100 lines
3.1 KiB
Zig
100 lines
3.1 KiB
Zig
const std = @import("std");
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// Although this function looks imperative, note that its job is to
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// declaratively construct a build graph that will be executed by an external
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// runner.
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pub fn build(b: *std.Build) void {
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const initramfs = addNasmFiles(b, AddNasmFilesOptions{
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.filename = "src/initramfs.asm",
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.outputname = "initramfs.bin",
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.flags = &.{"-f bin"},
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});
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const kernel = addNasmFiles(b, AddNasmFilesOptions{
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.filename = "src/kernel.asm",
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.outputname = "kernel.bin",
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.flags = &.{"-f bin"},
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});
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var floppy = createFloppy(b, "main_floppy.img");
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floppy.run = formatFloppyFat12(b, floppy);
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const img_install = b.addInstallBinFile(floppy.obj, "main_floppy.img");
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img_install.step.dependOn(&installImgToFloppy(b, floppy, initramfs, kernel).step);
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b.getInstallStep().dependOn(&img_install.step);
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const run = b.addSystemCommand(&.{ "qemu-system-i386", "-fda" });
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run.addFileArg(floppy.obj);
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const run_step = b.step("run", "run the os in qemu");
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run_step.dependOn(&run.step);
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}
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const AddNasmFilesOptions = struct {
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filename: []const u8,
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outputname: ?[]const u8 = null,
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flags: []const []const u8 = &.{},
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};
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const NasmFile = struct {
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run: *std.Build.Step.Run,
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obj: std.Build.LazyPath,
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};
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const Floppydisk = NasmFile;
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fn createFloppy(b: *std.Build, name: []const u8) Floppydisk {
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const dd = b.addSystemCommand(&.{ "dd", "if=/dev/zero" });
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const Floppy = dd.addPrefixedOutputFileArg("of=", name);
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dd.addArgs(&.{ "bs=512", "count=2880" });
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return Floppydisk{
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.run = dd,
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.obj = Floppy,
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};
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}
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fn formatFloppyFat12(b: *std.Build, floppy: Floppydisk) *std.Build.Step.Run {
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const mkfs = b.addSystemCommand(&.{ "mkfs.fat", "-F12", "-nNBOS" });
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mkfs.addFileArg(floppy.obj);
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mkfs.step.dependOn(&floppy.run.step);
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return mkfs;
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}
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fn installImgToFloppy(b: *std.Build, floppy: Floppydisk, bootloader: NasmFile, kernel: NasmFile) *std.Build.Step.Run {
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const dd = b.addSystemCommand(&.{"dd"});
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dd.addPrefixedFileArg("if=", bootloader.obj);
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dd.addPrefixedFileArg("of=", floppy.obj);
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dd.addArg("conv=notrunc");
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dd.step.dependOn(&floppy.run.step);
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dd.step.dependOn(&bootloader.run.step);
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const mcopy = b.addSystemCommand(&.{"mcopy"});
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mcopy.addPrefixedFileArg("-i", floppy.obj);
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mcopy.addFileArg(kernel.obj);
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mcopy.addArg("::kernel.bin");
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mcopy.step.dependOn(&dd.step);
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mcopy.step.dependOn(&kernel.run.step);
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return mcopy;
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}
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// adapted from https://codeberg.org/raddari/zig-nasm-lib.git
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fn addNasmFiles(b: *std.Build, options: AddNasmFilesOptions) NasmFile {
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std.debug.assert(!std.fs.path.isAbsolute(options.filename));
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const src_file = b.path(options.filename);
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const output = options.outputname orelse b.fmt("{s}.o", .{std.mem.sliceTo(options.filename, '.')});
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const nasm = b.addSystemCommand(&.{"nasm"});
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nasm.addArgs(options.flags);
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nasm.addPrefixedDirectoryArg("-i", b.path("src"));
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const obj = nasm.addPrefixedOutputFileArg("-o", output);
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nasm.addFileArg(src_file);
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return .{
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.run = nasm,
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.obj = obj,
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};
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}
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