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https://github.com/cc65/cc65.git
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d8c31cf1d3
The name RAM doesn't make much sense in general for a memeory area because i.e. the zero page is for sure RAM but is not part of the memory area named RAM. For disk based targets it makes sense to put the disk file more into focus and here MAIN means the main part of the file - in contrast to some header. Only for ROM based targets the name RAM is kept as it makes sense to focus on the difference between RAM and ROM.
98 lines
2.1 KiB
ArmAsm
98 lines
2.1 KiB
ArmAsm
;
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; Startup code for cc65 (Vic20 version)
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;
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.export _exit
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.export __STARTUP__ : absolute = 1 ; Mark as startup
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.import initlib, donelib
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.import zerobss, push0
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.import callmain
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.import RESTOR, BSOUT, CLRCH
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.import __MAIN_START__, __MAIN_SIZE__ ; Linker generated
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.import __STACKSIZE__ ; Linker generated
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.importzp ST
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.include "zeropage.inc"
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.include "vic20.inc"
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; ------------------------------------------------------------------------
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; Startup code
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.segment "STARTUP"
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Start:
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; Save the zero-page locations that we need.
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ldx #zpspace-1
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L1: lda sp,x
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sta zpsave,x
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dex
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bpl L1
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; Switch to the 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 some system stuff; and, set up the stack.
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tsx
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stx spsave ; Save the system stack ptr
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lda #<(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
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ldx #>(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
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sta sp
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stx sp+1 ; Set argument stack ptr
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; Call the module constructors.
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jsr initlib
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; Push the command-line arguments; and, call main().
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jsr callmain
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; Back from main() [this is also the exit() entry]. Run the module destructors.
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_exit: pha ; Save the return code on stack
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jsr donelib
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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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; Place the program return code into BASIC's status variable.
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pla
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sta ST
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; Restore the stack pointer.
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ldx spsave
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txs
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; Back to BASIC.
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rts
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; ------------------------------------------------------------------------
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.segment "INIT"
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zpsave: .res zpspace
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; ------------------------------------------------------------------------
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.bss
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spsave: .res 1
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