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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.
121 lines
2.8 KiB
ArmAsm
121 lines
2.8 KiB
ArmAsm
;
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; Startup code for cc65 (C128 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
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.import push0, callmain
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.import RESTOR, BSOUT, CLRCH
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.import __MAIN_START__, __MAIN_SIZE__, __STACKSIZE__
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.importzp ST
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.include "zeropage.inc"
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.include "c128.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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; Switch to the second charset.
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lda #14
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jsr BSOUT
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; Before doing anything else, we have to set up our banking configuration.
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; Otherwise, just the lowest 16K are actually RAM. Writing through the ROM
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; to the underlying RAM works; but, it is bad style.
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lda MMU_CR ; Get current memory configuration...
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pha ; ...and save it for later
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lda #MMU_CFG_CC65 ; Bank0 with Kernal ROM
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sta MMU_CR
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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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; 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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pla ; Get MMU setting
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sta mmusave
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tsx
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stx spsave ; Save the system stack pointer
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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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; Set the bank for the file name to our execution bank. We must do this
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; *after* calling the constructors because some of them might depend on
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; the original value of this register.
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lda #0
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sta FNAM_BANK
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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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; Reset the stack and the memory configuration.
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ldx spsave
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txs
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ldx mmusave
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stx MMU_CR
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; Done, return to BASIC.
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rts
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; ------------------------------------------------------------------------
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; Data
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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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mmusave:.res 1
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