Complete redesign of the CBM610 support.
Use wrappers to call the kernal in bank 15 instead of implementing kernal functionality within the cc65 libs (eats performance but is much smaller and simpler). Improved startup/shutdown code allows a return to the system bank without calling the BASIC cold start vector. git-svn-id: svn://svn.cc65.org/cc65/trunk@2793 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
cuz
@@ -4,17 +4,16 @@
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; This must be the *first* file on the linker command line
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;
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.export _exit
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.exportzp crtc, sid, IPCcia, cia, acia, tpi1, tpi2, ktab1
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.exportzp ktab2, ktab3, ktab4, time, RecvBuf, SendBuf
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.export _exit, BRKVec, UDTIM
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.import initlib, donelib
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.import condes, initlib, donelib
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.import push0, callmain
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.import __BSS_RUN__, __BSS_SIZE__
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.import irq, nmi
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.import k_irq, k_nmi
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.import __BSS_RUN__, __BSS_SIZE__, __EXTZP_RUN__
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.import __IRQFUNC_TABLE__, __IRQFUNC_COUNT__
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.import SCNKEY
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.include "zeropage.inc"
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.include "extzp.inc"
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.include "cbm610.inc"
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@@ -47,51 +46,31 @@
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; that is overwritten later.
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;
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.code
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.segment "BASICHDR"
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; To make things more simple, make the code of this module absolute.
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.org $0001
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Head: .byte $03,$00,$11,$00,$0a,$00,$81,$20,$49,$b2,$30,$20,$a4,$20,$34,$00
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.byte $03,$00,$11,$00,$0a,$00,$81,$20,$49,$b2,$30,$20,$a4,$20,$34,$00
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.byte $19,$00,$14,$00,$87,$20,$4a,$00,$27,$00,$1e,$00,$97,$20,$32,$35
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.byte $36,$aa,$49,$2c,$4a,$00,$2f,$00,$28,$00,$82,$20,$49,$00,$39,$00
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.byte $32,$00,$9e,$20,$32,$35,$36,$00,$4f,$00,$3c,$00,$83,$20,$31,$32
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.byte $30,$2c,$31,$36,$39,$2c,$31,$2c,$31,$33,$33,$2c,$30,$00,$00,$00
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; Since we need some vectors to access stuff in the system bank for our own,
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; we will include them here, starting from $60:
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.res $60-*
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crtc: .word $d800
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sid: .word $da00
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IPCcia: .word $db00
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cia: .word $dc00
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acia: .word $dd00
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tpi1: .word $de00
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tpi2: .word $df00
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ktab1: .word $ea29
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ktab2: .word $ea89
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ktab3: .word $eae9
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ktab4: .word $eb49
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time: .dword $0000
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RecvBuf: .word $0100 ; RS232 received buffer
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SendBuf: .word $0200 ; RS232 send buffer
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;------------------------------------------------------------------------------
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; The code in the target bank when switching back will be put at the bottom
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; of the stack. We will jump here to switch segments. The range $F2..$FF is
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; not used by any kernal routine.
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.res $F8-*
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Back: ldx spsave
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.segment "STARTUP"
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Back: sei
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ldx spsave
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txs
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lda IndReg
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sta ExecReg
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; The following code is a copy of the code that is poked in the system bank
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; memory by the basic header program, it's only for documentation and not
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; actually used here:
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;------------------------------------------------------------------------------
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; We are at $100 now. The following snippet is a copy of the code that is poked
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; in the system bank memory by the basic header program, it's only for
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; documentation and not actually used here:
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sei
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lda #$01
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@@ -99,57 +78,132 @@ Back: ldx spsave
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; This is the actual starting point of our code after switching banks for
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; startup. Beware: The following code will get overwritten as soon as we
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; use the stack (since it's in page 1)!
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; use the stack (since it's in page 1)! We jump to another location, since
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; we need some space for subroutines that aren't used later.
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tsx
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stx spsave ; Save the system stackpointer
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ldx #$FF
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txs ; Set up our own stack
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jmp Origin
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; Hardware vectors, copied to $FFFA
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.proc vectors
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sta ExecReg
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rts
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nop
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.word nmi ; NMI vector
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.word 0 ; Reset - not used
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.word irq ; IRQ vector
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.endproc
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; Initializers for the extended zeropage. See extzp.s
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.proc extzp
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.word $0100 ; sysp1
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.word $0300 ; sysp3
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.word $d800 ; crtc
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.word $da00 ; sid
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.word $db00 ; ipccia
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.word $dc00 ; cia
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.word $dd00 ; acia
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.word $de00 ; tpi1
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.word $df00 ; tpi2
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.word $ea29 ; ktab1
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.word $ea89 ; ktab2
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.word $eae9 ; ktab3
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.word $eb49 ; ktab4
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.endproc
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; The following code is part of the kernal call subroutine. It is copied
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; to $FFAE
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.proc callsysbank_15
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php
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pha
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lda #$0F ; Bank 15
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sta IndReg
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sei
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.endproc
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; Save the old stack pointer from the system bank and setup our hw sp
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Origin: tsx
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stx spsave ; Save the system stackpointer
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ldx #$FE ; Leave $1FF untouched for cross bank calls
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txs ; Set up our own stack
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; Initialize the extended zeropage
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ldx #.sizeof(extzp)-1
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L1: lda extzp,x
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sta <__EXTZP_RUN__,x
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dex
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bpl L1
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; Set the interrupt, NMI and other vectors
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ldy #vectors_size-1
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L0: lda vectors,y
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sta $10000 - vectors_size,y
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ldy #.sizeof(vectors)-1
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L2: lda vectors,y
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sta $10000 - .sizeof(vectors),y
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dey
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bpl L0
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bpl L2
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; Switch the indirect segment to the system bank
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lda #$0F
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sta IndReg
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; Copy the kernal zero page ($90-$F2) from the system bank
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; Setup the C stack
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lda #$90
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sta ptr1
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lda #$00
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sta ptr1+1
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ldy #$62-1
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L1: lda (ptr1),y
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sta $90,y
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dey
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bpl L1
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lda #.lobyte($FEB5 - .sizeof(callsysbank_15))
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sta sp
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lda #.hibyte($FEB5 - .sizeof(callsysbank_15))
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sta sp+1
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; Copy the page 3 vectors in place
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; Setup the subroutine and jump vector table that redirects kernal calls to
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; the system bank. Copy the bank switch routines starting at $FEB5 from the
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; system bank into the current bank.
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ldy #$00
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L2: lda p3vectors,y
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sta $300,y
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iny
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cpy #p3vectors_size
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bne L2
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; Copy the rest of page 3 from the system bank
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ldy #.sizeof(callsysbank_15)-1 ; Copy the modified part
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@L1: lda callsysbank_15,y
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sta $FEB5 - .sizeof(callsysbank_15),y
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dey
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bpl @L1
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lda #$00
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sta ptr1
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lda #$03
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sta ptr1+1
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L3: lda (ptr1),y
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sta $300,y
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iny
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bne L3
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lda #.lobyte($FEB5) ; Copy the ROM part
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sta ptr1
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lda #.hibyte($FEB5)
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sta ptr1+1
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ldy #$00
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@L2: lda (ptr1),y
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sta $FEB5,y
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iny
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cpy #<($FF6F-$FEB5)
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bne @L2
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; Setup the jump vector table
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ldy #$00
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ldx #45-1 ; Number of vectors
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@L3: lda #$20 ; JSR opcode
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sta $FF6F,y
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iny
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lda #.lobyte($FEB5 - .sizeof(callsysbank_15))
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sta $FF6F,y
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iny
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lda #.hibyte($FEB5 - .sizeof(callsysbank_15))
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sta $FF6F,y
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iny
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dex
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bpl @L3
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; Copy the stack from the system bank into page 3
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ldy #$FF
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L4: lda (sysp1),y
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sta $300,y
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dey
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cpy spsave
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bne L4
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; Set the indirect segment to bank we're executing in
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@@ -186,64 +240,19 @@ Z3: sta (ptr1),y
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iny
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dex
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bne Z3
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Z4:
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; Setup the C stack
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lda #<$FF81
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sta sp
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lda #>$FF81
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sta sp+1
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; We expect to be in page 2 now
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.if (* < $1FD)
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jmp $200
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.res $200-*
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.endif
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.if (* < $200)
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.res $200-*,$EA
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.endif
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.if (* >= $2F0)
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.error "Code range invalid"
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.endif
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; This code is in page 2, so we may now start calling subroutines safely,
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; since the code we execute is no longer in the stack page.
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; Call module constructors
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jsr initlib
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; Execute the program code
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jmp Start
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Z4: jmp Init
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; ------------------------------------------------------------------------
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; Additional data that we need for initialization and that's overwritten
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; later
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; We are at $200 now. We may now start calling subroutines safely, since
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; the code we execute is no longer in the stack page.
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vectors:
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sta ExecReg
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rts
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.byte $01 ; Filler
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.word nmi
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.word 0 ; Reset - not used
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.word irq
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vectors_size = * - vectors
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.segment "PAGE2"
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p3vectors:
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.word k_irq ; IRQ user vector
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.word k_brk ; BRK user vector
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.word k_nmi ; NMI user vector
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p3vectors_size = * - p3vectors
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; Call module constructors, enable chained IRQs afterwards.
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; ------------------------------------------------------------------------
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; This is the program code after setup. It starts at $400
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.res $400-*
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Start:
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Init: jsr initlib
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lda #.lobyte(__IRQFUNC_COUNT__*2)
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sta irqcount
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; Enable interrupts
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@@ -253,51 +262,140 @@ Start:
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jsr callmain
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; Call module destructors. This is also the _exit entry.
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; Disable Call module destructors. This is also the _exit entry and the default entry
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; point for the break vector.
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_exit: jsr donelib ; Run module destructors
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_exit: lda #$00
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sta irqcount ; Disable custom irq handlers
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jsr donelib ; Run module destructors
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; Clear the start of the zero page, since it will be interpreted as a
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; (garbage) BASIC program otherwise. This is also the default entry for
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; the break vector.
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; Adress the system bank
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k_brk: sei
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lda #$00
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ldx #$3E
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Clear: sta $02,x
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dex
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bne Clear
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lda #$0F
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sta IndReg
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; Setup the welcome code at the stack bottom in the system bank. Use
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; the F4/F5 vector to access the system bank
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; Copy back the old system bank stack contents
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lda #$0F
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sta IndReg
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ldy #$00
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sty $F4
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iny
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sty $F5
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ldy #reset_size-1
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@L1: lda reset,y
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sta ($F4),y
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dey
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bne @L1
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jmp Back
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ldy #$FF
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@L1: lda $300,y
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sta (sysp1),y
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dey
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cpy spsave
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bne @L1
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; ------------------------------------------------------------------------
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; Code that is copied into the system bank at $100 when switching back
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; Setup the welcome code at the stack bottom in the system bank.
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reset: cli
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jmp $8000 ; BASIC cold start
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reset_size = * - reset
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ldy #$00
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lda #$58 ; CLI opcode
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sta (sysp1),y
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iny
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lda #$60 ; RTS opcode
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sta (sysp1),y
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jmp Back
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; -------------------------------------------------------------------------
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; Data area - switch back to relocatable mode
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; The IRQ handler goes into PAGE2. For performance reasons, and to allow
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; easier chaining, we do handle the IRQs in the execution bank (instead of
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; passing them to the system bank).
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.reloc
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; This is the mapping of the active irq register of the 6525 (tpi1):
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;
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; Bit 7 6 5 4 3 2 1 0
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; | | | | ^ 50 Hz
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; | | | ^ SRQ IEEE 488
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; | | ^ cia
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; | ^ IRQB ext. Port
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; ^ acia
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irq: pha
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txa
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pha
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tya
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pha
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lda IndReg
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pha
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lda ExecReg
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sta IndReg ; Be sure to address our segment
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tsx
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lda $105,x ; Get the flags from the stack
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and #$10 ; Test break flag
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bne dobrk
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; It's an IRQ
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cld
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; Call chained IRQ handlers
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ldy irqcount
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beq irqskip
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lda #<__IRQFUNC_TABLE__
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ldx #>__IRQFUNC_TABLE__
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jsr condes ; Call the functions
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; Done with chained IRQ handlers, check the TPI for IRQs and handle them
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irqskip:lda #$0F
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sta IndReg
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ldy #TPI::AIR
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lda (tpi1),y ; Interrupt Register 6525
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beq noirq
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; 50/60Hz interrupt
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cmp #%00000001 ; ticker irq?
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bne irqend
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jsr SCNKEY ; Poll the keyboard
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jsr UDTIM ; Bump the time
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; Done
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irqend: ldy #TPI::AIR
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sta (tpi1),y ; Clear interrupt
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noirq: pla
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sta IndReg
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pla
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tay
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pla
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tax
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pla
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nmi: rti
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dobrk: jmp (BRKVec)
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; -------------------------------------------------------------------------
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; udtim routine for the 610. We will not check for the stop key here, since
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; C programs will not use it.
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;
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.proc UDTIM
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inc time
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bne L9
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inc time+1
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bne L9
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inc time+2
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bne L9
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inc time+3
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L9: rts
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.endproc
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; -------------------------------------------------------------------------
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; Page 3
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.segment "PAGE3"
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BRKVec: .addr _exit ; BRK indirect vector
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; -------------------------------------------------------------------------
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; Data area.
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.data
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spsave: .res 1
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.bss
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irqcount: .byte 0
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