import Zig Bare Bones project

ref: https://wiki.osdev.org/Zig_Bare_Bones

6 files changed, 221 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
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index 0000000..93d6756
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/zig-cache
diff --git a/build.zig b/build.zig
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index 0000000..6aef258
--- /dev/null
+++ b/build.zig
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+const std = @import("std");
+const Builder = @import("std").build.Builder;
+const Target = @import("std").Target;
+const CrossTarget = @import("std").zig.CrossTarget;
+const Feature = @import("std").Target.Cpu.Feature;
+ 
+pub fn build(b: *Builder) void {
+    const features = Target.x86.Feature;
+ 
+    var disabled_features = Feature.Set.empty;
+    var enabled_features = Feature.Set.empty;
+ 
+    disabled_features.addFeature(@enumToInt(features.mmx));
+    disabled_features.addFeature(@enumToInt(features.sse));
+    disabled_features.addFeature(@enumToInt(features.sse2));
+    disabled_features.addFeature(@enumToInt(features.avx));
+    disabled_features.addFeature(@enumToInt(features.avx2));
+    enabled_features.addFeature(@enumToInt(features.soft_float));
+ 
+    const target = CrossTarget{
+        .cpu_arch = Target.Cpu.Arch.i386,
+        .os_tag = Target.Os.Tag.freestanding,
+        .abi = Target.Abi.none,
+        .cpu_features_sub = disabled_features,
+        .cpu_features_add = enabled_features
+    };
+ 
+    const mode = b.standardReleaseOptions();
+ 
+    const kernel = b.addExecutable("kernel.elf", "src/main.zig");
+    kernel.setTarget(target);
+    kernel.setBuildMode(mode);
+    kernel.setLinkerScriptPath(.{ .path = "src/linker.ld" });
+    kernel.code_model = .kernel;
+    kernel.install();
+ 
+    const kernel_step = b.step("kernel", "Build the kernel");
+    kernel_step.dependOn(&kernel.install_step.?.step);
+ 
+    const iso_dir = b.fmt("{s}/iso_root", .{b.cache_root});
+    const kernel_path = b.getInstallPath(kernel.install_step.?.dest_dir, kernel.out_filename);
+    const iso_path = b.fmt("{s}/disk.iso", .{b.exe_dir});
+ 
+    const iso_cmd_str = &[_][]const u8{ 
+        "/bin/sh", "-c",
+        std.mem.concat(b.allocator, u8, &[_][]const u8{
+            "mkdir -p ", iso_dir, " && ",
+            "cp ", kernel_path, " ", iso_dir, " && ",
+            "cp src/grub.cfg ", iso_dir, " && ",
+            "grub-mkrescue -o ", iso_path, " ", iso_dir
+        }) catch unreachable
+    };
+ 
+    const iso_cmd = b.addSystemCommand(iso_cmd_str);
+    iso_cmd.step.dependOn(kernel_step);
+ 
+    const iso_step = b.step("iso", "Build an ISO image");
+    iso_step.dependOn(&iso_cmd.step);
+    b.default_step.dependOn(iso_step);
+ 
+    const run_cmd_str = &[_][]const u8{
+        "qemu-system-x86_64",
+        "-cdrom", iso_path,
+        "-debugcon", "stdio",
+        "-vga", "virtio",
+        "-m", "4G",
+        "-machine", "q35,accel=kvm:whpx:tcg",
+        "-no-reboot", "-no-shutdown"
+    };
+ 
+    const run_cmd = b.addSystemCommand(run_cmd_str);
+    run_cmd.step.dependOn(b.getInstallStep());
+ 
+    const run_step = b.step("run", "Run the kernel");
+    run_step.dependOn(&run_cmd.step);
+}
diff --git a/src/console.zig b/src/console.zig
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index 0000000..6fc5043
--- /dev/null
+++ b/src/console.zig
@@ -0,0 +1,84 @@
+const fmt = @import("std").fmt;
+const Writer = @import("std").io.Writer;
+ 
+const VGA_WIDTH = 80;
+const VGA_HEIGHT = 25;
+const VGA_SIZE = VGA_WIDTH * VGA_HEIGHT;
+ 
+pub const ConsoleColors = enum(u8) {
+    Black = 0,
+    Blue = 1,
+    Green = 2,
+    Cyan = 3,
+    Red = 4,
+    Magenta = 5,
+    Brown = 6,
+    LightGray = 7,
+    DarkGray = 8,
+    LightBlue = 9,
+    LightGreen = 10,
+    LightCyan = 11,
+    LightRed = 12,
+    LightMagenta = 13,
+    LightBrown = 14,
+    White = 15,
+};
+ 
+var row: usize = 0;
+var column: usize = 0;
+var color = vgaEntryColor(ConsoleColors.LightGray, ConsoleColors.Black);
+var buffer = @as([*]volatile u16, @ptrFromInt(0xB8000));
+ 
+fn vgaEntryColor(fg: ConsoleColors, bg: ConsoleColors) u8 {
+    return @enumToInt(fg) | (@enumToInt(bg) << 4);
+}
+ 
+fn vgaEntry(uc: u8, new_color: u8) u16 {
+    var c: u16 = new_color;
+ 
+    return uc | (c << 8);
+}
+ 
+pub fn initialize() void {
+    clear();
+}
+ 
+pub fn setColor(new_color: u8) void {
+    color = new_color;
+}
+ 
+pub fn clear() void {
+    @memset(u16, buffer[0..VGA_SIZE], vgaEntry(' ', color));
+}
+ 
+pub fn putCharAt(c: u8, new_color: u8, x: usize, y: usize) void {
+    const index = y * VGA_WIDTH + x;
+    buffer[index] = vgaEntry(c, new_color);
+}
+ 
+pub fn putChar(c: u8) void {
+    putCharAt(c, color, column, row);
+    column += 1;
+    if (column == VGA_WIDTH) {
+        column = 0;
+        row += 1;
+        if (row == VGA_HEIGHT)
+            row = 0;
+    }
+}
+ 
+pub fn puts(data: []const u8) void {
+    for (data) |c|
+        putChar(c);
+}
+ 
+pub const writer = Writer(void, error{}, callback){ .context = {} };
+ 
+fn callback(_: void, string: []const u8) error{}!usize {
+    puts(string);
+    return string.len;
+}
+ 
+pub fn printf(comptime format: []const u8, args: anytype) void {
+    fmt.format(writer, format, args) catch unreachable;
+}
diff --git a/src/grub.cfg b/src/grub.cfg
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index 0000000..7904bf7
--- /dev/null
+++ b/src/grub.cfg
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+menuentry "Zig Bare Bones" {
+	multiboot /boot/kernel.elf
+}
diff --git a/src/linker.ld b/src/linker.ld
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index 0000000..429da33
--- /dev/null
+++ b/src/linker.ld
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+ENTRY(_start)
+ 
+SECTIONS {
+    . = 1M;
+ 
+    .multiboot {
+        KEEP(*(.multiboot))
+    }
+ 
+    .text : ALIGN(4K) {
+        *(.text)
+    }
+ 
+    .rodata : ALIGN(4K) {
+        *(.rodata)
+    }
+ 
+    .data : ALIGN(4K) {
+        *(.data)
+    }
+ 
+    .bss : ALIGN(4K) {
+        *(COMMON)
+        *(.bss)
+    }
+}
diff --git a/src/main.zig b/src/main.zig
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index 0000000..298e2c2
--- /dev/null
+++ b/src/main.zig
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+const console = @import("console.zig");
+ 
+const ALIGN = 1 << 0;
+const MEMINFO = 1 << 1;
+const MAGIC = 0x1BADB002;
+const FLAGS = ALIGN | MEMINFO;
+ 
+const MultibootHeader = packed struct {
+    magic: i32 = MAGIC,
+    flags: i32,
+    checksum: i32,
+};
+ 
+export var multiboot align(4) linksection(".multiboot") = MultibootHeader{
+    .flags = FLAGS,
+    .checksum = -(MAGIC + FLAGS),
+};
+ 
+export var stack_bytes: [16 * 1024]u8 align(16) linksection(".bss") = undefined;
+const stack_bytes_slice = stack_bytes[0..];
+ 
+export fn _start() callconv(.Naked) noreturn {
+    @call(.{ .stack = stack_bytes_slice }, kmain, .{});
+ 
+    while (true) {}
+}
+ 
+fn kmain() void {
+    console.initialize();
+    console.puts("Hello world!");
+}