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https://github.com/cc65/cc65.git
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136 lines
2.4 KiB
ArmAsm
136 lines
2.4 KiB
ArmAsm
;
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; Startup code for cc65 (Plus/4 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, push0, doatexit, _main
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.import initconio, doneconio, zerobss
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.include "plus4.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 $0FFF
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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,"4109" ; SYS 4109
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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 system stk ptr
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sec
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jsr MEMTOP ; Get top memory
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cpy #$80 ; We can only use the low 32K :-(
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bcc MemOk
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ldy #$80
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ldx #$00
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MemOk: stx sp
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sty 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
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; Reset the conio stuff
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jsr doneconio
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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
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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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