mirror of
https://github.com/cc65/cc65.git
synced 2024-11-17 09:07:32 +00:00
151 lines
3.0 KiB
ArmAsm
151 lines
3.0 KiB
ArmAsm
;
|
|
; Startup code for cc65 (Vic20 version)
|
|
;
|
|
; This must be the *first* file on the linker command line
|
|
;
|
|
|
|
.export _exit
|
|
.import initlib, donelib, callirq
|
|
.import zerobss, push0
|
|
.import callmain
|
|
.import RESTOR, BSOUT, CLRCH
|
|
.import __INTERRUPTOR_COUNT__
|
|
.import __RAM_START__, __RAM_SIZE__ ; Linker generated
|
|
|
|
.include "zeropage.inc"
|
|
.include "vic20.inc"
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Place the startup code in a special segment.
|
|
|
|
.segment "STARTUP"
|
|
|
|
; BASIC header with a SYS call
|
|
|
|
.word Head ; Load address
|
|
Head: .word @Next
|
|
.word .version ; Line number
|
|
.byte $9E ; SYS token
|
|
.byte <(((@Start / 1000) .mod 10) + $30)
|
|
.byte <(((@Start / 100) .mod 10) + $30)
|
|
.byte <(((@Start / 10) .mod 10) + $30)
|
|
.byte <(((@Start / 1) .mod 10) + $30)
|
|
.byte $00 ; End of BASIC line
|
|
@Next: .word 0 ; BASIC end marker
|
|
@Start:
|
|
|
|
; ------------------------------------------------------------------------
|
|
; 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 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
|
|
|
|
; If we have IRQ functions, chain our stub into the IRQ vector
|
|
|
|
lda #<__INTERRUPTOR_COUNT__
|
|
beq NoIRQ1
|
|
lda IRQVec
|
|
ldx IRQVec+1
|
|
sta IRQInd+1
|
|
stx IRQInd+2
|
|
lda #<IRQStub
|
|
ldx #>IRQStub
|
|
sei
|
|
sta IRQVec
|
|
stx IRQVec+1
|
|
cli
|
|
|
|
; Push arguments and call main()
|
|
|
|
NoIRQ1: jsr callmain
|
|
|
|
; Back from main (This is also the _exit entry). Reset the IRQ vector if we
|
|
; chained it.
|
|
|
|
_exit: pha ; Save the return code on stack
|
|
lda #<__INTERRUPTOR_COUNT__
|
|
beq NoIRQ2
|
|
lda IRQInd+1
|
|
ldx IRQInd+2
|
|
sei
|
|
sta IRQVec
|
|
stx IRQVec+1
|
|
cli
|
|
|
|
; Run module destructors
|
|
|
|
NoIRQ2: jsr donelib
|
|
|
|
; Copy back the zero page stuff
|
|
|
|
ldx #zpspace-1
|
|
L2: lda zpsave,x
|
|
sta sp,x
|
|
dex
|
|
bpl L2
|
|
|
|
; Place the program return code into ST
|
|
|
|
pla
|
|
sta ST
|
|
|
|
; Restore the stack pointer
|
|
|
|
ldx spsave
|
|
txs
|
|
|
|
; Reset changed vectors, back to basic
|
|
|
|
jmp RESTOR
|
|
|
|
|
|
; ------------------------------------------------------------------------
|
|
; The IRQ vector jumps here, if condes routines are defined with type 2.
|
|
|
|
IRQStub:
|
|
cld ; Just to be sure
|
|
jsr callirq ; Call the functions
|
|
jmp IRQInd ; Jump to the saved IRQ vector
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Data
|
|
|
|
.data
|
|
|
|
zpsave: .res zpspace
|
|
IRQInd: jmp $0000
|
|
|
|
.bss
|
|
|
|
spsave: .res 1
|