 + index 1

you can put displacement direct in expression too, like:
     mov ah, bldf1             ;ah = 5
     mov ah, [bldf1+1]       ;ah = 4
     mov ah, [bldf1+esi+2]  ;ah = 3
     inc esi
     mov ah, [bldf1+esi+2]  ;ah = 2

[shankle]

Thank you for responding Sr Mineiro.
That was just a sample to show that the 1st byte gave the same results
with both versions of the "mov" statement.
I f I put that code in a ".while" loop I would have to increment
esi to get to the rest of bldf1.