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https://github.com/cc65/cc65.git
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139 lines
2.6 KiB
ArmAsm
139 lines
2.6 KiB
ArmAsm
;
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; Startup code for cc65 (C64 version)
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;
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; This must be the *first* file on the linker command line
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;
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.export _exit
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.import __hinit, initconio, zerobss, push0, doatexit
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.import _main
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.include "c64.inc"
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.include "../cbm/cbm.inc"
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; ------------------------------------------------------------------------
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; Define and export the ZP variables for the C64 runtime
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.exportzp sp, sreg, regsave
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.exportzp ptr1, ptr2, ptr3, ptr4
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.exportzp tmp1, tmp2, tmp3, tmp4
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.exportzp regbank, zpspace
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.zeropage
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zpstart = *
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sp: .res 2 ; Stack pointer
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sreg: .res 2 ; Secondary register/high 16 bit for longs
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regsave: .res 2 ; slot to save/restore (E)AX into
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ptr1: .res 2
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ptr2: .res 2
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ptr3: .res 2
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ptr4: .res 2
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tmp1: .res 1
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tmp2: .res 1
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tmp3: .res 1
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tmp4: .res 1
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regbank: .res 6 ; 6 byte register bank
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zpspace = * - zpstart ; Zero page space allocated
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.code
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; ------------------------------------------------------------------------
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; BASIC header with a SYS call
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.org $7FF
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.word Head ; Load address
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Head: .word @Next
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.word 1000 ; Line number
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.byte $9E,"2061" ; SYS 2061
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.byte $00 ; End of BASIC line
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@Next: .word 0 ; BASIC end marker
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.reloc
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; ------------------------------------------------------------------------
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; Actual code
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ldy #zpspace-1
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L1: lda sp,y
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sta zpsave,y ; Save the zero page locations we need
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dey
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bpl L1
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; Close open files
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jsr CLRCH
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; Switch to second charset
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lda #14
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jsr BSOUT
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; Clear the BSS data
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jsr zerobss
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; Save system stuff and setup the stack
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tsx
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stx spsave ; Save the system stack ptr
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lda $01
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sta mmusave ; Save the memory configuration
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lda $01
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and #$F8
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ora #$06 ; Enable kernal+I/O, disable basic
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sta $01
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lda #<$D000
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sta sp
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lda #>$D000
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sta sp+1 ; Set argument stack ptr
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; Initialize the heap
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jsr __hinit
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; Initialize conio stuff
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jsr initconio
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; Pass an empty command line
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jsr push0 ; argc
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jsr push0 ; argv
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ldy #4 ; Argument size
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jsr _main ; call the users code
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; fall thru to exit...
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_exit: jsr doatexit ; call exit functions
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ldx spsave
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txs ; Restore stack pointer
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lda mmusave
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sta $01 ; Restore memory configuration
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; Copy back the zero page stuff
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ldy #zpspace-1
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L2: lda zpsave,y
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sta sp,y
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dey
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bpl L2
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; Reset changed vectors, back to basic
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jmp RESTOR
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.data
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zpsave: .res zpspace
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.bss
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spsave: .res 1
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mmusave:.res 1
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