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;
; Startup code for cc65 (C16 version)
;
; Note: The C16 is actually the Plus/4 with just 16KB of memory. So, many
; things are similar here; and, we even use the plus4.inc include file.
;
.export _exit
.export __STARTUP__ : absolute = 1 ; Mark as startup
.import initlib, donelib
.import callmain, zerobss
.import MEMTOP, RESTOR, BSOUT, CLRCH
.importzp ST
.include "zeropage.inc"
.include "plus4.inc"
; ------------------------------------------------------------------------
; Startup code
.segment "STARTUP"
Start:
; Save the zero-page locations that we need.
ldx #zpspace-1
L1: lda sp,x
sta zpsave,x
dex
bpl L1
; Switch to the second charset.
lda #14
jsr BSOUT
; Clear the BSS data.
jsr zerobss
; Save some system stuff; and, set up the stack.
tsx
stx spsave ; save system stk ptr
sec
jsr MEMTOP ; Get top memory
cpy #$80 ; We can only use the low 32K :-(
bcc MemOk
ldy #$80
ldx #$00
MemOk: stx sp
sty sp+1 ; set argument stack ptr
; Call the module constructors.
jsr initlib
; Push the command-line arguments; and, call main().
jsr callmain
; Call the module destructors. This is also the exit() entry.
_exit: pha ; Save the return code on stack
jsr donelib ; Run module destructors
; Copy back the zero-page stuff.
ldx #zpspace-1
L2: lda zpsave,x
sta sp,x
dex
bpl L2
; Store the return code into BASIC's status variable.
pla
sta ST
; Restore the stack pointer.
ldx spsave
txs
; Back to BASIC.
rts
; ------------------------------------------------------------------------
.segment "INIT"
zpsave: .res zpspace
; ------------------------------------------------------------------------
.bss
spsave: .res 1
|
