Assembler Functions, Params and Variables

[Charles Pegge]

Code: [Select]

include "$/inc/console.inc"
indexbase 0

! funA cdecl (sys a,b,c,d) as sys at _funA
jmp fwd nfun
._funA
push ebp
mov  ebp,esp
sub  esp,0x100
scope
  sys  a at [ebp+0x08]
  sys  b at [ebp+0x0C]
  sys  c at [ebp+0x10]
  sys  d at [ebp+0x14]
  sys  r at edx
  sys  i at ecx
  r=0
  for i=1 to 10
     r=r+a+b+c+d
  next
  =r
end scope
mov  esp,ebp
pop ebp
ret
.nfun

'print "here"
sys a
a=funA 1,2,3,4
print a
waitkey


[JRS]

You know how to hurt a guy. 

I'm still looking for the magic hooker that knows the ins and outs of BASIC functions.

[Mike Lobanovsky]

Hi Charles,

What does =r mean?

[JRS]

OT - Where you been? On vacation?

[Charles Pegge]

Hi Mike,

=r
-->
mov eax,r
-->
mov eax,edx



Also works with floats

float s
#show =s
-->
fld dword [ebx+0x1000]

[Charles Pegge]

Another trick for improving performance in simple numeric procedures, is to use the bespoke cpu calling convention:

Instead of passing params on the stack, registers  ecx,edx,esi,edi, are used. (max 4 params.)

Code: [Select]

include "$/inc/console.inc"
indexbase 0

function funA cpu (a,b,c,d) as sys
#show return a+(b*c)+d
end function

sys a
#show a=funA 1,2,3,4
print a
waitkey


[Emil_halim]

nice work Charles,

but why you don't use registers as a parameters

e.g.

Code: [Select]

include "$/inc/console.inc"
indexbase 0

function funA cpu (ecx,edx,esi,edi) as sys
#show return ecx+(edx*esi)+edi
end function

sys a
#show a=funA 1,2,3,4
print a
waitkey


[Charles Pegge]

Hi Emil,

The registers are platform-specific.

In 64 bit mode the registers will be  rcx  rdx  r8  r9

[Emil_halim]

The registers are platform-specific.

In 64 bit mode the registers will be  rcx  rdx  r8  r9

i think it is not aproblem at all , with 32bits use ecx,....  and with 64bits use rec,.....

thanks ,

just want to know how much is Oxygen basic bug free?

[Charles Pegge]

Hi Emil,

There are plenty more bugs. I guarantee it

Most of them are to be found in C/Basic mixed syntax, and the more complex constructs. But within simple Basic and Assembler, you are fairly safe.