54 lines
1.8 KiB
ArmAsm
54 lines
1.8 KiB
ArmAsm
; ---------------------------------------------------------------------------
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; crt0.s
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; ---------------------------------------------------------------------------
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;
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; Startup code for cc65 (Single Board Computer version)
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.export _init, _exit
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.import _main, _cputc
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.export __STARTUP__ : absolute = 1 ; Mark as startup
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.import __STACKSTART__, __STACKSIZE__ ; Linker generated
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.import copydata, zerobss, initlib, donelib
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.include "zeropage.inc"
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; ---------------------------------------------------------------------------
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; Place the startup code in a special segment
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.segment "STARTUP"
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; ---------------------------------------------------------------------------
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; A little light 6502 housekeeping
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_init: LDX #$FF ; Initialize stack pointer to $01FF
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TXS
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CLD ; Clear decimal mode
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; ---------------------------------------------------------------------------
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; Set cc65 argument stack pointer
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LDA #<(__STACKSTART__ + __STACKSIZE__)
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STA sp
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LDA #>(__STACKSTART__ + __STACKSIZE__)
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STA sp+1
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; ---------------------------------------------------------------------------
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; Initialize memory storage
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; JSR zerobss ; Clear BSS segment (this fails)
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; JSR copydata ; Initialize DATA segment (this also fails. but prints something)
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JSR initlib ; Run constructors (This one works)
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; ---------------------------------------------------------------------------
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; Call main()
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cli
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JSR _main
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; ---------------------------------------------------------------------------
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; Back from main (this is also the _exit entry): force a software break
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_exit: JSR donelib ; Run destructors
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BRK
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