mirror of
https://github.com/cc65/cc65.git
synced 2024-12-23 04:30:10 +00:00
123 lines
2.4 KiB
ArmAsm
123 lines
2.4 KiB
ArmAsm
;
|
|
; Startup code for cc65 (C64 version)
|
|
;
|
|
; This must be the *first* file on the linker command line
|
|
;
|
|
|
|
.export _exit
|
|
.import initlib, donelib
|
|
.import zerobss, push0
|
|
.import callmain
|
|
.import RESTOR, BSOUT, CLRCH
|
|
.import __RAM_START__, __RAM_SIZE__ ; Linker generated
|
|
|
|
.include "zeropage.inc"
|
|
.include "c64.inc"
|
|
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Create an empty LOWCODE segment to avoid linker warnings
|
|
|
|
.segment "LOWCODE"
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Place the startup code in a special segment.
|
|
|
|
.segment "STARTUP"
|
|
|
|
; BASIC header with a SYS call
|
|
|
|
.word Head ; Load address
|
|
Head: .word @Next
|
|
.word 1000 ; Line number
|
|
.byte $9E,"2061" ; SYS 2061
|
|
.byte $00 ; End of BASIC line
|
|
@Next: .word 0 ; BASIC end marker
|
|
|
|
; ------------------------------------------------------------------------
|
|
; 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
|
|
|
|
; Switch off the BASIC ROM
|
|
|
|
lda $01
|
|
pha ; Remember the value
|
|
and #$F8
|
|
ora #$06 ; Enable kernal+I/O, disable basic
|
|
sta $01
|
|
|
|
; Clear the BSS data
|
|
|
|
jsr zerobss
|
|
|
|
; Save system settings and setup the stack
|
|
|
|
pla
|
|
sta mmusave ; Save the memory configuration
|
|
|
|
tsx
|
|
stx spsave ; Save the system stack ptr
|
|
|
|
lda #<(__RAM_START__ + __RAM_SIZE__)
|
|
sta sp
|
|
lda #>(__RAM_START__ + __RAM_SIZE__)
|
|
sta sp+1 ; Set argument stack ptr
|
|
|
|
; Call module constructors
|
|
|
|
jsr initlib
|
|
|
|
; Push arguments and call main
|
|
|
|
jsr callmain
|
|
|
|
; Call module destructors. This is also the _exit entry.
|
|
|
|
_exit: jsr donelib ; Run module destructors
|
|
|
|
; Restore system stuff
|
|
|
|
ldx spsave
|
|
txs ; Restore stack pointer
|
|
lda mmusave
|
|
sta $01 ; Restore memory configuration
|
|
|
|
; Copy back the zero page stuff
|
|
|
|
ldx #zpspace-1
|
|
L2: lda zpsave,x
|
|
sta sp,x
|
|
dex
|
|
bpl L2
|
|
|
|
; Reset changed vectors, back to basic
|
|
|
|
jmp RESTOR
|
|
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Data
|
|
|
|
.data
|
|
|
|
zpsave: .res zpspace
|
|
|
|
.bss
|
|
|
|
spsave: .res 1
|
|
mmusave:.res 1
|