1.69.14 bug

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render

Joined: 25 Jun 2010
Posts: 14

render 16 Nov 2010, 20:28

FASM.EXE -v

Code:

flat assembler  version 1.69.14

bug in this code:

Code:

                        entry $
                     stdcall ff
proc ff
locals
variable dd ?
endl
            int 3
                       mov [variable],0x5
                  .while [variable] >= 0
                           mov ecx,ecx
                         sub [variable],0x2
                  .endw           
                    xor eax,eax
                 xor eax,eax
                 xor eax,eax
                 xor eax,eax
                 xor eax,eax
                 ret


endp

Code:

                   entry $
                     stdcall ff
proc ff
locals
variable dd ?
endl
            int 3
                       mov [variable],0x5
                  .while [variable] > 0
                            mov ecx,ecx
                         sub [variable],0x2
                  .endw           
                    xor eax,eax
                 xor eax,eax
                 xor eax,eax
                 xor eax,eax
                 xor eax,eax
                 ret


endp

16 Nov 2010, 20:28

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8359
Location: Kraków, Poland

Tomasz Grysztar 16 Nov 2010, 20:48

From documentation of Win32 programming macros on ".if"/".while" macroinstructions:

2.2 Structuring the source wrote:

The values are compared as unsigned ones.

What is not documented there is that you can actually get signed comparison if you write ".while signed [variable]>=0". It's undocumented right now, but certainly it should get covered there, so I'll add it soon.

Also note that this is related to macroinstruction package and has not much to do with fasm's executable and its version. And current version of fasm is 1.69.25, BTW.

16 Nov 2010, 20:48

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