mirror of
https://github.com/cc65/cc65.git
synced 2024-11-19 21:32:19 +00:00
140 lines
3.2 KiB
ArmAsm
140 lines
3.2 KiB
ArmAsm
;
|
|
; Startup code for cc65 (C64 version)
|
|
;
|
|
|
|
.export _exit
|
|
.export __STARTUP__ : absolute = 1 ; Mark as startup
|
|
|
|
.import initlib, donelib
|
|
.import moveinit, zerobss, callmain
|
|
.import BSOUT
|
|
.import __RAM_START__, __RAM_SIZE__ ; Linker generated
|
|
.import __STACKSIZE__ ; from configure file
|
|
.importzp ST
|
|
|
|
.include "zeropage.inc"
|
|
.include "c64.inc"
|
|
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Startup code
|
|
|
|
.segment "STARTUP"
|
|
|
|
Start:
|
|
|
|
; Switch to the second charset.
|
|
|
|
lda #14
|
|
jsr BSOUT
|
|
|
|
; Switch off the BASIC ROM.
|
|
|
|
lda $01
|
|
sta mmusave ; Save the memory configuration
|
|
and #$F8
|
|
ora #$06 ; Enable Kernal+I/O, disable BASIC
|
|
sta $01
|
|
|
|
tsx
|
|
stx spsave ; Save the system stack ptr
|
|
|
|
; Allow some re-entrancy by skipping the next task if it already was done.
|
|
; This sometimes can let us rerun the program without reloading it.
|
|
|
|
ldx move_init
|
|
beq L0
|
|
|
|
; Move the INIT segment from where it was loaded (over ZPSAVE and BSS)
|
|
; into where it must be run (in the heap).
|
|
|
|
jsr moveinit
|
|
dec move_init ; set to false
|
|
|
|
; Save space by putting the rest of the start-up code in the INIT segment,
|
|
; which can be re-used by the heap and the C stack.
|
|
|
|
L0: jsr initstart
|
|
|
|
; Back from main() [this is also the exit() entry]. Run the module destructors.
|
|
|
|
_exit: pha ; Save the return code on stack
|
|
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 BASIC's status variable.
|
|
|
|
pla
|
|
sta ST
|
|
|
|
; Restore the system stuff.
|
|
|
|
ldx spsave
|
|
txs ; Restore stack pointer
|
|
ldx mmusave
|
|
stx $01 ; Restore memory configuration
|
|
|
|
; Back to BASIC.
|
|
|
|
rts
|
|
|
|
|
|
; ------------------------------------------------------------------------
|
|
|
|
.segment "INIT"
|
|
|
|
initstart:
|
|
|
|
; Save the zero-page locations that we need.
|
|
|
|
ldx #zpspace-1
|
|
L1: lda sp,x
|
|
sta zpsave,x
|
|
dex
|
|
bpl L1
|
|
|
|
; Clear the BSS data.
|
|
|
|
jsr zerobss
|
|
|
|
; Set up the stack.
|
|
|
|
lda #<(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
|
|
ldx #>(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
|
|
sta sp
|
|
stx sp+1 ; Set argument stack ptr
|
|
|
|
; Call the module constructors.
|
|
|
|
jsr initlib
|
|
|
|
; Push the command-line arguments; and, call main().
|
|
|
|
jmp callmain
|
|
|
|
|
|
; ------------------------------------------------------------------------
|
|
; Data
|
|
|
|
.data
|
|
|
|
; These two variables were moved out of the BSS segment, and into DATA, because
|
|
; we need to use them before INIT is moved off of BSS, and before BSS is zeroed.
|
|
|
|
mmusave:.res 1
|
|
spsave: .res 1
|
|
|
|
move_init:
|
|
.byte 1
|
|
|
|
.segment "ZPSAVE"
|
|
|
|
zpsave: .res zpspace
|