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16dd9da1bd
Author | SHA1 | Date | |
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16dd9da1bd | |||
fa3867a6f1 | |||
497323c9f9 | |||
10e1a0466e | |||
63c3e63fe5 | |||
5be9186a2d |
5 changed files with 294 additions and 18 deletions
21
.asm-lsp.toml
Normal file
21
.asm-lsp.toml
Normal file
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@ -0,0 +1,21 @@
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[default_config]
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version = "0.10.0"
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assembler = "nasm"
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instruction_set = "x86/x86-64"
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[default_config.opts]
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compiler = "zig"
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compile_flags_txt = [
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"cc",
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"-x",
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"assembler-with-cpp",
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"-g",
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"-Wall",
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"-Wextra",
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"-pedantic",
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"-pedantic-errors",
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"-std=c2y",
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"-mllvm --x86-asm-syntax=intel",
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]
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diagnostics = true
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default_diagnostics = false
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1
.gitignore
vendored
1
.gitignore
vendored
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@ -1,2 +1,3 @@
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zig-out
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.zig-cache
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.kate-swp
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67
build.zig
67
build.zig
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@ -7,17 +7,24 @@ 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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.addAsObjFile = false,
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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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const initramfs_install = b.addInstallBinFile(initramfs.obj, "initramfs.img");
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initramfs_install.step.dependOn(&truncate(b, initramfs).step);
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var floppy = createFloppy(b, "main_floppy.img");
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floppy.run = formatFloppyFat12(b, floppy);
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b.getInstallStep().dependOn(&initramfs_install.step);
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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(b.path("zig-out/bin/initramfs.img"));
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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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@ -26,7 +33,6 @@ pub fn build(b: *std.Build) void {
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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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addAsObjFile: bool = true,
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flags: []const []const u8 = &.{},
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};
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@ -35,6 +41,46 @@ const NasmFile = struct {
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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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@ -52,12 +98,3 @@ fn addNasmFiles(b: *std.Build, options: AddNasmFilesOptions) NasmFile {
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.obj = obj,
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};
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}
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fn truncate(b: *std.Build, bin: NasmFile) *std.Build.Step.Run {
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const exec = b.addSystemCommand(&.{"truncate"});
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exec.addArgs(&.{ "-s", "1440k" });
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exec.addFileArg(bin.obj);
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exec.step.dependOn(&bin.run.step);
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return exec;
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}
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@ -2,8 +2,40 @@
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org 0x7C00
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bits 16
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%define ENDL 0x0D, 0x0A
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;
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; FAT12 Header
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;
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jmp short start
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nop
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bdb_oem: db "mkfs.fat"
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bdb_bytes_per_sector: dw 512
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bdb_sectors_per_cluster: db 1
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bdb_reserved_sectors: dw 1
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bdb_fat_count: db 2
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bdb_dir_entries_count: dw 0E0h
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bdb_total_sectors: dw 2880
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bdb_media_descriptor_type: db 0F0h
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bdb_sectors_per_fat: dw 9
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bdb_sectors_per_track: dw 18
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bdb_heads: dw 2
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bdb_hidden_sectors: dd 0
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bdb_large_sector_count: dd 0
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; Extended boot record
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ebr_drive_number: db 0
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db 0
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ebr_signature: db 29h
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ebr_volume_id: db 68h, 6Fh, 6Dh, 6Fh
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ebr_volume_laber: db 'zos disk '
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ebr_system_id: db 'FAT12 '
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start:
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jmp main
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@ -47,16 +79,139 @@ main:
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mov ss, ax
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mov sp, 0x7C00 ; stack grows downward from where we are loaded in memory
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; print the hello world
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mov si, msg_hello
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mov si, msg_startup
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call echo
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mov si, msg_reading_from_disk
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call echo
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mov [ebr_drive_number], dl
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mov ax, 1 ; second sector from disk
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mov cl, 1 ; 1 sector to read
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mov bx, 0x7E00 ; data should be after the bootloader
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call disk_read
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cli
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hlt
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; errors
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floppy_error:
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mov si, msg_read_failed
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call echo
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jmp .wait_and_reboot
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.wait_and_reboot:
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mov ah, 0
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int 16h
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jmp 0FFFFh:0 ; jump to start of bios, should reboot
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hlt
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.halt:
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cli ; disable interrupts, this way we shouldn't be able to get out of halt
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hlt
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jmp .halt
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msg_hello: db 'Hello, world!', ENDL, 0
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;
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; args:
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; ax = lba adress
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; return:
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; cx[0..5] = sector number
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; cx[6-15] = cilinder number
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; dh: head
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;
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lba_to_chs:
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push ax
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push dx
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xor dx, dx ; clear dw
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div word [bdb_sectors_per_track] ; ax = LBA / SectorsPerTrack
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; dx = LBA % SectorsPerTrack
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inc dx
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mov cx, dx ; cx = sector
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xor dx, dx ; clear dx
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div word [bdb_heads] ; ax = (LBA / SectorsPerTrack) / Heads = cylinder
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; dx = (LBA / SectorsPerTrack) % Heads = head
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mov dh, dl
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mov ch, al
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shl ah, 6
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or cl, ah ; put upper 2 bits of cylinder in CL
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pop ax
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mov dl, al
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pop ax
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ret
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;
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; args:
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; ax = LBA adress
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; cl = number of sectors to read
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; dl = drive number
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; es:bx = pointer to where to store the data
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;
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disk_read:
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push ax
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push bx
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push cx
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push dx
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push di
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push cx ; cx will be overridden
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call lba_to_chs
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pop ax ; al = number of sectors to read
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mov ah, 02h
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mov di, 3 ; hoe many times to try
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.retry:
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pusha
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stc ; set carry flag
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int 13h ; if no carry flag => it work
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jnc .done
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; read fail
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popa
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call disk_reset
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dec di
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test di, di
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jnz .retry
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.fail:
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jmp floppy_error
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.done:
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popa
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pop di
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pop dx
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pop cx
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pop bx
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pop ax
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ret
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; arg: dl = drive number
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disk_reset:
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pusha
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mov ah, 0
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stc ; set carry
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int 13h
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jc floppy_error
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popa
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ret
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msg_startup: db 'starting zos, please hold while we check for any problems', ENDL, 0
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msg_reading_from_disk: db 'testing reading from disk', ENDL, 0
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msg_read_failed: db 'error when trying to read from floppy', ENDL, 0
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times 510-($-$$) db 0
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dw 0AA55h
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62
src/kernel.asm
Normal file
62
src/kernel.asm
Normal file
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@ -0,0 +1,62 @@
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; vim: ft=nasm
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org 0x7C00
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bits 16
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%define ENDL 0x0D, 0x0A
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start:
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jmp main
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;
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; echo:
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; print something to the screen
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; - ds:si points to string
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;
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echo:
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; save the registers we want to modify
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push si
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push ax
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push bx
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mov ah, 0xe
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mov bh, 0
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.loop:
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lodsb ; load byte from ds:si to al
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or al, al ; check if next char is null
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jz .done
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int 0x10
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jmp .loop
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.done:
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pop bx
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pop ax
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pop si
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ret
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main:
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; setup data segments
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; use ax as and intermediary as we can't write to es/ds directly
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mov ax, 0
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mov ds, ax
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mov es, ax
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; setup stack
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mov ss, ax
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mov sp, 0x7C00 ; stack grows downward from where we are loaded in memory
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; print the hello world
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mov si, msg_hello
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call echo
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hlt
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.halt:
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jmp .halt
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msg_hello: db 'Hello, world!', ENDL, 0
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times 510-($-$$) db 0
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dw 0AA55h
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