Init rtc and pic in kernel

sw/kernel/devices/interrupt_controller.s

@@ -0,0 +1,136 @@
+.MACPACK generic
+
+.autoimport
+
+.importzp tmp1, tmp2
+
+.export _init_interrupt_controller
+.export _enable_irq
+.export _disable_irq
+.export _send_eoi
+
+IRQ_CMD_ADDR    = $effc
+IRQ_DAT_ADDR    = $effd
+
+IRQ_CMD_MASK    = $e0
+IRQ_REG_MASK    = $1f
+IRQ_CMD_READIRQ = $00
+IRQ_CMD_ENABLE  = $20
+IRQ_CMD_TYPE    = $40
+IRQ_CMD_EOI     = $ff
+
+.code
+
+; void init_irq();
+; mask all IRQs, set all type to edge.
+.proc _init_interrupt_controller
+    ldx #$20    ; enable
+    ldy #$ff
+    jsr cmd_all
+    ldx #$40    ; edge type
+    ldy #$00
+    jsr cmd_all
+    rts
+
+cmd_all:        ; Send the same value to all 32 bytes
+    txa
+    add #$20
+    sta tmp1
+loop:
+    txa
+    sta IRQ_CMD_ADDR
+    tya
+    sta IRQ_DAT_ADDR
+    inx
+    cpx tmp1
+    blt loop
+    rts
+.endproc
+
+
+; void enable_irq(uint8_t type, uint8_t irqnum);
+; in A: 
+.proc _enable_irq
+    ; Decide which byte we need to modify by dividing by 32 (>> 5)
+    pha
+    lsr
+    lsr
+    lsr
+    lsr
+    lsr         ; A is now bytesel
+    sta tmp2    ; tmp2 is now bytesel
+    add #IRQ_CMD_ENABLE
+    sta IRQ_CMD_ADDR
+    lda IRQ_DAT_ADDR
+    sta tmp1
+    pla
+    and $07     ; A is now 0-7
+    tax
+    inx         ; X is now 1-8
+    lda #$01
+L1: dex
+    beq L2
+    asl
+    bra L1  
+L2: pha         ; Push bit mask to stack
+    ora tmp1    ; A is now 1 << (0-7) | enable
+    sta IRQ_DAT_ADDR
+
+
+    lda tmp2
+    add #IRQ_CMD_TYPE
+    sta IRQ_CMD_ADDR
+    lda IRQ_DAT_ADDR
+    sta tmp1
+    jsr popa    ; A is now type
+    beq bit0
+bit1:           ; set `bit` to 1
+    pla
+    ora tmp1
+    bra L3
+bit0:           ; set `bit` to 0
+    pla
+    eor #$ff
+    and tmp1
+L3: sta IRQ_DAT_ADDR
+    rts
+
+.endproc
+
+.proc _disable_irq
+    ; Decide which byte we need to modify by dividing by 32 (>> 5)
+    pha
+    lsr
+    lsr
+    lsr
+    lsr
+    lsr         ; A is now bytesel
+    add #IRQ_CMD_ENABLE
+    sta IRQ_CMD_ADDR
+    lda IRQ_DAT_ADDR
+    sta tmp1
+    pla
+    and $07     ; A is now 0-7
+    tax
+    inx         ; X is now 1-8
+    lda #$01
+L1: dex
+    beq L2
+    asl
+    bra L1  
+L2: eor #$ff    ; Invert to set enable to 0
+    and tmp1    ; a is now ~(1 << (0-7)) & enable
+    sta IRQ_DAT_ADDR
+    rts
+.endproc
+
+; This should accept irqnum later.
+; void send_eoi();
+.proc _send_eoi
+    lda #IRQ_CMD_EOI
+    sta IRQ_CMD_ADDR
+    lda #$1
+    sta IRQ_DAT_ADDR
+    rts
+.endproc
+