feat: Implement Mirai kernel with boot parameter handling and framebuffer support

2 files changed, 225 insertions, 0 deletions

diff --git a/mirai/kernel/boot.zig b/mirai/kernel/boot.zig
new file mode 100644
index 0000000..8d46901
--- /dev/null
+++ b/mirai/kernel/boot.zig
@@ -0,0 +1,92 @@
+//! Mirai Boot Parameters
+//!
+//! This structure matches what Hikari bootloader passes to the kernel.
+
+pub const boot_params_magic: u64 = 0x494152494D424B41; // "AKBMIRAI"
+pub const boot_params_version: u32 = 1;
+
+pub const BootParams = extern struct {
+    magic: u64,
+    version: u32,
+    size: u32,
+
+    framebuffer: FramebufferInfo,
+    memory_map: MemoryMapInfo,
+    kernel: KernelInfo,
+    acpi: AcpiInfo,
+    boot_time: u64,
+
+    reserved: [256]u8,
+
+    pub fn is_valid(self: *const BootParams) bool {
+        return self.magic == boot_params_magic and
+            self.version == boot_params_version;
+    }
+};
+
+pub const FramebufferInfo = extern struct {
+    base: u64,
+    size: u64,
+    width: u32,
+    height: u32,
+    stride: u32,
+    pixel_format: PixelFormat,
+    red_mask_size: u8,
+    red_mask_shift: u8,
+    green_mask_size: u8,
+    green_mask_shift: u8,
+    blue_mask_size: u8,
+    blue_mask_shift: u8,
+    reserved: [2]u8,
+};
+
+pub const PixelFormat = enum(u32) {
+    rgb = 0,
+    bgr = 1,
+    bitmask = 2,
+    unknown = 255,
+};
+
+pub const MemoryMapInfo = extern struct {
+    entries: u64,
+    entry_count: u32,
+    entry_size: u32,
+    descriptor_version: u32,
+    reserved: u32,
+};
+
+pub const MemoryRegion = extern struct {
+    base: u64,
+    size: u64,
+    region_type: MemoryType,
+    attributes: u64,
+};
+
+pub const MemoryType = enum(u32) {
+    usable = 0,
+    reserved = 1,
+    acpi_reclaimable = 2,
+    acpi_nvs = 3,
+    bad_memory = 4,
+    bootloader_reclaimable = 5,
+    kernel = 6,
+    framebuffer = 7,
+};
+
+pub const KernelInfo = extern struct {
+    physical_base: u64,
+    virtual_base: u64,
+    size: u64,
+    entry_point: u64,
+    pml4_address: u64,
+    physmap_base: u64,
+    physmap_size: u64,
+    stack_top: u64,
+    stack_size: u64,
+};
+
+pub const AcpiInfo = extern struct {
+    rsdp_address: u64,
+    rsdp_version: u32,
+    reserved: u32,
+};
diff --git a/mirai/kernel/mirai.zig b/mirai/kernel/mirai.zig
new file mode 100644
index 0000000..5d2bc66
--- /dev/null
+++ b/mirai/kernel/mirai.zig
@@ -0,0 +1,133 @@
+//! Mirai - AkibaOS Kernel
+//!
+//! The kernel receives boot parameters from Hikari bootloader
+//! and initializes the system.
+
+const boot = @import("boot.zig");
+
+pub export fn mirai(boot_params_ptr: *boot.BootParams) callconv(.{ .x86_64_sysv = .{} }) noreturn {
+    // Validate boot parameters
+    if (!boot_params_ptr.is_valid()) {
+        // Invalid boot params - halt with error pattern
+        if (boot_params_ptr.framebuffer.base != 0) {
+            draw_error_screen(boot_params_ptr);
+        }
+        halt();
+    }
+
+    // Draw success screen
+    draw_boot_screen(boot_params_ptr);
+
+    // Halt for now
+    halt();
+}
+
+fn draw_boot_screen(params: *boot.BootParams) void {
+    const fb = params.framebuffer;
+    const base: [*]u32 = @ptrFromInt(fb.base);
+    const stride = fb.stride;
+
+    // Clear screen to dark purple (Akiba theme)
+    const bg_color: u32 = switch (fb.pixel_format) {
+        .rgb => 0x1E0030, // RGB
+        .bgr => 0x30001E, // BGR
+        else => 0x1E0030,
+    };
+
+    var y: u32 = 0;
+    while (y < fb.height) : (y += 1) {
+        var x: u32 = 0;
+        while (x < fb.width) : (x += 1) {
+            base[y * stride + x] = bg_color;
+        }
+    }
+
+    // Draw "MIRAI" banner in cyan
+    const text_color: u32 = switch (fb.pixel_format) {
+        .rgb => 0x00FFFF, // RGB cyan
+        .bgr => 0xFFFF00, // BGR cyan
+        else => 0x00FFFF,
+    };
+
+    const banner = [_][]const u8{
+        "  M   M  III  RRRR    A    III ",
+        "  MM MM   I   R   R  A A    I  ",
+        "  M M M   I   RRRR  AAAAA   I  ",
+        "  M   M   I   R R   A   A   I  ",
+        "  M   M  III  R  R  A   A  III ",
+    };
+
+    const start_x = (fb.width - 31 * 8) / 2;
+    const start_y = fb.height / 3;
+
+    for (banner, 0..) |line, row| {
+        for (line, 0..) |char, col| {
+            if (char != ' ') {
+                draw_block(base, stride, start_x + @as(u32, @truncate(col)) * 8, start_y + @as(u32, @truncate(row)) * 12, text_color);
+            }
+        }
+    }
+
+    // Draw "AkibaOS" subtitle
+    const subtitle = "AkibaOS Kernel Loaded Successfully";
+    const subtitle_x = (fb.width - @as(u32, @truncate(subtitle.len)) * 8) / 2;
+    const subtitle_y = start_y + 80;
+
+    for (0..subtitle.len) |i| {
+        draw_small_block(base, stride, subtitle_x + @as(u32, @truncate(i)) * 8, subtitle_y, 0xFF80C0);
+    }
+}
+
+fn draw_error_screen(params: *boot.BootParams) void {
+    const fb = params.framebuffer;
+    const base: [*]u32 = @ptrFromInt(fb.base);
+    const stride = fb.stride;
+
+    // Fill with red
+    const error_color: u32 = switch (fb.pixel_format) {
+        .rgb => 0xFF0000,
+        .bgr => 0x0000FF,
+        else => 0xFF0000,
+    };
+
+    var y: u32 = 0;
+    while (y < fb.height) : (y += 1) {
+        var x: u32 = 0;
+        while (x < fb.width) : (x += 1) {
+            base[y * stride + x] = error_color;
+        }
+    }
+}
+
+fn draw_block(base: [*]u32, stride: u32, x: u32, y: u32, color: u32) void {
+    var dy: u32 = 0;
+    while (dy < 10) : (dy += 1) {
+        var dx: u32 = 0;
+        while (dx < 6) : (dx += 1) {
+            base[(y + dy) * stride + x + dx] = color;
+        }
+    }
+}
+
+fn draw_small_block(base: [*]u32, stride: u32, x: u32, y: u32, color: u32) void {
+    var dy: u32 = 0;
+    while (dy < 2) : (dy += 1) {
+        var dx: u32 = 0;
+        while (dx < 6) : (dx += 1) {
+            base[(y + dy) * stride + x + dx] = color;
+        }
+    }
+}
+
+fn halt() noreturn {
+    while (true) {
+        asm volatile ("hlt");
+    }
+}
+
+pub fn panic(msg: []const u8, stack_trace: ?*@import("std").builtin.StackTrace, ret_addr: ?usize) noreturn {
+    _ = msg;
+    _ = stack_trace;
+    _ = ret_addr;
+    halt();
+}