From cbdcab4fdb119e09235e246534db258f9c6135fb Mon Sep 17 00:00:00 2001
From: cuz <cuz@b7a2c559-68d2-44c3-8de9-860c34a00d81>
Date: Mon, 25 Apr 2005 20:10:10 +0000
Subject: [PATCH] Change the sematics of callirq and the existing interruptors:
 The interrupts must now return carry set if the interrupt has been handled,
 and carry clear if not. The callirq routine will stop calling handlers with
 the first handler that claims to have handled the interrupt. callirq will
 return the carry flag to the caller as it came from the last interruptor
 called.

git-svn-id: svn://svn.cc65.org/cc65/trunk@3491 b7a2c559-68d2-44c3-8de9-860c34a00d81
---
 libsrc/c128/c128-1351.s     |  7 +++++--
 libsrc/c128/c128-joymouse.s |  9 ++++++---
 libsrc/c64/c64-1351.s       |  9 ++++++---
 libsrc/c64/c64-hitjoy.s     |  8 ++++++--
 libsrc/c64/c64-joymouse.s   |  9 ++++++---
 libsrc/runtime/callirq.s    | 13 ++++++++++---
 6 files changed, 39 insertions(+), 16 deletions(-)

diff --git a/libsrc/c128/c128-1351.s b/libsrc/c128/c128-1351.s
index afb451eb8..ae8f01f04 100644
--- a/libsrc/c128/c128-1351.s
+++ b/libsrc/c128/c128-1351.s
@@ -269,7 +269,9 @@ IOCTL:  lda     #<MOUSE_ERR_INV_IOCTL     ; We don't support ioclts for now
 
 ;----------------------------------------------------------------------------
 ; IRQ: Irq handler entry point. Called as a subroutine but in IRQ context
-; (so be careful).
+; (so be careful). The routine MUST return carry set if the interrupt has been
+; 'handled' - which means that the interrupt source is gone. Otherwise it
+; MUST return carry clear.
 ;
 
 IRQ:    lda	SID_ADConv1		; Get mouse X movement
@@ -355,10 +357,11 @@ IRQ:    lda	SID_ADConv1		; Get mouse X movement
 ; Move the mouse pointer to the new X pos
 
         tya
-        jmp     CMOVEY
+        jsr     CMOVEY
 
 ; Done
 
+        clc                     ; Interrupt not "handled"
 @SkipY: rts
 
 ; --------------------------------------------------------------------------
diff --git a/libsrc/c128/c128-joymouse.s b/libsrc/c128/c128-joymouse.s
index 161d24c2d..9fad2cf6f 100644
--- a/libsrc/c128/c128-joymouse.s
+++ b/libsrc/c128/c128-joymouse.s
@@ -269,7 +269,9 @@ IOCTL:  lda     #<MOUSE_ERR_INV_IOCTL     ; We don't support ioclts for now
 
 ;----------------------------------------------------------------------------
 ; IRQ: Irq handler entry point. Called as a subroutine but in IRQ context
-; (so be careful).
+; (so be careful). The routine MUST return carry set if the interrupt has been
+; 'handled' - which means that the interrupt source is gone. Otherwise it
+; MUST return carry clear.
 ;
 
 IRQ:	lda	#$7F
@@ -381,9 +383,10 @@ IRQ:	lda	#$7F
 ; Move the mouse pointer to the new X pos
 
         tya
-        jmp     CMOVEY
+        jsr     CMOVEY
 
 ; Done
 
-@SkipY: rts
+@SkipY: clc                             ; Interrupt not "handled"
+        rts
 
diff --git a/libsrc/c64/c64-1351.s b/libsrc/c64/c64-1351.s
index 5fbc8122e..bc849acab 100644
--- a/libsrc/c64/c64-1351.s
+++ b/libsrc/c64/c64-1351.s
@@ -178,7 +178,7 @@ BOX:    ldy     #5
 ; MOVE: Move the mouse to a new position. The position is passed as it comes
 ; from the C program, that is: X on the stack and Y in a/x. The C wrapper will
 ; remove the parameter from the stack on return.
-; No checks are done if the new position is valid (within the bounding box or 
+; No checks are done if the new position is valid (within the bounding box or
 ; the screen). No return code required.
 ;
 
@@ -269,7 +269,9 @@ IOCTL:  lda     #<MOUSE_ERR_INV_IOCTL     ; We don't support ioclts for now
 
 ;----------------------------------------------------------------------------
 ; IRQ: Irq handler entry point. Called as a subroutine but in IRQ context
-; (so be careful).
+; (so be careful). The routine MUST return carry set if the interrupt has been
+; 'handled' - which means that the interrupt source is gone. Otherwise it
+; MUST return carry clear.
 ;
 
 IRQ:    lda	SID_ADConv1		; Get mouse X movement
@@ -355,10 +357,11 @@ IRQ:    lda	SID_ADConv1		; Get mouse X movement
 ; Move the mouse pointer to the new X pos
 
         tya
-        jmp     CMOVEY
+        jsr     CMOVEY                                         
 
 ; Done
 
+        clc                             ; Interrupt not handled
 @SkipY: rts
 
 ; --------------------------------------------------------------------------
diff --git a/libsrc/c64/c64-hitjoy.s b/libsrc/c64/c64-hitjoy.s
index 028d480fe..ae09182dc 100755
--- a/libsrc/c64/c64-hitjoy.s
+++ b/libsrc/c64/c64-hitjoy.s
@@ -79,8 +79,10 @@ UNINSTALL:
         rts
 
 ; ------------------------------------------------------------------------
-; IRQ entry point. Is called from the C layer as a subroutine in the 
-; interrupt.
+; IRQ entry point. Is called from the C layer as a subroutine in the
+; interrupt. The routine MUST return carry set if the interrupt has been
+; 'handled' - which means that the interrupt source is gone. Otherwise it
+; MUST return carry clear.
 
 IRQ:    ; cia 2 setup
 
@@ -156,6 +158,8 @@ fire:
         lda     #0
         sta     $dc04
 
+        ; We do never "handle" the interrupt, we use it just as a timer.
+        clc
         rts
 
 ; ------------------------------------------------------------------------
diff --git a/libsrc/c64/c64-joymouse.s b/libsrc/c64/c64-joymouse.s
index 798eaea0c..fe8bfe249 100644
--- a/libsrc/c64/c64-joymouse.s
+++ b/libsrc/c64/c64-joymouse.s
@@ -269,7 +269,9 @@ IOCTL:  lda     #<MOUSE_ERR_INV_IOCTL     ; We don't support ioclts for now
 
 ;----------------------------------------------------------------------------
 ; IRQ: Irq handler entry point. Called as a subroutine but in IRQ context
-; (so be careful).
+; (so be careful). The routine MUST return carry set if the interrupt has been
+; 'handled' - which means that the interrupt source is gone. Otherwise it
+; MUST return carry clear.
 ;
 
 IRQ:	lda	#$7F
@@ -381,9 +383,10 @@ IRQ:	lda	#$7F
 ; Move the mouse pointer to the new X pos
 
         tya
-        jmp     CMOVEY
+        jsr     CMOVEY
 
 ; Done
 
-@SkipY: rts
+@SkipY: clc                             ; Interrupt not handled
+        rts
 
diff --git a/libsrc/runtime/callirq.s b/libsrc/runtime/callirq.s
index b456ce892..15490e1ab 100644
--- a/libsrc/runtime/callirq.s
+++ b/libsrc/runtime/callirq.s
@@ -16,6 +16,11 @@
 ;      code avoids this by using locking mechanisms, but it's complex and
 ;      has a size and performance penalty.
 ;
+;   3. Special semantics: An interruptor called by callirq must tell by
+;      setting or resetting the carry flag if the interrupt has been handled
+;      (which means that the interrupt is no longer active at the interrupt
+;      source). callirq will call no other interruptors if this happens.
+;
 ; As the normal condes routine, this one has the limitation of 127 table
 ; entries.
 ;
@@ -29,7 +34,9 @@
 
 ; --------------------------------------------------------------------------
 ; Call all IRQ routines. The function needs to use self modifying code and
-; is thereforce placed in the data segment.
+; is thereforce placed in the data segment. It will return carry set if the
+; interrupt was handled and carry clear if not. The caller may choose to
+; ignore this at will.
 ; NOTE: The routine must not be called if the table is empty!
 
 .data
@@ -45,9 +52,9 @@ callirq_y:
         sta     jmpvec+1                ; Modify code below
        	sty    	index+1                 ; Modify code below
 jmpvec: jsr    	$FFFF                   ; Patched at runtime
+        bcs     done                    ; Bail out if interrupt handled
 index: 	ldy    	#$FF                    ; Patched at runtime
        	bne     callirq_y
-        rts
-
+done:   rts
 
 
-- 
2.39.5