From db4a5eed00949a6731151d6ff1d0b1a3273c7e20 Mon Sep 17 00:00:00 2001
From: pmprog <devhead@pmprog.co.uk>
Date: Wed, 24 Mar 2021 15:27:19 +0000
Subject: [PATCH 1/2] C64 VIC-II RasterIRQ methods and example

---
 examples/c64/rasterirq.mfk | 40 +++++++++++++++++++++++++++++++++
 include/c64_vic.mfk        | 46 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 85 insertions(+), 1 deletion(-)
 create mode 100644 examples/c64/rasterirq.mfk

diff --git a/examples/c64/rasterirq.mfk b/examples/c64/rasterirq.mfk
new file mode 100644
index 00000000..9abf5e79
--- /dev/null
+++ b/examples/c64/rasterirq.mfk
@@ -0,0 +1,40 @@
+
+void RasterA()
+{
+	vic_rasterirq_acknowledge()
+	vic_border = $00
+
+    vic_rasterirq_reconfigure(RasterB.addr, $40)
+	vic_raster_return()
+}
+
+void RasterB()
+{
+	vic_rasterirq_acknowledge()
+	vic_border = $04
+
+    vic_rasterirq_reconfigure(RasterC.addr, $A0)
+	vic_raster_return()
+}
+
+void RasterC()
+{
+	vic_rasterirq_acknowledge()
+	vic_border = $02
+
+    vic_rasterirq_reconfigure(RasterA.addr, $00)
+	vic_raster_return()
+}
+
+void main() 
+{
+    byte i
+
+    // Configure Raster IRQ
+    vic_rasterirq_configure(RasterA.addr, $00)
+
+	while true
+	{
+        i = 0
+	}
+}
diff --git a/include/c64_vic.mfk b/include/c64_vic.mfk
index e19d9dee..a596569e 100644
--- a/include/c64_vic.mfk
+++ b/include/c64_vic.mfk
@@ -164,4 +164,48 @@ const byte medium_gray = 12
 const byte light_green = 13
 const byte light_blue = 14
 const byte light_grey = 15
-const byte light_gray = 15
\ No newline at end of file
+const byte light_gray = 15
+
+
+asm void vic_rasterirq_configure(pointer CallbackFunction, byte RasterLine)
+{
+    sei
+    ldx CallbackFunction.lo
+    stx $0314
+    ldy CallbackFunction.hi
+    sty $0315
+    lda #$7f                    ;CIA interrupt off
+    sta $dc0d
+    lda #$01                    ;Raster interrupt on
+    sta $d01a
+    lda #27                     ;High bit of interrupt position = 0
+    sta $d011
+    lda RasterLine              ;Line where next IRQ happens
+    sta $d012
+    lda $dc0d                   ;Acknowledge IRQ (to be sure)
+    cli
+    rts
+}
+
+asm void vic_rasterirq_reconfigure(pointer CallbackFunction, byte RasterLine)
+{
+    ldx CallbackFunction.lo
+    stx $0314
+    ldy CallbackFunction.hi
+    sty $0315
+    lda RasterLine              ;Line where next IRQ happens
+    sta $d012
+    rts
+}
+
+asm macro void vic_rasterirq_acknowledge()
+{
+    lda #$FF
+    sta $D019
+}
+
+asm macro void vic_raster_return()
+{
+    lda #$00
+    jmp $EA81
+}

From b0e8b5c8d62b9aca038a3b24731df91e56913335 Mon Sep 17 00:00:00 2001
From: pmprog <devhead@pmprog.co.uk>
Date: Wed, 24 Mar 2021 15:40:50 +0000
Subject: [PATCH 2/2] Formatting update

---
 examples/c64/rasterirq.mfk | 50 ++++++++++++++++++++++----------------
 include/c64_vic.mfk        | 12 +++------
 2 files changed, 33 insertions(+), 29 deletions(-)

diff --git a/examples/c64/rasterirq.mfk b/examples/c64/rasterirq.mfk
index 9abf5e79..2d3b120a 100644
--- a/examples/c64/rasterirq.mfk
+++ b/examples/c64/rasterirq.mfk
@@ -1,40 +1,48 @@
 
-void RasterA()
-{
-	vic_rasterirq_acknowledge()
-	vic_border = $00
+void RasterA() {
+    vic_rasterirq_acknowledge()
 
+    // First raster split, set border to black
+    vic_border = black
+
+    // Set up next raster split
     vic_rasterirq_reconfigure(RasterB.addr, $40)
-	vic_raster_return()
+
+    vic_rasterirq_return()
 }
 
-void RasterB()
-{
-	vic_rasterirq_acknowledge()
-	vic_border = $04
+void RasterB() {
+    vic_rasterirq_acknowledge()
+
+    // Second raster split, Dark grey
+    vic_border = dark_grey
 
+    // Set up next raster split
     vic_rasterirq_reconfigure(RasterC.addr, $A0)
-	vic_raster_return()
+
+    vic_rasterirq_return()
 }
 
-void RasterC()
-{
-	vic_rasterirq_acknowledge()
-	vic_border = $02
+void RasterC() {
+    vic_rasterirq_acknowledge()
+
+    // Third raster split, Light grey
+    vic_border = light_grey
 
+    // Set up next raster split
     vic_rasterirq_reconfigure(RasterA.addr, $00)
-	vic_raster_return()
+
+    vic_rasterirq_return()
 }
 
-void main() 
-{
+void main() {
     byte i
 
     // Configure Raster IRQ
     vic_rasterirq_configure(RasterA.addr, $00)
 
-	while true
-	{
-        i = 0
-	}
+    // Loop forever
+    while true {
+        i = 0   // Do nothing here
+    }
 }
diff --git a/include/c64_vic.mfk b/include/c64_vic.mfk
index a596569e..1053ffb0 100644
--- a/include/c64_vic.mfk
+++ b/include/c64_vic.mfk
@@ -167,8 +167,7 @@ const byte light_grey = 15
 const byte light_gray = 15
 
 
-asm void vic_rasterirq_configure(pointer CallbackFunction, byte RasterLine)
-{
+asm void vic_rasterirq_configure(pointer CallbackFunction, byte RasterLine) {
     sei
     ldx CallbackFunction.lo
     stx $0314
@@ -187,8 +186,7 @@ asm void vic_rasterirq_configure(pointer CallbackFunction, byte RasterLine)
     rts
 }
 
-asm void vic_rasterirq_reconfigure(pointer CallbackFunction, byte RasterLine)
-{
+asm void vic_rasterirq_reconfigure(pointer CallbackFunction, byte RasterLine) {
     ldx CallbackFunction.lo
     stx $0314
     ldy CallbackFunction.hi
@@ -198,14 +196,12 @@ asm void vic_rasterirq_reconfigure(pointer CallbackFunction, byte RasterLine)
     rts
 }
 
-asm macro void vic_rasterirq_acknowledge()
-{
+asm macro void vic_rasterirq_acknowledge() {
     lda #$FF
     sta $D019
 }
 
-asm macro void vic_raster_return()
-{
+asm macro void vic_rasterirq_return() {
     lda #$00
     jmp $EA81
 }