Macro behaves differently in test vs real code

[jj2007]

This is inspired by MichaelW, see this post.
First, the simple part:

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CrtString MACRO var, BufLen
LOCAL lbl
.data?
align 4
lbl label byte
ORG $+BufLen-1
db ?
.data
var dd lbl ;; define it in the data section
.code
ENDM


This is a great little helper - just call it as CrtString File$, MAX_PATH (without declaring File$ earlier!).
Now I wanted to be clever and got banged over the head: I included the possibility to use a register as the first argument:

CreateBuffer edi, BufSize

It works perfectly, so it seems:

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+Path$+
ir1=0
ir2=0
ACTION: Path$ dd ??0019

+EBX+
ir1=0
ir2=21
ACTION: mov EBX, offset ??001E

+edi+
ir1=17
ir1=17
ACTION: mov edi, offset ??0022


But disable .err and run it through Olly to discover that ML.EXE does something different from what the echos suggest...

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include \masm32\include\masm32rt.inc

CreateBuffer MACRO var, BufLen
LOCAL lbl, IsReg, tmp$, x$
echo
tmp$ CATSTR <+>,<var>,<+>
% echo tmp$
% IsReg INSTR <+eax+ecx+edx+esi+edi+ebx+>, <tmp$>
x$ CATSTR <ir1=>, %IsReg
% echo x$
if IsReg eq 0
% IsReg INSTR <+EAX+ECX+EDX+ESI+EDI+EBX+>, <tmp$>
x$ CATSTR <ir2=>, %IsReg
endif
% echo x$
.data?
align 4
lbl label byte
ORG $+BufLen-1
db ?
% if IsReg
echo ACTION: mov var, offset lbl
mov var, offset lbl ;; pass a pointer to the register
else
.data
echo ACTION: var dd lbl
var dd lbl ;; define it in the data section
endif
.code
ENDM

.data?
dx1 dd ?

.code
; «««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««
start:
; «««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««
BufSize equ 10000000 ; 100 MB: 200 ms extra, 1 GB: 50 seconds
; int 3 ; breakpoint for Olly
mov dx1, 11111111h ; for debugging - see where the pointer to Path$ is being put
nop
CreateBuffer Path$, BufSize
nop
CreateBuffer EBX, BufSize
nop
CreateBuffer edi, BufSize
nop
echo
; .err        ; <--- comment out to run the code
mov ebx, edi
sub ebx, Path$
MsgBox 0, str$(ebx), "CreateBuffer test:", MB_OK

xor ebx, ebx
.While ebx < BufSize
mov BYTE PTR[edi+ebx], 255
movzx eax, BYTE PTR[edi+ebx]
.IF eax != 255
print "oops",13,10
.ENDIF
inc ebx
.Endw
inkey "Press any key to exit..."
exit
; «««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««««
end start


[qWord]

hi,

because I'm hating local macro variables, I've just rewritten your macro. it seems like it works propper :bg

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CreateBuffer macro var,BufLen

IFNDEF CrBu_lbl_cntr
CrBu_lbl_cntr = 0
ELSE
CrBu_lbl_cntr = CrBu_lbl_cntr + 1
ENDIF

CrBu_str TEXTEQU <CrBu_buffer_>,%CrBu_lbl_cntr
CrBu_num = 0

FOR reg,<eax,ecx,edx,esi,edi,ebx>
IFIDNI <reg>,<var>
CrBu_num = 1
EXITM
ENDIF
ENDM

.data?
align 4
;CrBu_str db BufLen dup(?)
CrBu_str label byte
ORG $+BufLen-1
db ?
.code

IF CrBu_num NE 0
mov var,OFFSET CrBu_str
ELSE
.data
align 4
var dd OFFSET CrBu_str
.code
ENDIF

endm


EDIT:

I've just found your failure: you've forgot do change to code-segment before "mov var,.."

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CreateBuffer MACRO var, BufLen
LOCAL lbl, IsReg, tmp$, x$
echo
tmp$ CATSTR <+>,<var>,<+>
% echo tmp$
% IsReg INSTR <+eax+ecx+edx+esi+edi+ebx+>, <tmp$>
x$ CATSTR <ir1=>, %IsReg
% echo x$
if IsReg eq 0
% IsReg INSTR <+EAX+ECX+EDX+ESI+EDI+EBX+>, <tmp$>
x$ CATSTR <ir2=>, %IsReg
endif
% echo x$
.data?
align 4
lbl label byte
ORG $+BufLen-1
db ?
% if IsReg
echo ACTION: mov var, offset lbl
.code
mov var, offset lbl ;; pass a pointer to the register

else
.data
echo ACTION: var dd lbl
var dd lbl ;; define it in the data section
.code
endif

ENDM






regards
qWord

[jj2007]

I've just found your failure: you've forgot do change to code-segment before "mov var,.."[/b]

regards
qWord

You are genius, thanks a lot :U
What's wrong with local mac vars, by the way?

[qWord]

What's wrong with local mac vars, by the way?

->  1.  there are only  ~65536~ local variables available - I've just reached this limed some years ago while writing a huge macro-system  :'(
     2.  i can't remember exactly why i "hate" them, but it goes back to time when I started writing macros. Eventually it was triggered by frustration or some thing like that  :bg

[jj2007]

->  1.  there are only  ~65536~ local variables available - I've just reached this limed some years ago while writing a huge macro-system  :'(

Wow, sounds impressing! I'll keep that in mind.

For those who write smaller proggies, here the final version:

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crtbuf MACRO var, BufLen
LOCAL lbl, IsReg

IsReg INSTR <+eax+ecx+edx+esi+edi+ebx+>, @CatStr(<+>,<var>,<+>)
if IsReg eq 0
IsReg INSTR <+EAX+ECX+EDX+ESI+EDI+EBX+>, @CatStr(<+>,<var>,<+>)
endif

.data?
align 4
  lbl LABEL byte
  ORG $+BufLen-1
  db ?
if IsReg
  .code
mov var, offset lbl ;; pass a pointer to the register
else
  .data
var dd lbl ;; define it in the data section
  .code
endif
ENDM

Usage (remember these variables must not have been declared before!):

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.code
start:
crtbuf Path$, MAX_PATH
crtbuf IniFile$, MAX_PATH
crtbuf FatBuffer, 1000000
crtbuf edi, 1000
crtbuf EDI, 1000000


The crtbuf Path$, MAX_PATH is somewhat shorter than MichaelW's original macro, because it uses the equivalent of

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.data?
MyBuffer  db MAX_PATH dup (?)
.data
Path$  dd Mybuffer

instead of a mov Path$, offset MyBuffer

I have tested it with 6*100 MB under Windows XP, no problem, except when loading it into OllyDbg you get a message that Olly cannot allocate so much memory.

[herge]

 Hi jj2007:

You only need inkey
instead of

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inkey "Press any key to exit..."


Press any key to exit...
is the dafault for inkey macro.

Regards herge.

[MichaelW]

The default is "Press any key to continue ..."

[jj2007]

The default is "Press any key to continue ..."

Please change to

inkey "Hit any key to get outta here quickly"  :wink

Since we are back into philosophical debates: Any suggestions for a better name?
crtbuf Path$, MAX_PATH
createbuffer Path$, MAX_PATH
mkbuf Path$, MAX_PATH
mkstr Path$, MAX_PATH
...?

[hutch--]

 :bg

hmmmph,

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    outa_here:


Is my standard exit label. :P