From 463712217c7cfa64414da8d964fb24de0e7e78cd Mon Sep 17 00:00:00 2001
From: cuz <cuz@b7a2c559-68d2-44c3-8de9-860c34a00d81>
Date: Tue, 26 Oct 2004 19:44:30 +0000
Subject: [PATCH] Add interrupt handling code from Stefan Haubenthal

git-svn-id: svn://svn.cc65.org/cc65/trunk@3264 b7a2c559-68d2-44c3-8de9-860c34a00d81
---
 libsrc/vic20/crt0.s | 48 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 42 insertions(+), 6 deletions(-)

diff --git a/libsrc/vic20/crt0.s b/libsrc/vic20/crt0.s
index a0425cee7..81a9c025d 100644
--- a/libsrc/vic20/crt0.s
+++ b/libsrc/vic20/crt0.s
@@ -5,15 +5,15 @@
 ;
 
 	.export		_exit
-	.import		initlib, donelib
+	.import		initlib, donelib, callirq
        	.import	       	zerobss, push0
 	.import	     	callmain
         .import         RESTOR, BSOUT, CLRCH
+	.import	       	__IRQFUNC_COUNT__
      	.import		__RAM_START__, __RAM_SIZE__	; Linker generated
 
         .include        "zeropage.inc"
      	.include     	"vic20.inc"
-     	.include     	"../cbm/cbm.inc"
 
 ; ------------------------------------------------------------------------
 ; Place the startup code in a special segment.
@@ -70,14 +70,41 @@ L1:	lda	sp,x
 
 	jsr	initlib
 
+; 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
+
 ; Push arguments and call main()
 
-       	jsr    	callmain
+NoIRQ1: jsr     callmain
+
+; Back from main (This is also the _exit entry). Reset the IRQ vector if we
+; chained it.
+
+_exit: 	pha  			; Save the return code on stack
+	lda     #<__IRQFUNC_COUNT__
+	beq	NoIRQ2
+	lda	IRQInd+1
+	ldx	IRQInd+2
+	sei
+	sta	IRQVec
+	stx	IRQVec+1
+	cli
 
-; Call module destructors. This is also the _exit entry.
+; Run module destructors
 
-_exit: 	pha			; Save the return code on stack
-	jsr	donelib		; Run module destructors
+NoIRQ2: jsr	donelib
 
 ; Copy back the zero page stuff
 
@@ -102,12 +129,21 @@ L2:	lda	zpsave,x
 	jmp	RESTOR
 
 
+; ------------------------------------------------------------------------
+; The IRQ vector jumps here, if condes routines are defined with type 2.
+
+IRQStub:
+	cld    	       		   	; Just to be sure
+       	jsr    	callirq                 ; Call the functions
+       	jmp    	IRQInd			; Jump to the saved IRQ vector
+
 ; ------------------------------------------------------------------------
 ; Data
 
 .data
 
 zpsave:	.res	zpspace
+IRQInd: jmp     $0000
 
 .bss
 
-- 
2.39.5