64 bit strange macro behavior ?

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Roman

Joined: 21 Apr 2012
Posts: 1373

Roman 12 Dec 2020, 09:13

I write this macro

Code:

macro vCall  cT,[arg] {
              forward
              mov rcx,arg
              mov rdx,arg
              mov r8,arg
              mov r9,arg
              common
              Call cT
                               }

If i write in code vCall procA,0,2
I get this:

Code:

mov rcx,0
mov rdx,0
mov r8,0
mov r9,0
mov rcx,2
mov rdx,2
mov r8,2
mov r9,2
Call procA

But i want get like do invoke(but invoke big macro).

Code:

mov rcx,0
mov rdx,2
Call procA

Or vCall procA,1

Code:

mov rcx,1
Call procA

Or vCall procA

Code:

Call procA

12 Dec 2020, 09:13

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 19257
Location: In your JS exploiting you and your system

revolution 12 Dec 2020, 09:36

At the very least you need something to count which arg you have in the forward loop:

Code:

macro vCall  cT,[arg] {
    common
        arg_index = 0
    forward
        if arg_index = 0
                mov rcx,arg
        else if arg_index = 1
                mov rdx,arg
        else if arg_index = 2
                mov r8,arg
        else if arg_index = 3
                mov r9,arg
        else
                err "too many args"
        end if
        arg_index = arg_index + 1
    common
        Call cT
}

12 Dec 2020, 09:36

ProMiNick

Joined: 24 Mar 2012
Posts: 728
Location: Russian Federation, Sochi

ProMiNick 12 Dec 2020, 09:53

Code:

macro vCall  cT,torcx:rcx,tordx:rdx,tor8:r8,tor9:r9,[arg] {
              forward
              ; thour original macro does nothing with 5th and later args, so I left only comment here
              common
              if ~torcx eq rcx
                mov rcx,torcx
              end if
              if ~tordx eq rdx
                mov rdx,tordx
              end if
              if ~tor8 eq r8
                mov r8,tor8
              end if
              if ~tor9 eq r9
                mov r9,tor9
              end if
              Call cT}

I like to separate stack args from register args because they have different nature.

or even so

Code:

macro invok4  cT,torcx:rcx,tordx:rdx,tor8:r8,tor9:r9 {
              if torcx eq rcx
                mov rcx,torcx
              end if
              if tordx eq rdx
                mov rdx,tordx
              end if
              if tor8 eq r8
                mov r8,tor8
              end if
              if tor9 eq r9
                mov r9,tor9
              end if
              Call [cT]}

that is then x64 invoke, and less less less (less ...) gready for preprocessor resources(memory & compilation time) in cases of apicalls with 4 and less args.
64bit call is greadyest macro ever written in fasm standart package.

12 Dec 2020, 09:53

Roman

Joined: 21 Apr 2012
Posts: 1373

Roman 12 Dec 2020, 10:47

Thanks !

12 Dec 2020, 10:47

DimonSoft

Joined: 03 Mar 2010
Posts: 1197
Location: Belarus

DimonSoft 12 Dec 2020, 21:09

I can’t find any notion of the colon-syntax (pun not intended) in the documentation, but it works. Have I missed something about the preprocessor and its treatment of the character?

ProMiNick wrote:

Code:

macro vCall  cT,torcx:rcx,tordx:rdx,tor8:r8,tor9:r9,[arg]

12 Dec 2020, 21:09

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 19257
Location: In your JS exploiting you and your system

revolution 12 Dec 2020, 22:38

It is a default value if nothing it supplied.

12 Dec 2020, 22:38

DimonSoft

Joined: 03 Mar 2010
Posts: 1197
Location: Belarus

DimonSoft 13 Dec 2020, 12:42

revolution wrote:

It is a default value if nothing it supplied.

I assumed it could be that but FASM.pdf says it’s = character that is used for default values. I feel I’ve seen a discussion of the feature at the forum some time ago but can’t recall any details.

13 Dec 2020, 12:42

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 19257
Location: In your JS exploiting you and your system

revolution 13 Dec 2020, 12:47

Both work fine:

Code:

macro x val=0 { display val+'0' }
macro y val:0 { display val+'0' }
x
x 1
y
y 1

;output:
;0101
;1 passes, 0 bytes.

13 Dec 2020, 12:47

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