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https://github.com/cc65/cc65.git
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99ecc9a609
separate module that contains a module constructor. In some cases, the code was even unnecessary, since the screen size is known in advance. git-svn-id: svn://svn.cc65.org/cc65/trunk@476 b7a2c559-68d2-44c3-8de9-860c34a00d81
131 lines
2.4 KiB
ArmAsm
131 lines
2.4 KiB
ArmAsm
;
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; Startup code for cc65 (PET 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 initlib, donelib
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.import zerobss, push0
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.import _main
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.include "pet.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 $3FF
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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,"1037" ; SYS 1037
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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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ldx #zpspace-1
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L1: lda sp,x
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sta zpsave,x ; Save the zero page locations we need
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dex
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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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; sta $E84C ; See PET FAQ
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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 MEMSIZE
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sta sp
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lda MEMSIZE+1
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sta sp+1 ; Set argument stack ptr
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; Call module constructors
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jsr initlib
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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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; Call module destructors. This is also the _exit entry.
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_exit: jsr donelib ; Run module destructors
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; Restore system stuff
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ldx spsave
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txs ; Restore stack pointer
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; Copy back the zero page stuff
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ldx #zpspace-1
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L2: lda zpsave,x
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sta sp,x
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dex
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bpl L2
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; Back to basic
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rts
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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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