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cc65/libsrc/atari/crt0.s
Christian Groessler 73df73194a fix indentation
2014-03-07 23:15:57 +01:00

202 lines
4.3 KiB
ArmAsm

;
; Startup code for cc65 (ATARI version)
;
; Contributing authors:
; Mark Keates
; Freddy Offenga
; Christian Groessler
; Stefan Haubenthal
;
.export __STARTUP__ : absolute = 1 ; Mark as startup
.export _exit, start
.import initlib, donelib
.import callmain, zerobss
.import __RESERVED_MEMORY__
.import __RAM_START__, __RAM_SIZE__
.ifdef __ATARIXL__
.import __STACKSIZE__
.import sram_init
.import scrdev
.import findfreeiocb
.forceimport sramprep ; force inclusion of the "shadow RAM preparation" load chunk
.include "save_area.inc"
.endif
.include "zeropage.inc"
.include "atari.inc"
; ------------------------------------------------------------------------
.segment "STARTUP"
rts ; fix for SpartaDOS / OS/A+
; they first call the entry point from AUTOSTRT and
; then the load addess (this rts here).
; We point AUTOSTRT directly after the rts.
; Real entry point:
start:
.ifdef __ATARIXL__
jsr sram_init
.endif
; Clear the BSS data
jsr zerobss
; Setup the stack
tsx
stx SP_save
.ifndef __ATARIXL__
; Report memory usage
lda APPMHI
sta APPMHI_save ; remember old APPMHI value
lda APPMHI+1
sta APPMHI_save+1
sec
lda MEMTOP
sbc #<__RESERVED_MEMORY__
sta APPMHI ; initialize our APPMHI value
sta sp ; setup runtime stack part 1
lda MEMTOP+1
sbc #>__RESERVED_MEMORY__
sta APPMHI+1
sta sp+1 ; setup runtime stack part 2
.else
lda #<(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
sta sp
lda #>(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
sta sp+1
.endif
; Call module constructors
jsr initlib
; Set left margin to 0
lda LMARGN
sta LMARGN_save
ldy #0
sty LMARGN
; Set keyb to upper/lowercase mode
ldx SHFLOK
stx SHFLOK_save
sty SHFLOK
; Initialize conio stuff
dey ; Set Y to $FF
sty CH ; remove keypress which might be in the input buffer
; 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 SP_save
txs ; Restore stack pointer
; Restore left margin
lda LMARGN_save
sta LMARGN
; Restore kb mode
lda SHFLOK_save
sta SHFLOK
; Restore APPMHI
lda APPMHI_save
sta APPMHI
lda APPMHI_save+1
sta APPMHI+1
.ifdef __ATARIXL__
; Atari XL target stuff...
lda PORTB_save
sta PORTB
lda RAMTOP_save
sta RAMTOP
lda MEMTOP_save
sta MEMTOP
lda MEMTOP_save+1
sta MEMTOP+1
; Issue a GRAPHICS 0 call (copied'n'pasted from TGI drivers) in
; order to restore screen memory to its defailt location just
; before the ROM.
jsr findfreeiocb
; Reopen it in Graphics 0
lda #OPEN
sta ICCOM,x
lda #OPNIN | OPNOT
sta ICAX1,x
lda #0
sta ICAX2,x
lda #<scrdev
sta ICBAL,x
lda #>scrdev
sta ICBAH,x
lda #3
sta ICBLL,x
lda #0
sta ICBLH,x
jsr CIOV_org
; No error checking here, shouldn't happen(tm), and no way to
; recover anyway.
lda #CLOSE
sta ICCOM,x
jsr CIOV_org
.endif
; Turn on cursor
ldx #0
stx CRSINH
; Back to DOS
rts
; *** end of main startup code
; ------------------------------------------------------------------------
.bss
SP_save: .res 1
SHFLOK_save: .res 1
LMARGN_save: .res 1
.ifndef __ATARIXL__
APPMHI_save: .res 2
.endif