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mirror of https://github.com/cc65/cc65.git synced 2024-12-23 19:29:37 +00:00
cc65/libsrc/plus4/crt0.s
cuz e3b2fcc78d Move the conio initialization routines where they belong (cgetc), make them
module constructors/destructors and remove the conio init functions that
were called from the startup code.


git-svn-id: svn://svn.cc65.org/cc65/trunk@479 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-11-23 19:21:05 +00:00

131 lines
2.4 KiB
ArmAsm

;
; Startup code for cc65 (Plus/4 version)
;
; This must be the *first* file on the linker command line
;
.export _exit
.import initlib, donelib
.import push0, _main, zerobss
.include "plus4.inc"
.include "../cbm/cbm.inc"
; ------------------------------------------------------------------------
; Define and export the ZP variables for the C64 runtime
.exportzp sp, sreg, regsave
.exportzp ptr1, ptr2, ptr3, ptr4
.exportzp tmp1, tmp2, tmp3, tmp4
.exportzp regbank, zpspace
.zeropage
zpstart = *
sp: .res 2 ; Stack pointer
sreg: .res 2 ; Secondary register/high 16 bit for longs
regsave: .res 2 ; slot to save/restore (E)AX into
ptr1: .res 2
ptr2: .res 2
ptr3: .res 2
ptr4: .res 2
tmp1: .res 1
tmp2: .res 1
tmp3: .res 1
tmp4: .res 1
regbank: .res 6 ; 6 byte register bank
zpspace = * - zpstart ; Zero page space allocated
.code
; ------------------------------------------------------------------------
; BASIC header with a SYS call
.org $0FFF
.word Head ; Load address
Head: .word @Next
.word 1000 ; Line number
.byte $9E,"4109" ; SYS 4109
.byte $00 ; End of BASIC line
@Next: .word 0 ; BASIC end marker
.reloc
; ------------------------------------------------------------------------
; Actual code
ldx #zpspace-1
L1: lda sp,x
sta zpsave,x ; save the zero page locations we need
dex
bpl L1
; Close open files
jsr CLRCH
; Switch to second charset
lda #14
jsr BSOUT
; Clear the BSS data
jsr zerobss
; Save system stuff and setup 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 module constructors
jsr initlib
; Pass an empty command line
jsr push0 ; argc
jsr push0 ; argv
ldy #4 ; Argument size
jsr _main ; call the users code
; Call module destructors. This is also the _exit entry.
_exit: jsr donelib ; Run module destructors
; Restore system stuff
ldx spsave
txs
; Copy back the zero page stuff
ldx #zpspace-1
L2: lda zpsave,x
sta sp,x
dex
bpl L2
; Reset changed vectors
jmp RESTOR
.data
zpsave: .res zpspace
.bss
spsave: .res 1