"error A2022" bug? (with EAX)

[Broken Sword]

Hi guys. What's wrong with mov reg, [EAX...] constructions ?
"error A2022: instruction operands must be the same size" is displayed in all cases we use "EAX" in the right part.

[ramguru]

You're pointing to memory and therefore must specify what you want from it byte word dword
mov eax, dword ptr [eax]
mov ax, word ptr [eax]
mov al, byte ptr [eax]

[mnemonic]

Hello,

how about a real life example?

Hi guys. What's wrong with mov reg, [EAX...] constructions ?
"error A2022: instruction operands must be the same size" is displayed in all cases we use "EAX" in the right part.

If you code:

Code Select Expand

mov dx, eax;
The error is legitimate because you are trying to mov 32bit into a 16bit destination.
You must use a 32bit register as destination register in that case.

Also refer to the above post if you are dealing with pointers.
Take care on the size. Assembler is not happy about "implict things"  :wink

[Broken Sword]

:) thanks guys, but i'm not so lame in MASM...

look:

mov eax, [ebx+0Ch] ; no error
mov ecx, [edx*2+4] ; no error
mov ebx, [eax+4] ; error A2022!!!

understand? ;)

[mnemonic]

look:

mov eax, [ebx+0Ch] ; no error
mov ecx, [edx*2+4] ; no error
mov ebx, [eax+4] ; error A2022!!!

understand? ;)

Thats why I asked for an example. Figuring something out isn´t really good...

BUT:

Code Select Expand


.386
.model flat, stdcall
option casemap:none
include \masm32\include\windows.inc
include \masm32\include\kernel32.inc
includelib kernel32.lib
include \masm32\include\user32.inc
includelib user32.lib

.data
MsgCaption      db "Iczelion's tutorial no.2",0
MsgBoxText      db "Win32 Assembly is Great!",0

.code
start:
      push ebx
      push eax
      mov eax, offset MsgCaption
      mov ebx, [eax+4]
      pop eax
      pop ebx
invoke MessageBox, NULL,addr MsgBoxText, addr MsgCaption, MB_OK
invoke ExitProcess,NULL
end start


The above example assembles, links and executes just fine...

:) thanks guys, but i'm not so lame in MASM...

Really?

Regards

[Broken Sword]

Holly Christ... It was my mistake... I've forgot 'bout

assume reg:nothing

before using

mov ..., [reg...] constructions.

nice nolame bug :)

Reggards.