Add init code for mapper

init_mapper now remaps so that it can change irq vectors

hw/efinix_fpga/.gitignore

@@ -7,4 +7,4 @@ outflow
 *.gtkw
 *.vvp
 
-.mem
+*.mem

sw/kernel/devices/mapper.h

@@ -0,0 +1,10 @@
+#ifndef _MAPPER_H
+#define _MAPPER_H
+
+#include <stdint.h>
+
+void init_mapper();
+
+void map(uint16_t p_page, uint8_t v_page); 
+
+#endif

sw/kernel/devices/mapper.s

@@ -0,0 +1,38 @@
+.MACPACK generic
+
+.autoimport
+
+.export _init_mapper
+.export _map
+
+MAPPER_BASE = $200
+
+.code
+
+; void init_paging();
+; This should be identity mapped at reset, but we can do it again anyway
+.proc _init_mapper
+    ldx #$00
+L1:
+    txa
+    lsr
+    sta MAPPER_BASE,x
+    lda #$00
+    sta MAPPER_BASE+1,x
+    inx
+    inx
+    cpx #$20
+    blt L1
+    rts 
+.endproc
+
+; void map(uint16_t p_page, uint8_t v_page); 
+.proc _map
+    asl
+    tax                 ; x = v_page * 2
+    jsr popa            ; low byte of p_page
+    sta MAPPER_BASE,x   ; write low byte to mm_low
+    jsr popa            ; high byte of p_page
+    sta MAPPER_BASE+1,x ; write high byte to mm_high
+    rts
+.endproc

sw/kernel/interrupts/interrupt.h

@@ -6,6 +6,8 @@
 #define BUTTON  (1 << 0)
 #define UART    (1 << 1)
 
+void init_interrupts();
+
 void register_irq(void* addr, uint8_t irqn);
 
 uint8_t irq_get_status();

sw/kernel/interrupts/interrupt.s

@@ -3,15 +3,38 @@
 .autoimport
 
 .import _enable_irq
+.import _map
 
 .export   irq_int, nmi_int
 .export _register_irq
+.export _init_interrupts
 
 IRQ_CMD_ADDR    = $effc
 IRQ_DAT_ADDR    = $effd
 
 IRQ_CMD_READIRQ = $00
 
+; void init_interrupts();
+; remap the upper page into ram,
+; then load the new vector addresses.
+.proc _init_interrupts
+    ; map(001f, f);
+    lda #$1f
+    jsr pushax
+    lda #$f
+    jsr _map
+
+    lda #<irq_int
+    sta $fffe
+    lda #>irq_int
+    sta $ffff
+    
+    lda #<nmi_int
+    sta $fffa
+    lda #>nmi_int
+    sta $fffb
+    rts
+.endproc
 
 .proc nmi_int
 rti

sw/kernel/kernel.c

@@ -1,6 +1,7 @@
 #include <conio.h>
 #include "devices/interrupt_controller.h"
 #include "interrupts/interrupt.h"
+#include "devices/mapper.h"
 #include "devices/rtc.h"
 
 
@@ -13,11 +14,11 @@ int main() {
 
     cputs("Kernel\n");
 
-    // cputs("Init Paging\n")
-    // init_paging()
+    cputs("Init Mapper\n");
+    init_mapper();
 
-    // cputs("Initialize Interrupts\n");
-    // init_interrupts();
+    cputs("Initialize Interrupts\n");
+    init_interrupts();
 
     cputs("Initialize Interrupt Controller\n");
     init_interrupt_controller();