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cc65/libsrc/atmos/crt0.s
uz 5df93d5561 Add support for interruptors (Stefan Haubenthal).
git-svn-id: svn://svn.cc65.org/cc65/trunk@5027 b7a2c559-68d2-44c3-8de9-860c34a00d81
2011-05-23 17:35:25 +00:00

154 lines
2.8 KiB
ArmAsm

;
; Startup code for cc65 (Oric version)
;
; By Debrune Jérôme <jede@oric.org> and Ullrich von Bassewitz <uz@cc65.org>
;
.export _exit
.export __STARTUP__ : absolute = 1 ; Mark as startup
.import initlib, donelib
.import callmain, zerobss, callirq
.import __INTERRUPTOR_COUNT__
.import __RAM_START__, __RAM_SIZE__
.import __ZPSAVE_LOAD__, __STACKSIZE__
.include "zeropage.inc"
.include "atmos.inc"
; ------------------------------------------------------------------------
; Oric tape header
.segment "TAPEHDR"
.byte $16, $16, $16 ; Sync bytes
.byte $24 ; End of header marker
.byte $00 ; $2B0
.byte $00 ; $2AF
.byte $80 ; $2AE Machine code flag
.byte $C7 ; $2AD Autoload flag
.dbyt __ZPSAVE_LOAD__ ; $2AB
.dbyt __RAM_START__ ; $2A9
.byte $00 ; $2A8
.byte ((.VERSION >> 8) & $0F) + '0'
.byte ((.VERSION >> 4) & $0F) + '0'
.byte (.VERSION & $0F) + '0'
.byte $00 ; Zero terminated compiler version
; ------------------------------------------------------------------------
; Place the startup code in a special segment.
.segment "STARTUP"
; Save the zero page area we're about to use
ldx #zpspace-1
L1: lda sp,x
sta zpsave,x ; Save the zero page locations we need
dex
bpl L1
; Clear the BSS data
jsr zerobss
; Unprotect columns 0 and 1
lda STATUS
sta stsave
and #%11011111
sta STATUS
; Save system stuff and setup the stack
tsx
stx spsave ; Save system stk ptr
lda #<(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
sta sp
lda #>(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
sta sp+1 ; Set argument stack ptr
; 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
; Call module constructors
NoIRQ1: jsr initlib
; Push arguments and call main()
jsr callmain
; Call module destructors. This is also the _exit entry.
_exit: jsr donelib ; Run module destructors
; Reset the IRQ vector if we chained it.
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
; Restore system stuff
NoIRQ2: ldx spsave
txs
lda stsave
sta STATUS
; Copy back the zero page stuff
ldx #zpspace-1
L2: lda zpsave,x
sta sp,x
dex
bpl L2
; Back to BASIC
rts
; ------------------------------------------------------------------------
; 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
IRQInd: jmp $0000
.segment "ZPSAVE"
zpsave: .res zpspace
.bss
spsave: .res 1
stsave: .res 1