add interrupt init code (and increase rtc tick rate)

sw/kernel/devices/interrupt.s

@@ -1,51 +0,0 @@
-; ---------------------------------------------------------------------------
-; interrupt.s
-; ---------------------------------------------------------------------------
-;
-; Interrupt handler.
-;
-; Checks for a BRK instruction and returns from all valid interrupts.
-
-.import   _handle_irq
-.import _cputc, _clrscr
-
-.export   _irq_int, _nmi_int
-
-.include "io.inc65"
-
-.segment  "CODE"
-
-.PC02                             ; Force 65C02 assembly mode
-
-; ---------------------------------------------------------------------------
-; Non-maskable interrupt (NMI) service routine
-
-_nmi_int:  RTI                    ; Return from all NMI interrupts
-
-; ---------------------------------------------------------------------------
-; Maskable interrupt (IRQ) service routine
-
-_irq_int:  PHX                    ; Save X register contents to stack
-           TSX                    ; Transfer stack pointer to X
-           PHA                    ; Save accumulator contents to stack
-           INX                    ; Increment X so it points to the status
-           INX                    ;   register value saved on the stack
-           LDA $100,X             ; Load status register contents
-           AND #$10               ; Isolate B status bit
-           BNE break              ; If B = 1, BRK detected
-
-; ---------------------------------------------------------------------------
-; IRQ detected, return
-
-irq:       PLA                    ; Restore accumulator contents
-           PLX                    ; Restore X register contents
-           jsr _handle_irq        ; Handle the IRQ
-           RTI                    ; Return from all IRQ interrupts
-
-; ---------------------------------------------------------------------------
-; BRK detected, stop
-
-break:
-        pla
-        plx
-        rti

sw/kernel/devices/rtc.s

@@ -14,6 +14,18 @@ RTC_IRQ_THRESHOLD   = $20
 RTC_OUTPUT          = $30
 RTC_CONTROL         = $30
 
+THRESHOLD_0         = $a0
+; THRESHOLD_1         = $0f
+THRESHOLD_1         = $00
+THRESHOLD_2         = $00
+THRESHOLD_3         = $00
+
+; IRQ_THRESHOLD_0     = $32
+IRQ_THRESHOLD_0     = $10
+IRQ_THRESHOLD_1     = $00
+IRQ_THRESHOLD_2     = $00
+IRQ_THRESHOLD_3     = $00
+
 ; void init_rtc(void);
 ; Initialize rtc and generate 50ms interrupts
 .proc _init_rtc
@@ -36,36 +48,36 @@ RTC_CONTROL         = $30
 
     lda #RTC_THRESHOLD+0    ; Set threshold to 4000 ($fa0)
     sta RTC_CMD
-    lda #$a0
+    lda #THRESHOLD_0
     sta RTC_DAT
     lda #RTC_THRESHOLD+1
     sta RTC_CMD
-    lda #$0f
+    lda #THRESHOLD_1
     sta RTC_DAT
     lda #RTC_THRESHOLD+2
     sta RTC_CMD
-    lda #$00
+    lda #THRESHOLD_2
     sta RTC_DAT
     lda #RTC_THRESHOLD+3
     sta RTC_CMD
-    lda #$00
+    lda #THRESHOLD_3
     sta RTC_DAT
 
     lda #RTC_IRQ_THRESHOLD+0    ; Set irq threshold to 50 ($32)
     sta RTC_CMD
-    lda #$32
+    lda #IRQ_THRESHOLD_0
     sta RTC_DAT
     lda #RTC_IRQ_THRESHOLD+1
     sta RTC_CMD
-    lda #$00
+    lda #IRQ_THRESHOLD_1
     sta RTC_DAT
     lda #RTC_IRQ_THRESHOLD+2
     sta RTC_CMD
-    lda #$00
+    lda #IRQ_THRESHOLD_2
     sta RTC_DAT
     lda #RTC_IRQ_THRESHOLD+3
     sta RTC_CMD
-    lda #$00
+    lda #IRQ_THRESHOLD_3
     sta RTC_DAT
 
     lda #$30

sw/kernel/interrupts/interrupt.h

@@ -9,6 +9,8 @@
 void irq_int();
 void nmi_int();
 
+void register_irq(void* addr, uint8_t irqn);
+
 uint8_t irq_get_status();
 void irq_set_status(uint8_t);
 

sw/kernel/interrupts/interrupt.s

@@ -0,0 +1,43 @@
+.MACPACK generic
+
+.autoimport
+
+.export   _irq_int, _nmi_int
+.export _register_irq
+
+IRQ_CMD_ADDR    = $effc
+IRQ_DAT_ADDR    = $effd
+
+IRQ_CMD_READIRQ = $00
+
+.proc _nmi_int
+rti
+.endproc
+
+
+; _irq_int
+.proc _irq_int
+    ; Load IRQ number
+    lda #IRQ_CMD_READIRQ
+    sta IRQ_CMD_ADDR
+    lda IRQ_DAT_ADDR
+    ; shift by 2 (oh so only 128 interrupts are supported lol)
+    lsr
+    tax
+    jmp (irq_table,x)
+    ; use that to index jump table
+.endproc
+
+; void register_irq(void* addr, uint8_t irqn);
+.proc _register_irq
+    tax
+    jsr popa
+    sta irq_table,x
+    jsr popa
+    sta irq_table+1,x
+    rts
+.endproc
+
+.data
+; interrupt handler jump table
+irq_table: .res 256

sw/kernel/irq.c

@@ -2,7 +2,7 @@
 #include <stdint.h>
 #include <conio.h>
 
-#include "devices/interrupt.h"
+#include "interrupts/interrupt.h"
 #include "devices/uart.h"
 
 

sw/kernel/kernel.c

@@ -1,8 +1,14 @@
 #include <conio.h>
 #include "devices/interrupt_controller.h"
+#include "interrupts/interrupt.h"
 #include "devices/rtc.h"
 
 
+void handle_rtc_interrupt() {
+    cputs("In IRQ interrupt!\n");
+    asm volatile ("rti");
+}
+
 int main() {
 
     cputs("Kernel\n");
@@ -19,6 +25,8 @@ int main() {
     cputs("Initialize RTC\n");
     init_rtc();
 
+    register_irq(&handle_rtc_interrupt, 0);
+
     // cputs("Initialize Serial\n");
     // // init_serial();
     // enable_irq(2, IRQ_EDGE);
@@ -26,4 +34,4 @@ int main() {
     while(1);
 
     return 0;
-}
+}