[stella] Common 2600 support files submission

[Manuel Rotschkar <cybergoth@xxxxxxxx>]

Hi there!

Andrew, please don't kill me for probably forcing you to 
update update the 2600 support files the third time in 
three days, but with this I'm done for this year. 
Promised. :-)

The attached ZIP files mainly contains a 4K template, 
which gives a perfect jumpstart for any 2600 
development. It does a safe, complete & working TV 
frame, yet it has very minimized overhead and is very 
small and it encapsulates all knowledge about the TV 
frame in working black-box macros.

To achieve this, I added basic PAL/NTSC support to VCS.H 
and the makros

START_VBLANK_TIMER
EXPIRE_VBLANK_TIMER
START_OVERSCAN_TIMER
EXPIRE_OVERSCAN_TIMER

to makro.h

As an appetizer, here comes the complete template source 
(All is in the ZIP again):

-------------------------------------------------------
; 4K Template
; Compiles with DASM and is tested Z26. 
; Done by Manuel Rotschkar (cybergoth@xxxxxxxx)

; Uncomment for PAL:
; COMPILE_VERSION         = PAL

    processor 6502
    include vcs.h
    include macro.h

    SEG.U   variables
    ORG     $80

frameCounter    ds 1
; Add more variable definitions here

    SEG     Bank0
    ORG     $F000

Start               
    CLEAN_START
    JSR Init

MainLoop
    VERTICAL_SYNC

    START_VBLANK_TIMER
; Add calculations during VBLANK TIME here
    EXPIRE_VBLANK_TIMER

    JSR MainScreen

    START_OVERSCAN_TIMER
; Add calculations during Overscan here
    EXPIRE_OVERSCAN_TIMER

    JMP MainLoop

Init
; Add Initialisation code here
    RTS

MainScreen
    STA WSYNC
    STA VBLANK          ; Stop vertical blank

; Replace with your own kernel code from here...

    LDX #190
DoScreen
    STA WSYNC
    STX COLUBK
    DEX
    BNE DoScreen

; to here...

    STA WSYNC
    LDA $02
    STA VBLANK          ; Start vertical blank
    RTS

; Reset Vector
    ORG        $FFFA
    .word Start
    .word Start
    .word Start
-------------------------------------------------------

Note: I did not change the version tags of vcs.h & 
macro.h, so please just take a look at all the stuff, 
but only use it after Andrew has approved and officially 
uploaded it. (If he does... at least I hope so :-))

BTW: The latest base adress fix works as intended!

Greetings,
	Manuel

Attachment: support.zip
Description: Zip archive