Function calls

[britlion]

Boriel, did you notice this one?

Even with the latest stack fixed version, I'm not understanding well how to do standard function calls with parameters. Where do I find my parameters? On the stack, sure...

When I do

Code:

function thing (a as uByte, b as uByte)
asm
DI
HALT
end asm
end function

I can get the computer to stop, and have a look at the stack.

It seems to consist of:

nn
nn ; something
nn
nn ; return address
a
44h
b
44h


What is that other 16 bit value on the stack? How should I be handling parameters? StdCall isn't documented in the wiki (and I documented fastcall, through reverse engineering!)

It also means that if I pop my 8 bit value off the stack with POP BC - the 8 bit parameter ends up in B! ?

I'm worried because following the template in the asm library:

Code:

Function test(a as uByte, b as uByte) as uInteger
asm
    POP HL ; return address
    ex (sp),hl ; get operand

For this routine at least, left me in the rom, at the halt fall point, with interrupts disabled! A crash.

In order to get it to work, and put one parameter in A, and the other in DE, it looks like I have to do

Code:

POP BC ; something
    POP HL ; return address
    POP BC ; A
    LD A,B
    POP BC ; b
    LD D,0
    LD E,B
    PUSH HL ; put return address back

Four pops and a push, and some register futzing; which doesn't seem to be ideally fast!