;
; 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 "c128.inc"
- .include "../cbm/cbm.inc"
-
-; ------------------------------------------------------------------------
-; Constants
-
-IRQInd = $2FD ; JMP $0000 - used as indirect IRQ vector
-
-; ------------------------------------------------------------------------
-; Define and export the ZP variables for the C64 runtime
-
- .exportzp sp, sreg, regsave
- .exportzp ptr1, ptr2, ptr3, ptr4
- .exportzp tmp1, tmp2, tmp3, tmp4
- .exportzp regbank, zpspace
-
-.zeropage
-
-zpstart = *
-sp: .res 2 ; Stack pointer
-sreg: .res 2 ; Secondary register/high 16 bit for longs
-regsave: .res 2 ; slot to save/restore (E)AX into
-ptr1: .res 2
-ptr2: .res 2
-ptr3: .res 2
-ptr4: .res 2
-tmp1: .res 1
-tmp2: .res 1
-tmp3: .res 1
-tmp4: .res 1
-regbank: .res 6 ; 6 byte register bank
-
-zpspace = * - zpstart ; Zero page space allocated
-
-; 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
-.segment "STARTUP"
+ .export _exit
+ .export __STARTUP__ : absolute = 1 ; Mark as startup
+ .import initlib, donelib
+ .import zerobss
+ .import push0, callmain
+ .import RESTOR, BSOUT, CLRCH
+ .import __MAIN_START__, __MAIN_SIZE__, __STACKSIZE__
+ .importzp ST
-; ------------------------------------------------------------------------
-; BASIC header with a SYS call
+ .include "zeropage.inc"
+ .include "c128.inc"
- .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
-
-; Close open files
-
- jsr CLRCH
-
-; Switch to the second charset
-
- 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
+; Startup code
-; Save the zero page locations we need
+.segment "STARTUP"
- ldx #zpspace-1
-L1: lda sp,x
- sta zpsave,x
- dex
- bpl L1
+Start:
-; Clear the BSS data
+; Switch to the second charset.
- jsr zerobss
+ lda #14
+ jsr BSOUT
-; Save system stuff and setup the stack
+; Before doing anything else, we have to set up 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.
- pla ; Get MMU setting
- sta mmusave
+ lda MMU_CR ; Get current memory configuration...
+ pha ; ...and save it for later
+ lda #MMU_CFG_CC65 ; Bank0 with Kernal ROM
+ sta MMU_CR
- tsx
- stx spsave ; Save the system stack pointer
+; Save the zero-page locations that we need.
- lda #<(__RAM_START__ + __RAM_SIZE__)
- sta sp
- lda #>(__RAM_START__ + __RAM_SIZE__)
- sta sp+1 ; Set argument stack ptr
+ ldx #zpspace-1
+L1: lda sp,x
+ sta zpsave,x
+ dex
+ bpl L1
-; Call module constructors
+; Clear the BSS data.
- jsr initlib
+ jsr zerobss
-; Initialize conio stuff
+; Save some system stuff; and, set up the stack.
- jsr initconio
+ pla ; Get MMU setting
+ sta mmusave
-; If we have IRQ functions, chain our stub into the IRQ vector
+ tsx
+ stx spsave ; Save the system stack pointer
- 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
+ lda #<(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
+ ldx #>(__MAIN_START__ + __MAIN_SIZE__ + __STACKSIZE__)
+ sta sp
+ stx sp+1 ; Set argument stack ptr
-; Pass an empty command line
+; Call the module constructors.
-NoIRQ1: jsr push0 ; argc
- jsr push0 ; argv
+ jsr initlib
- ldy #4 ; Argument size
- jsr _main ; call the users code
+; Set the bank for the file name to our execution bank. We must do this
+; *after* calling the constructors because some of them might depend on
+; the original value of this register.
-; This is also the _exit entry. Reset the IRQ vector if we chained it.
+ lda #0
+ sta FNAM_BANK
-_exit: lda #<__IRQFUNC_COUNT__
- beq NoIRQ2
- lda IRQInd+1
- ldx IRQInd+2
- sei
- sta IRQVec
- stx IRQVec+1
- cli
+; Push the command-line arguments; and, call main().
-; Run module destructors
+ jsr callmain
-NoIRQ2: jsr donelib
+; Back from main() [this is also the exit() entry]. Run the module destructors.
-; Reset the conio stuff
+_exit: pha ; Save the return code on stack
+ jsr donelib
- jsr doneconio
+; Copy back the zero-page stuff.
-; Reset the stack
+ ldx #zpspace-1
+L2: lda zpsave,x
+ sta sp,x
+ dex
+ bpl L2
- ldx spsave
- txs
+; Place the program return code into BASIC's status variable.
-; Copy back the zero page stuff
+ pla
+ sta ST
- ldx #zpspace-1
-L2: lda zpsave,x
- sta sp,x
- dex
- bpl L2
+; Reset the stack and the memory configuration.
-; Reset the memory configuration
+ ldx spsave
+ txs
+ ldx mmusave
+ stx MMU_CR
- lda mmusave
- sta MMU_CR
-
-; Done, restore kernal vectors in an attempt to cleanup
-
- jmp RESTOR
-
-; ------------------------------------------------------------------------
-; 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 "INIT"
-; 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
-
-
+spsave: .res 1
+mmusave:.res 1