Hello, World and build.zig

src/initramfs.asm

@@ -0,0 +1,62 @@
+; vim: ft=nasm
+org 0x7C00
+bits 16
+
+%define ENDL 0x0D, 0x0A
+
+start:
+	jmp main
+
+; 
+; echo:
+; print something to the screen
+;  - ds:si points to string
+;
+echo:
+	; save the registers we want to modify
+	push si
+	push ax
+	push bx
+
+	mov ah, 0xe
+	mov bh, 0
+
+.loop:
+	lodsb			; load byte from ds:si to al
+	or al, al		; check if next char is null
+	jz .done
+
+	int 0x10
+	jmp .loop
+
+.done:
+	pop bx
+	pop ax
+	pop si
+	ret
+
+main:
+
+	; setup data segments
+	; use ax as and intermediary as we can't write to es/ds directly
+	mov ax, 0
+	mov ds, ax
+	mov es, ax
+
+	; setup stack
+	mov ss, ax
+	mov sp, 0x7C00	; stack grows downward from where we are loaded in memory
+
+	; print the hello world
+	mov si, msg_hello
+	call echo
+
+	hlt
+
+.halt:
+	jmp .halt
+
+msg_hello: db 'Hello, world!', ENDL, 0
+
+times 510-($-$$) db 0
+dw 0AA55h

src/main.zig

@@ -1,46 +0,0 @@
-//! By convention, main.zig is where your main function lives in the case that
-//! you are building an executable. If you are making a library, the convention
-//! is to delete this file and start with root.zig instead.
-
-pub fn main() !void {
-    // Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
-    std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
-
-    // stdout is for the actual output of your application, for example if you
-    // are implementing gzip, then only the compressed bytes should be sent to
-    // stdout, not any debugging messages.
-    const stdout_file = std.io.getStdOut().writer();
-    var bw = std.io.bufferedWriter(stdout_file);
-    const stdout = bw.writer();
-
-    try stdout.print("Run `zig build test` to run the tests.\n", .{});
-
-    try bw.flush(); // Don't forget to flush!
-}
-
-test "simple test" {
-    var list = std.ArrayList(i32).init(std.testing.allocator);
-    defer list.deinit(); // Try commenting this out and see if zig detects the memory leak!
-    try list.append(42);
-    try std.testing.expectEqual(@as(i32, 42), list.pop());
-}
-
-test "use other module" {
-    try std.testing.expectEqual(@as(i32, 150), lib.add(100, 50));
-}
-
-test "fuzz example" {
-    const Context = struct {
-        fn testOne(context: @This(), input: []const u8) anyerror!void {
-            _ = context;
-            // Try passing `--fuzz` to `zig build test` and see if it manages to fail this test case!
-            try std.testing.expect(!std.mem.eql(u8, "canyoufindme", input));
-        }
-    };
-    try std.testing.fuzz(Context{}, Context.testOne, .{});
-}
-
-const std = @import("std");
-
-/// This imports the separate module containing `root.zig`. Take a look in `build.zig` for details.
-const lib = @import("zos_lib");

src/root.zig

@@ -1,13 +0,0 @@
-//! By convention, root.zig is the root source file when making a library. If
-//! you are making an executable, the convention is to delete this file and
-//! start with main.zig instead.
-const std = @import("std");
-const testing = std.testing;
-
-pub export fn add(a: i32, b: i32) i32 {
-    return a + b;
-}
-
-test "basic add functionality" {
-    try testing.expect(add(3, 7) == 10);
-}