atodw and dwtoa

[bf2]

I'd much appreciate some help with this problem I have with my little multiplication program. My plan was to multiply two numbers and then string together the contents of EAX and EDX to display it, but I haven't got that far. I got stuck at the atodw and dwtoa macros.

Code Select Expand

.386
.model flat,stdcall
option casemap:none

include \masm32\include\kernel32.inc
include \masm32\include\masm32.inc
include \masm32\include\user32.inc
include \masm32\include\windows.inc

includelib \masm32\lib\kernel32.lib
includelib \masm32\lib\masm32.lib
includelib \masm32\lib\user32.lib

.data
Caption  byte "Result",0

mult1 byte "20", 0
mult2 byte "60", 0

result byte 4 DUP(?)

.code
start:
atodw mult2
mov ebx, eax
atodw mult1
mul ebx
dwtoa eax, addr result
invoke MessageBox, NULL, addr result, addr Caption, MB_OK

invoke ExitProcess, NULL

end start

I am getting the following assembly errors:

Code Select Expand

>ml /c /coff /Cp Test.asm
Microsoft (R) Macro Assembler Version 6.14.8444
Copyright (C) Microsoft Corp 1981-1997.  All rights reserved.

Assembling: Test.asm
\masm32\include\windows.inc(98) : error A2005: symbol redefinition : CHAR
Test.asm(24) : error A2008: syntax error : atodw
Test.asm(26) : error A2008: syntax error : atodw
Test.asm(28) : error A2008: syntax error : eax

I am sure I have made some silly syntax errors somewhere in calling the macros, but don't know where.

Thanks in advance.

[Gunner]

a few things:

The symbol redef... windows.inc should be before EVERY include, should be the first include file...


atodw and dwtoa require a pointer to the ascii string, and you have to call or invoke em:

invoke atodw, offset multi2
invoke dwtoa, eax,  addr result

[jj2007]

Second problem will be the lack of the macros. Use

Code Select Expand

include \masm32\include\masm32rt.inc

.data
...

instead of the bunch of includes you have above. Have a look at \masm32\include\masm32rt.inc in an editor, it's a good lecture.

[bf2]

Thanks for the comments, they have solved the problem.

Now on to the main problem: i.e. displaying contents of EAX and EDX after a multiplication. Some weird things are happening. Apologies for the long post.

First this code:

Code Select Expand

.386
.model flat,stdcall
option casemap:none

include \masm32\include\masm32rt.inc

.data
caption  byte "Result",0

mult1 byte "500", 0
mult2 byte "600", 0

result0 dword ?
result1 dword ?
result2 dword ?

.code
start:
invoke atodw, offset mult2
mov ebx, eax
invoke atodw, offset mult1
mul ebx


; BLOCK 0
invoke dwtoa, eax, addr result0
invoke MessageBox, NULL, addr result0, addr caption, MB_OK

; BLOCK 1
;invoke dwtoa, edx, addr result1
;invoke MessageBox, NULL, addr result1, addr caption, MB_OK

; BLOCK 2
;invoke dwtoa, eax, addr result2
;invoke MessageBox, NULL, addr result2, addr caption, MB_OK

invoke ExitProcess, NULL

end start

This code above is producing a messagebox with 300000 on it, so that's all good. No problem. The numbers are small, so the product is contained in EAX and presumably EDX is set to zero.

If I now comment out BLOCK 0 and uncomment BLOCK 1 and BLOCK 2 to see what's in EDX and EAX, like this:

Code Select Expand

.386
.model flat,stdcall
option casemap:none

include \masm32\include\masm32rt.inc

.data
caption  byte "Result",0

mult1 byte "500", 0
mult2 byte "600", 0

result0 dword ?
result1 dword ?
result2 dword ?

.code
start:
invoke atodw, offset mult2
mov ebx, eax
invoke atodw, offset mult1
mul ebx


; BLOCK 0
;invoke dwtoa, eax, addr result0
;invoke MessageBox, NULL, addr result0, addr caption, MB_OK

; BLOCK 1
invoke dwtoa, edx, addr result1
invoke MessageBox, NULL, addr result1, addr caption, MB_OK

; BLOCK 2
invoke dwtoa, eax, addr result2
invoke MessageBox, NULL, addr result2, addr caption, MB_OK

invoke ExitProcess, NULL

end start

Then the code above is producing two mesage boxes, the first one with 0 on it, and the second one with 1.

How is this possible? How can EAX suddenly contain 1?

Even worse, if I now uncomment all the blocks:

Code Select Expand

.386
.model flat,stdcall
option casemap:none

include \masm32\include\masm32rt.inc

.data
caption  byte "Result",0

mult1 byte "500", 0
mult2 byte "600", 0

result0 dword ?
result1 dword ?
result2 dword ?

.code
start:
invoke atodw, offset mult2
mov ebx, eax
invoke atodw, offset mult1
mul ebx


; BLOCK 0
invoke dwtoa, eax, addr result0
invoke MessageBox, NULL, addr result0, addr caption, MB_OK

; BLOCK 1
invoke dwtoa, edx, addr result1
invoke MessageBox, NULL, addr result1, addr caption, MB_OK

; BLOCK 2
invoke dwtoa, eax, addr result2
invoke MessageBox, NULL, addr result2, addr caption, MB_OK

invoke ExitProcess, NULL

end start 
then I am getting three message boxes, showing 300000, then 1312264 and 1, respectively. So now according to my program, EDX contains 1312264 !!!

I am bewildered.

[jj2007]

I am bewildered.

Take it easy, and read the stuff on register preservation :bg

[Gunner]

eax gets overwritten by the return value of message box... If you want an handy way of printing strings and numbers... you can use the vkim debug macros... you can do PrintDec eax

Add this to your includes
include \masm32\vkdebug\dbproc\debug.inc
includelib \masm32\vkdebug\dbproc\debug.lib

look in those directories for more info  :toothy

[jj2007]

If you want an handy way of printing strings and numbers... you can use the vkim debug macros... you can do PrintDec eax

PrintDec opens an extra window, which I find a bit annoying. For 'inline' debugging, consider the MasmBasic deb macro:

include \masm32\MasmBasic\MasmBasic.inc   ; download
uselib debug

.data
MyReal4   REAL4 1234.5678
MyReal10   REAL10 12345678.9012345678
MyQword   QWORD 123456789012345678

   Init
   MovVal xmm0, "123456789012345678"   ; load an integer into xmm0
   MovVal f:xmm1, "123456789.01234567890"   ; load a float into xmm1
   mov ecx, Val("60")           ; Val is the atodw equivalent of MasmBasic
   mov eax, Val("80")
   imul eax, ecx
   mov edx, 123
   PrintDec eax
   PrintDec ecx
   PrintDec edx
   PrintDec MyReal4   ; incorrect result
   PrintDec MyQword   ; incorrect result
   ; PrintDec xmm0 won't work
   fldpi   ; push PI on the FPU
   deb 4, "Results", eax, ecx, edx, xmm0, f:xmm1, ST(0), MyReal4, MyReal10, MyQword
   Inkey "Hit any key"
   Exit
end start

PrintDec output:
eax = 4800 (tmp_file.asm, 16)
ecx = 60 (tmp_file.asm, 17)
edx = 123 (tmp_file.asm, 18)
MyReal4 = 1150964267 (tmp_file.asm, 19)
MyQword = 0 (tmp_file.asm, 20)

deb output:
Results
eax             4800
ecx             60
edx             123
xmm0            1.234567890123457e+17
f:xmm1          123456789.0123457
ST(0)           3.14159265358979324
MyReal4         1234.568
MyReal10        12345678.9012345678
MyQword         123456789012345678

[bf2]

Thank you, thank you all. I thought I was going mad.