refactor: Modularize IDT and PIC handling, improve structure and organization

6 files changed, 107 insertions, 74 deletions

diff --git a/mirai/common/constants/idt.zig b/mirai/common/constants/idt.zig
new file mode 100644
index 0000000..d7c7bac
--- /dev/null
+++ b/mirai/common/constants/idt.zig
@@ -0,0 +1,10 @@
+//! IDT constants
+
+pub const NUM_ENTRIES: usize = 256;
+pub const NUM_EXCEPTIONS: u8 = 32;
+
+pub const GATE_INTERRUPT: u8 = 0x8E;
+pub const GATE_TRAP: u8 = 0x8F;
+
+pub const VECTOR_TIMER: u8 = 32;
+pub const VECTOR_KEYBOARD: u8 = 33;
diff --git a/mirai/common/constants/pic.zig b/mirai/common/constants/pic.zig
new file mode 100644
index 0000000..656e9a1
--- /dev/null
+++ b/mirai/common/constants/pic.zig
@@ -0,0 +1,20 @@
+//! PIC constants
+
+pub const MASTER_CMD: u16 = 0x20;
+pub const MASTER_DATA: u16 = 0x21;
+pub const SLAVE_CMD: u16 = 0xA0;
+pub const SLAVE_DATA: u16 = 0xA1;
+
+pub const ICW1_INIT: u8 = 0x11;
+pub const ICW4_8086: u8 = 0x01;
+
+pub const MASTER_OFFSET: u8 = 0x20;
+pub const SLAVE_OFFSET: u8 = 0x28;
+
+pub const MASTER_CASCADE: u8 = 0x04;
+pub const SLAVE_CASCADE: u8 = 0x02;
+
+pub const MASK_TIMER_KEYBOARD: u8 = 0xFC;
+pub const MASK_ALL: u8 = 0xFF;
+
+pub const EOI: u8 = 0x20;
diff --git a/mirai/interrupts/handlers.zig b/mirai/interrupts/handlers.zig
new file mode 100644
index 0000000..7f8ea06
--- /dev/null
+++ b/mirai/interrupts/handlers.zig
@@ -0,0 +1,9 @@
+//! IRQ handlers
+
+const pic = @import("pic.zig");
+const sensei = @import("../kata/sensei/sensei.zig");
+
+export fn timer_handler() void {
+    pic.send_eoi_master();
+    sensei.on_tick();
+}
diff --git a/mirai/interrupts/idt.zig b/mirai/interrupts/idt.zig
index 53a425c..326f441 100644
--- a/mirai/interrupts/idt.zig
+++ b/mirai/interrupts/idt.zig
@@ -1,31 +1,19 @@
-//! Interrupt Descriptor Table - IDT setup and IRQ routing
+//! Interrupt Descriptor Table
 
 const cpu = @import("../asm/cpu.zig");
-const io = @import("../asm/io.zig");
+const gdt_const = @import("../common/constants/gdt.zig");
+const idt_const = @import("../common/constants/idt.zig");
 const isr = @import("../asm/isr.zig");
-const sensei = @import("../kata/sensei/sensei.zig");
+const pic = @import("pic.zig");
 const serial = @import("../drivers/serial/serial.zig");
+const types = @import("types.zig");
 
 comptime {
     _ = @import("../crimson/exception.zig");
+    _ = @import("handlers.zig");
 }
 
-const IDTEntry = packed struct {
-    offset_low: u16,
-    selector: u16,
-    ist: u8,
-    type_attr: u8,
-    offset_mid: u16,
-    offset_high: u32,
-    reserved: u32,
-};
-
-const IDTPointer = packed struct {
-    limit: u16,
-    base: u64,
-};
-
-var idt: [256]IDTEntry align(16) = [_]IDTEntry{.{
+var table: [idt_const.NUM_ENTRIES]types.Entry align(16) = [_]types.Entry{.{
     .offset_low = 0,
     .selector = 0,
     .ist = 0,
@@ -33,46 +21,37 @@ var idt: [256]IDTEntry align(16) = [_]IDTEntry{.{
     .offset_mid = 0,
     .offset_high = 0,
     .reserved = 0,
-}} ** 256;
+}} ** idt_const.NUM_ENTRIES;
 
-var idt_ptr: IDTPointer = undefined;
+var pointer: types.Pointer = undefined;
 
 pub fn init() void {
-    serial.print("\n=== Interrupt Descriptor Table ===\n");
+    serial.print("\n=== IDT ===\n");
 
-    // Setup exception handlers (0-31)
-    var i: u8 = 0;
-    while (i < 32) : (i += 1) {
-        const handler_addr = @intFromPtr(isr.get_exception_handler(i));
-        set_gate(i, handler_addr, 0x08, 0x8E);
+    for (0..idt_const.NUM_EXCEPTIONS) |i| {
+        const handler_addr = @intFromPtr(isr.get_exception_handler(@intCast(i)));
+        set_gate(@intCast(i), handler_addr, gdt_const.KERNEL_CODE, idt_const.GATE_INTERRUPT);
     }
 
-    // Setup IRQ handlers
-    // IRQ 0 = Timer (vector 32)
-    set_gate(32, @intFromPtr(isr.get_irq_handler(0)), 0x08, 0x8E);
-    // IRQ 1 = Keyboard (vector 33)
-    set_gate(33, @intFromPtr(isr.get_irq_handler(1)), 0x08, 0x8E);
+    set_gate(idt_const.VECTOR_TIMER, @intFromPtr(isr.get_irq_handler(0)), gdt_const.KERNEL_CODE, idt_const.GATE_INTERRUPT);
+    set_gate(idt_const.VECTOR_KEYBOARD, @intFromPtr(isr.get_irq_handler(1)), gdt_const.KERNEL_CODE, idt_const.GATE_INTERRUPT);
 
-    // Setup IDT pointer
-    idt_ptr = IDTPointer{
-        .limit = @sizeOf(@TypeOf(idt)) - 1,
-        .base = @intFromPtr(&idt),
+    pointer = types.Pointer{
+        .limit = @sizeOf(@TypeOf(table)) - 1,
+        .base = @intFromPtr(&table),
     };
 
-    // Load IDT
-    cpu.load_interrupt_descriptor_table(@intFromPtr(&idt_ptr));
+    cpu.load_interrupt_descriptor_table(@intFromPtr(&pointer));
 
-    // Remap PIC
-    remap_pic();
+    pic.remap();
 
-    // Enable interrupts
     cpu.enable_interrupts();
 
-    serial.print("IDT loaded, interrupts enabled\n");
+    serial.print("IDT loaded\n");
 }
 
 fn set_gate(num: u8, handler: u64, selector: u16, type_attr: u8) void {
-    idt[num] = IDTEntry{
+    table[num] = types.Entry{
         .offset_low = @truncate(handler & 0xFFFF),
         .selector = selector,
         .ist = 0,
@@ -82,34 +61,3 @@ fn set_gate(num: u8, handler: u64, selector: u16, type_attr: u8) void {
         .reserved = 0,
     };
 }
-
-fn remap_pic() void {
-    // ICW1: Initialize + ICW4 needed
-    io.out_byte(0x20, 0x11);
-    io.out_byte(0xA0, 0x11);
-
-    // ICW2: Vector offsets
-    io.out_byte(0x21, 0x20); // Master PIC: IRQ 0-7 -> vectors 32-39
-    io.out_byte(0xA1, 0x28); // Slave PIC: IRQ 8-15 -> vectors 40-47
-
-    // ICW3: Cascade setup
-    io.out_byte(0x21, 0x04); // Master: slave on IRQ2
-    io.out_byte(0xA1, 0x02); // Slave: cascade identity
-
-    // ICW4: 8086 mode
-    io.out_byte(0x21, 0x01);
-    io.out_byte(0xA1, 0x01);
-
-    // Mask all interrupts except IRQ0 (timer) and IRQ1 (keyboard)
-    io.out_byte(0x21, 0xFC); // 11111100 - enable IRQ0, IRQ1
-    io.out_byte(0xA1, 0xFF); // Mask all slave IRQs
-}
-
-// Timer interrupt handler
-export fn timer_handler() void {
-    // Send EOI to PIC
-    io.out_byte(0x20, 0x20);
-
-    // Update scheduler
-    sensei.on_tick();
-}
diff --git a/mirai/interrupts/pic.zig b/mirai/interrupts/pic.zig
new file mode 100644
index 0000000..df26eb3
--- /dev/null
+++ b/mirai/interrupts/pic.zig
@@ -0,0 +1,30 @@
+//! PIC remapping
+
+const io = @import("../asm/io.zig");
+const pic = @import("../common/constants/pic.zig");
+
+pub fn remap() void {
+    io.out_byte(pic.MASTER_CMD, pic.ICW1_INIT);
+    io.out_byte(pic.SLAVE_CMD, pic.ICW1_INIT);
+
+    io.out_byte(pic.MASTER_DATA, pic.MASTER_OFFSET);
+    io.out_byte(pic.SLAVE_DATA, pic.SLAVE_OFFSET);
+
+    io.out_byte(pic.MASTER_DATA, pic.MASTER_CASCADE);
+    io.out_byte(pic.SLAVE_DATA, pic.SLAVE_CASCADE);
+
+    io.out_byte(pic.MASTER_DATA, pic.ICW4_8086);
+    io.out_byte(pic.SLAVE_DATA, pic.ICW4_8086);
+
+    io.out_byte(pic.MASTER_DATA, pic.MASK_TIMER_KEYBOARD);
+    io.out_byte(pic.SLAVE_DATA, pic.MASK_ALL);
+}
+
+pub fn send_eoi_master() void {
+    io.out_byte(pic.MASTER_CMD, pic.EOI);
+}
+
+pub fn send_eoi_slave() void {
+    io.out_byte(pic.SLAVE_CMD, pic.EOI);
+    io.out_byte(pic.MASTER_CMD, pic.EOI);
+}
diff --git a/mirai/interrupts/types.zig b/mirai/interrupts/types.zig
new file mode 100644
index 0000000..ecd8513
--- /dev/null
+++ b/mirai/interrupts/types.zig
@@ -0,0 +1,16 @@
+//! IDT type definitions
+
+pub const Entry = packed struct {
+    offset_low: u16,
+    selector: u16,
+    ist: u8,
+    type_attr: u8,
+    offset_mid: u16,
+    offset_high: u32,
+    reserved: u32,
+};
+
+pub const Pointer = packed struct {
+    limit: u16,
+    base: u64,
+};