;
; 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__
+ .export __STARTUP__ : absolute = 1 ; Mark as startup
+ .import callirq, initlib, donelib
+ .import zerobss
+ .import push0, callmain
+ .import RESTOR, BSOUT, CLRCH
+ .import __INTERRUPTOR_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
; ------------------------------------------------------------------------
-; 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
+; c128 banking.
.segment "STARTUP"
-; ------------------------------------------------------------------------
; BASIC header with a SYS call
.org $1BFF
.word Head ; Load address
Head: .word @Next
- .word 1000 ; Line number
+ .word .version ; Line number
.byte $9E,"7181" ; SYS 7181
.byte $00 ; End of BASIC line
@Next: .word 0 ; BASIC end marker
; ------------------------------------------------------------------------
; Actual code
- ldx #zpspace-1
-L1: lda sp,x
- sta zpsave,x ; save the zero page locations we need
- dex
- bpl L1
-
; Close open files
jsr CLRCH
-; Switch to second charset
+; Switch to the second charset
lda #14
jsr BSOUT
-; Get the current MMU setting and save it. Set new memory config.
+; 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
+ 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
+
; Clear the BSS data
jsr zerobss
sta mmusave
tsx
- stx spsave ; save system stk ptr
+ stx spsave ; Save the system stack pointer
lda #<(__RAM_START__ + __RAM_SIZE__)
sta sp
lda #>(__RAM_START__ + __RAM_SIZE__)
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__
+ lda #<__INTERRUPTOR_COUNT__
beq NoIRQ1
lda IRQVec
ldx IRQVec+1
stx IRQVec+1
cli
-; Pass an empty command line
+; Call module constructors
+
+NoIRQ1: jsr initlib
-NoIRQ1: jsr push0 ; argc
- jsr push0 ; argv
+; 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.
- ldy #4 ; Argument size
- jsr _main ; call the users code
+ lda #0
+ sta FNAM_BANK
-; This is also the _exit entry. Reset the IRQ vector if we chained it.
+; Push arguments and call main()
-_exit: lda #<__IRQFUNC_COUNT__
+ jsr callmain
+
+; Back from main (this is also the _exit entry). Run module destructors
+
+_exit: jsr donelib
+
+; Reset the IRQ vector if we chained it.
+
+ pha ; Save the return code on stack
+ lda #<__INTERRUPTOR_COUNT__
beq NoIRQ2
lda IRQInd+1
ldx IRQInd+2
stx IRQVec+1
cli
-; Run module destructors
+; Copy back the zero page stuff
-NoIRQ2: jsr donelib
+NoIRQ2: ldx #zpspace-1
+L2: lda zpsave,x
+ sta sp,x
+ dex
+ bpl L2
-; Reset the conio stuff
+; Place the program return code into ST
- jsr doneconio
+ pla
+ sta ST
-; Reset stack and the MMU
+; Reset the stack and the memory configuration
ldx spsave
txs
- lda mmusave
- sta MMU_CR
-
-; Copy back the zero page stuff
+ ldx mmusave
+ stx MMU_CR
- ldx #zpspace-1
-L2: lda zpsave,x
- sta sp,x
- dex
- bpl L2
-
-; Done
+; Done, restore kernal vectors in an attempt to cleanup
jmp RESTOR
; 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.
+; that parts of our program may not be accessible. To solve this, we place
+; the following code into a special segment called "LOWCODE" which will be
+; placed just above the startup code, so it goes into a RAM area that is
+; not banked.
+
+.segment "LOWCODE"
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
+ cld ; Just to be sure
+ lda MMU_CR ; Get old register value
+ pha ; And save on stack
+ lda #MMU_CFG_CC65 ; Bank 0 with kernal ROM
sta MMU_CR
- ldy #<(__IRQFUNC_COUNT__*2)
- lda #<__IRQFUNC_TABLE__
- ldx #>__IRQFUNC_TABLE__
- jsr condes ; Call the functions
+ jsr callirq ; 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
+ jmp IRQInd ; Jump to the saved IRQ vector
; ------------------------------------------------------------------------
; Data
-.data
-zpsave: .res zpspace
+.segment "ZPSAVE"
-; Old break vector preceeded by a jump opcode
-BRKOld: jmp $0000
-
-; Indirect vectors preceeded by a jump opcode
-BRKInd: jmp $0000
+zpsave: .res zpspace
.bss
spsave: .res 1
projects / cc65 / blobdiff