How to access a 'Static' variable with inline assembly?

Mijikai · **Joined:** Sun Sep 11, 2016 2:17 pm **Posts:** 803

How can i change the content of 'Address' with inline assembly?

Code:

Code:

;PB x64 v.5.62

Procedure.i TestFnc()
  Static Address.i
  !mov qword[p.v_Address],123;<- does not work for 'Static' !
  Debug Address
EndProcedure

TestFnc()

Fred · **Posted:** Fri May 11, 2018 8:46 am

If you want to look that, the best is to generate the assembly code with the commandline compiler (--commented switch) and look how it is named. You will save a lot of time when using inline ASM.

Mijikai · **Joined:** Sun Sep 11, 2016 2:17 pm **Posts:** 803

Fred wrote:

If you want to look that, the best is to generate the assembly code with the commandline compiler (--commented switch) and look how it is named. You will save a lot of time when using inline ASM.

Thanks

Heres how it works:

Code:

;-> so_PROCEDURENAME.v_VARIABLE

I found something im curious about:

If we have a Procedure that does not return a value PB does this:

Code:

...
xor rax,rax
add rsp,28
ret

However if we return a value it looks like this:

Code:

...
jmp @f
xor rax,rax
@@:
add rsp,28
ret 

why is the jmp & xor even in there ?

wilbert · **Posted:** Fri May 11, 2018 9:28 am

Mijikai wrote:

How can i change the content of 'Address' with inline assembly?

You could do it like this

Code:

;PB x64 v.5.62

Procedure.i TestFnc()
  Static Address.i
  Protected *Address = @Address
  !mov rdx, [p.p_Address]
  !mov qword [rdx],123
  Debug Address
EndProcedure

TestFnc()

It does produce a bit of additional code and therefore is slightly slower but it does have the advantage that the reference to *Address (local variable) stays the same.
The reference to a static value changes when the procedure is included in a module.

Mijikai · **Joined:** Sun Sep 11, 2016 2:17 pm **Posts:** 803

wilbert wrote:

...

Code:

;PB x64 v.5.62
Procedure.i TestFnc()
  Static Address.i
  Protected *Address = @Address
  !mov rdx, [p.p_Address]
  !mov qword [rdx],123
  Debug Address
EndProcedure

TestFnc()

It does produce a bit of additional code and therefore is slightly slower but it does have the advantage that the reference to *Address (local variable) stays the same.
The reference to a static value changes when the procedure is included in a module.

Thanks, i didnt think of that way

CELTIC88 · **Joined:** Thu Sep 17, 2015 3:39 pm **Posts:** 147

Mijikai wrote:

...
I found something im curious about:

If we have a Procedure that does not return a value PB does this:

Code:

...
xor rax,rax
add rsp,28
ret

However if we return a value it looks like this:

Code:

...
jmp @f
xor rax,rax
@@:
add rsp,28
ret 

why is the jmp & xor even in there ?

so that "PB" can be adapted to any scenario
"is complex process!"
but you can optimize that.

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