;
; Startup code for cc65 (C128 version)
;
-; This must be the *first* file on the linker command line
-;
-
- .export _exit
- .export BRKStub, BRKOld, BRKInd
- .import condes, initlib, donelib
- .import initconio, doneconio, zerobss
- .import push0, _main
- .import __IRQFUNC_TABLE__, __IRQFUNC_COUNT__
- .import __RAM_START__, __RAM_SIZE__
-
- .include "zeropage.inc"
- .include "c128.inc"
- .include "../cbm/cbm.inc"
-
-; ------------------------------------------------------------------------
-; Constants
-
-IRQInd = $2FD ; JMP $0000 - used as indirect IRQ vector
-
-; ------------------------------------------------------------------------
-; Place the startup code in a special segment to cope with the quirks of
-; c128 banking. Do also create an empty segment named "NMI" to avoid
-; warnings if the rs232 routines are not used.
-.segment "NMI"
-; empty
+ .export _exit
+ .export __STARTUP__ : absolute = 1 ; Mark as startup
+ .import initlib, donelib
+ .import zerobss
+ .import push0, callmain
+ .import RESTOR, BSOUT, CLRCH
+ .import __RAM_START__, __RAM_SIZE__, __STACKSIZE__
+ .importzp ST
-.segment "STARTUP"
+ .include "zeropage.inc"
+ .include "c128.inc"
-; ------------------------------------------------------------------------
-; BASIC header with a SYS call
-
- .org $1BFF
- .word Head ; Load address
-Head: .word @Next
- .word 1000 ; Line number
- .byte $9E,"7181" ; SYS 7181
- .byte $00 ; End of BASIC line
-@Next: .word 0 ; BASIC end marker
- .reloc
; ------------------------------------------------------------------------
-; Actual code
+; Startup code
-; Close open files
+.segment "STARTUP"
- jsr CLRCH
+Start:
; Switch to the second charset
- lda #14
- jsr BSOUT
-
-; Set the bank for the file name our execution bank
-
- lda #0
- sta FNAM_BANK
+ lda #14
+ jsr BSOUT
; Before doing anything else, we have to setup our banking configuration.
; Otherwise just the lowest 16K are actually RAM. Writing through the ROM
; to the underlying RAM works, but it is bad style.
- lda MMU_CR ; Get current memory configuration...
- pha ; ...and save it for later
- lda #CC65_MMU_CFG ; Bank0 with kernal ROM
- sta MMU_CR
+ lda MMU_CR ; Get current memory configuration...
+ pha ; ...and save it for later
+ lda #MMU_CFG_CC65 ; Bank0 with kernal ROM
+ sta MMU_CR
; Save the zero page locations we need
- ldx #zpspace-1
-L1: lda sp,x
- sta zpsave,x
- dex
- bpl L1
+ ldx #zpspace-1
+L1: lda sp,x
+ sta zpsave,x
+ dex
+ bpl L1
; Clear the BSS data
pla ; Get MMU setting
sta mmusave
- tsx
- stx spsave ; Save the system stack pointer
+ tsx
+ stx spsave ; Save the system stack pointer
- lda #<(__RAM_START__ + __RAM_SIZE__)
+ lda #<(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
sta sp
- lda #>(__RAM_START__ + __RAM_SIZE__)
- sta sp+1 ; Set argument stack ptr
+ lda #>(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
+ sta sp+1 ; Set argument stack ptr
; Call module constructors
jsr initlib
-; Initialize conio stuff
-
- jsr initconio
-
-; If we have IRQ functions, chain our stub into the IRQ vector
-
- lda #<__IRQFUNC_COUNT__
- beq NoIRQ1
- lda IRQVec
- ldx IRQVec+1
- sta IRQInd+1
- stx IRQInd+2
- lda #<IRQStub
- ldx #>IRQStub
- sei
- sta IRQVec
- stx IRQVec+1
- cli
+; Set the bank for the file name to our execution bank. We must do this,
+; *after* calling constructors, because some of them may depend on the
+; original value of this register.
-; Pass an empty command line
+ lda #0
+ sta FNAM_BANK
-NoIRQ1: jsr push0 ; argc
- jsr push0 ; argv
+; Push arguments and call main()
- ldy #4 ; Argument size
- jsr _main ; call the users code
+ jsr callmain
-; This is also the _exit entry. Reset the IRQ vector if we chained it.
+; Back from main (this is also the _exit entry). Run module destructors
-_exit: lda #<__IRQFUNC_COUNT__
- beq NoIRQ2
- lda IRQInd+1
- ldx IRQInd+2
- sei
- sta IRQVec
- stx IRQVec+1
- cli
-
-; Run module destructors
-
-NoIRQ2: jsr donelib
-
-; Reset the conio stuff
-
- jsr doneconio
-
-; Reset the stack
-
- ldx spsave
- txs
+_exit: pha ; Save the return code on stack
+ jsr donelib
; Copy back the zero page stuff
- ldx #zpspace-1
+ ldx #zpspace-1
L2: lda zpsave,x
- sta sp,x
- dex
- bpl L2
+ sta sp,x
+ dex
+ bpl L2
-; Reset the memory configuration
+; Place the program return code into ST
- lda mmusave
- sta MMU_CR
+ pla
+ sta ST
-; Done, restore kernal vectors in an attempt to cleanup
+; Reset the stack and the memory configuration
- jmp RESTOR
+ ldx spsave
+ txs
+ ldx mmusave
+ stx MMU_CR
-; ------------------------------------------------------------------------
-; The C128 has ROM parallel to the RAM starting from $4000. The startup code
-; above will change this setting so that we have RAM from $0000-$BFFF. This
-; works quite well with the exception of interrupts: The interrupt handler
-; is in ROM, and the ROM switches back to the ROM configuration, which means
-; that parts of our program may not be accessible. Since the crt0 module is
-; the first module in the program, it will always be below $4000 and always
-; in RAM. So we place several short stubs here that switch back our ROM
-; config before calling our user defined handlers. These stubs are only
-; used if any other code uses the interrupt or break vectors. They are dead
-; code otherwise, but since there is no other way to keep them in low memory,
-; they have to go here.
-
-IRQStub:
- cld ; Just to be sure
- lda MMU_CR ; Get old register value
- pha ; And save on stack
- lda #CC65_MMU_CFG ; Bank 0 with kernal ROM
- sta MMU_CR
- ldy #<(__IRQFUNC_COUNT__*2)
- lda #<__IRQFUNC_TABLE__
- ldx #>__IRQFUNC_TABLE__
- jsr condes ; Call the functions
- pla ; Get old register value
- sta MMU_CR
- jmp IRQInd ; Jump to the save IRQ vector
-
-
-BRKStub:
- pla ; Get original MMU_CR value
- sta MMU_CR ; And set it
- jmp BRKInd ; Jump indirect to break
+; Done, return to BASIC
+ rts
; ------------------------------------------------------------------------
; Data
-.data
-zpsave: .res zpspace
+.segment "ZPSAVE"
-; Old break vector preceeded by a jump opcode
-BRKOld: jmp $0000
+zpsave: .res zpspace
-; Indirect vectors preceeded by a jump opcode
-BRKInd: jmp $0000
+; ------------------------------------------------------------------------
.bss
+
spsave: .res 1
mmusave:.res 1
-
-
-
projects / cc65 / blobdiff