Re: [cc65] How to prototype an assembler function?

OK, I'm about to show my lack of assembler knowledge, but I think I know
what's going on here.

; ---------------------------------------------------------------

; void __near__ __fastcall__ WriteVDC (unsigned char, unsigned char)

; ---------------------------------------------------------------


> .segment "CODE"


> .proc _WriteVDC: near


> .segment "CODE"


> ;

; {

;

 .dbg line, "WriteVDC.c", 8

 jsr     pusha


Preserve the accumulator


> ;

; r = reg;

;

 .dbg line, "WriteVDC.c", 9

 ldy     #$01


Set the Y index offset to one byte.


>  ldx     #$00


I don't know what this is for.


>  lda     (sp),y


Read into the Accumulator one byte from the stack pointer


>  sta     _r


Store the accumulator in our external variable.  Not pertinent to my library
function.


> ;

; v = val;

;

 .dbg line, "WriteVDC.c", 10

 ldy     #$00


Load Y with the index offset for the next read.


>  ldx     #$00


I still don't know why we're doing this


>  lda     (sp),y


Load the Accumulator from 0 bytes from the stack pointer


>  sta     _v


Store our result in external variable _v.


> ;

; }

;

 .dbg line, "WriteVDC.c", 11

 jsr     incsp2


Increase the stack pointer??


>  rts


Return from the function


>  .dbg line


> .endproc


OK, a couple of questions:

1) It appears that the parameters are placed in reverse order starting at
the stack pointer such that if the function is located at $C000 then the
memory would look like this:

C000 - Val parameter
C001 - Reg parameter
C002 - First byte of code

Am I reading the tea leaves correctly here?

2) Even though we preserved the original state of the Accumulator on the
stack, it does not *appear* that we have recovered it.  Is that something
that happens in the incsp2 function?

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