Redesigned the IRQ and BREAK logic, debugged the mouse routines

git-svn-id: svn://svn.cc65.org/cc65/trunk@898 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/c128/crt0.s

@@ -4,13 +4,22 @@
 ; This must be the *first* file on the linker command line
 ;
 
-	.export		_exit
-	.import		initlib, donelib
-	.import	     	initconio, doneconio, zerobss
-	.import		push0, _main
+    	.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"
+    	.include 	"c128.inc"
+	.include 	"../cbm/cbm.inc"
+
+; ------------------------------------------------------------------------
+; Constants
+
+CC65_MMU_CFG	= $0E	; Bank 0 with kernal ROM
+IRQInd		= $2FD	; JMP $0000 - used as indirect IRQ vector
 
 ; ------------------------------------------------------------------------
 ; Define and export the ZP variables for the C64 runtime
@@ -74,8 +83,8 @@ L1:	lda    	sp,x
 
 	lda	MMU_CR	 	; Get current memory configuration...
        	pha		 	; ...and save it for later
-	lda	#$0E	 	; Bank0 with kernal ROM
-	sta	MMU_CR
+       	lda    	#CC65_MMU_CFG	; Bank0 with kernal ROM
+    	sta	MMU_CR
 
 ; Clear the BSS data
 
@@ -89,10 +98,10 @@ L1:	lda    	sp,x
        	tsx
        	stx    	spsave	 	; save system stk ptr
 
- 	lda    	#<$C000
- 	sta	sp
-	lda	#>$C000
- 	sta    	sp+1
+	lda    	#<(__RAM_START__ + __RAM_SIZE__)
+	sta	sp
+	lda	#>(__RAM_START__ + __RAM_SIZE__)
+       	sta	sp+1   		; Set argument stack ptr
 
 ; Call module constructors
 
@@ -102,17 +111,43 @@ L1:	lda    	sp,x
 
 	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
+
 ; Pass an empty command line
 
- 	jsr	push0	 	; argc
- 	jsr	push0	 	; argv
+NoIRQ1:	jsr	push0 	 	; argc
+ 	jsr	push0 	 	; argv
 
  	ldy	#4    	 	; Argument size
        	jsr    	_main 	 	; call the users code
 
-; Call module destructors. This is also the _exit entry.
+; This is also the _exit entry. Reset the IRQ vector if we chained it.
 
-_exit:	jsr	donelib		; 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
 
@@ -120,9 +155,9 @@ _exit:	jsr	donelib		; Run module destructors
 
 ; Reset stack and the MMU
 
-	ldx    	spsave 	 	; Patched at runtime
+	ldx    	spsave
  	txs
-       	lda    	mmusave	 	; Patched at runtime
+       	lda    	mmusave
 	sta	MMU_CR
 
 ; Copy back the zero page stuff
@@ -137,9 +172,52 @@ L2:	lda	zpsave,x
 
      	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
+
+
+; ------------------------------------------------------------------------
+; Data
+
 .data
 zpsave:	.res	zpspace
 
+; Old break vector preceeded by a jump opcode
+BRKOld: jmp     $0000
+
+; Indirect vectors preceeded by a jump opcode
+BRKInd: jmp     $0000
+
 .bss
 spsave:	.res	1
 mmusave:.res	1