Customizing FASM

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Tommy

Joined: 17 Jun 2003
Posts: 489
Location: Norway

Tommy 01 Jul 2003, 08:13

Hi Privalov!

Thanks once again for your excellent work!

A little question...:
How am I going to add an instruction or a directive which declares a symbol/label?? For instance if I'm going to make a directive with name "makelabel" which does as following:

Code:

makelabel a_name
 |
 V
a_name:
push eax

How am I going to write these sources in the FASM core??

Do you understand what I mean?? (Sorry my English)

Well, so long! Take care!
Regards,
Tommy

01 Jul 2003, 08:13

scientica
Retired moderator

Joined: 16 Jun 2003
Posts: 689
Location: Linköping, Sweden

scientica 01 Jul 2003, 12:56

Why do you want an instruction/directive to make a label?

in fasm.txt privalov wrote:

The last and the most flexible way to define labels is to use "label"
directive. This directive should be followed by the name of label, then
optionally size operator (it can be preceded by a colon) and then - also
optionally "at" operator and the numerical expression defining the address at
which this label should be defined. For example "label wchar word at char"
will define a new label for the 16-bit data at the address of "char". Now the
instruction "mov ax,[wchar]" will be after compilation the same as
"mov ax,word [char]". If no address is specified, "label" directive defines
the label at current offset. Thus "mov [wchar],57568" will copy two bytes
while "mov [char],224" will copy one byte to the same address.

_________________
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01 Jul 2003, 12:56

Tommy

Joined: 17 Jun 2003
Posts: 489
Location: Norway

Tommy 01 Jul 2003, 13:40

That was only an example... I want an instruction in which declares a label and output some bytes to the output file... (Please don't suggest macros) I only want to know how to do it, you'll probably see what it will be used for later.... Wink

So, do you know how?

Thanks for your reply anyway.... So long!
Tommy

01 Jul 2003, 13:40

scientica
Retired moderator

Joined: 16 Jun 2003
Posts: 689
Location: Linköping, Sweden

scientica 02 Jul 2003, 11:19

Tommy wrote:

That was only an example... I want an instruction in which declares a label and output some bytes to the output file...

Ok, sorry I miss understood you. Embarassed

02 Jul 2003, 11:19

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8351
Location: Kraków, Poland

Tomasz Grysztar 02 Jul 2003, 12:00

You'll probably have a good reference when I finish the internals documentation, but currently I can only provide you with a small example. You'll have to make three modifications, I give line numbers for the 1.47 version of core. First you have to put two new lines into the X86.INC file, between the lines 7730 and 7731 (after the definition of cvttss2si instruction handler):

Code:

 db 'makelabel',0
 dw makelabel_directive-assembler

The you have to put two new lines into the PARSER.INC file, in line, after the line 178 add:

Code:

        cmp     bx,makelabel_directive-assembler
        je      parse_label_directive

And finally you have to put the handler for newly defined directive into ASSEMBLE.INC file, you can put it anywhere:

Code:

makelabel_directive:
        lods    byte [esi]
        cmp     al,2
        jne     invalid_argument
        lods    dword [esi]
        cmp     eax,0Fh
        jb      invalid_use_of_symbol
        je      reserved_word_used_as_symbol
        inc     esi
        mov     ebx,eax
        xor     cl,cl
        mov     eax,edi
        sub     eax,[org_origin]
        cdq
        mov     ebp,[org_sib]
        call    operand_32bit_prefix
        mov     byte [edi],50h
        inc     edi
        jmp     define_free_label

Directive defined this way should work exactly as in your example above.

02 Jul 2003, 12:00

Tommy

Joined: 17 Jun 2003
Posts: 489
Location: Norway

Tommy 03 Jul 2003, 09:08

I understand scientica.... Smile

Thank you Privalov! Exactly what I needed.... Thanks again!

So long!
Tommy

03 Jul 2003, 09:08

Tommy

Joined: 17 Jun 2003
Posts: 489
Location: Norway

Tommy 04 Jul 2003, 08:49

When we're talking about custom instructions etc., what about adding your old tutorial on how to customize FASM instructions etc. to the documentation??

Regards,
Tommy

04 Jul 2003, 08:49

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