rework

build.zig

@@ -7,14 +7,21 @@ pub fn build(b: *std.Build) void {
     const initramfs = addNasmFiles(b, AddNasmFilesOptions{
         .filename = "src/initramfs.asm",
         .outputname = "initramfs.bin",
-        .addAsObjFile = false,
+        .flags = &.{"-f bin"},
+    });
+    const kernel = addNasmFiles(b, AddNasmFilesOptions{
+        .filename = "src/kernel.asm",
+        .outputname = "kernel.bin",
         .flags = &.{"-f bin"},
     });
 
-    const initramfs_install = b.addInstallBinFile(initramfs.obj, "initramfs.img");
+    var floppy = createFloppy(b, "main_floppy.img");
-    initramfs_install.step.dependOn(&truncate(b, initramfs).step);
+    floppy.run = formatFloppyFat12(b, floppy);
 
-    b.getInstallStep().dependOn(&initramfs_install.step);
+    const img_install = b.addInstallBinFile(floppy.obj, "main_floppy.img");
+    img_install.step.dependOn(&installImgToFloppy(b, floppy, initramfs, kernel).step);
+
+    b.getInstallStep().dependOn(&img_install.step);
 
     const run = b.addSystemCommand(&.{ "qemu-system-i386", "-fda" });
     run.addFileArg(b.path("zig-out/bin/initramfs.img"));
@@ -26,7 +33,6 @@ pub fn build(b: *std.Build) void {
 const AddNasmFilesOptions = struct {
     filename: []const u8,
     outputname: ?[]const u8 = null,
-    addAsObjFile: bool = true,
     flags: []const []const u8 = &.{},
 };
 
@@ -35,6 +41,46 @@ const NasmFile = struct {
     obj: std.Build.LazyPath,
 };
 
+const Floppydisk = NasmFile;
+
+fn createFloppy(b: *std.Build, name: []const u8) Floppydisk {
+    const dd = b.addSystemCommand(&.{ "dd", "if=/dev/zero" });
+    const Floppy = dd.addPrefixedOutputFileArg("of=", name);
+    dd.addArgs(&.{ "bs=512", "count=2880" });
+
+    return Floppydisk{
+        .run = dd,
+        .obj = Floppy,
+    };
+}
+
+fn formatFloppyFat12(b: *std.Build, floppy: Floppydisk) *std.Build.Step.Run {
+    const mkfs = b.addSystemCommand(&.{ "mkfs.fat", "-F12", "-nNBOS" });
+    mkfs.addFileArg(floppy.obj);
+
+    mkfs.step.dependOn(&floppy.run.step);
+
+    return mkfs;
+}
+
+fn installImgToFloppy(b: *std.Build, floppy: Floppydisk, bootloader: NasmFile, kernel: NasmFile) *std.Build.Step.Run {
+    const dd = b.addSystemCommand(&.{"dd"});
+    dd.addPrefixedFileArg("if=", bootloader.obj);
+    dd.addPrefixedFileArg("of=", floppy.obj);
+    dd.addArg("conv=notrunc");
+    dd.step.dependOn(&floppy.run.step);
+    dd.step.dependOn(&bootloader.run.step);
+
+    const mcopy = b.addSystemCommand(&.{"mcopy"});
+    mcopy.addPrefixedFileArg("-i", floppy.obj);
+    mcopy.addFileArg(kernel.obj);
+    mcopy.addArg("::kernel.bin");
+    mcopy.step.dependOn(&dd.step);
+    mcopy.step.dependOn(&kernel.run.step);
+
+    return mcopy;
+}
+
 // adapted from https://codeberg.org/raddari/zig-nasm-lib.git
 fn addNasmFiles(b: *std.Build, options: AddNasmFilesOptions) NasmFile {
     std.debug.assert(!std.fs.path.isAbsolute(options.filename));
@@ -52,12 +98,3 @@ fn addNasmFiles(b: *std.Build, options: AddNasmFilesOptions) NasmFile {
         .obj = obj,
     };
 }
-
-fn truncate(b: *std.Build, bin: NasmFile) *std.Build.Step.Run {
-    const exec = b.addSystemCommand(&.{"truncate"});
-    exec.addArgs(&.{ "-s", "1440k" });
-    exec.addFileArg(bin.obj);
-    exec.step.dependOn(&bin.run.step);
-
-    return exec;
-}