commit 5047cb829dd4d38eab3c4c454d73772af562f594
Author: Sylvia Ivory <git@sivory.net>
Date: Sat, 10 Jan 2026 13:44:01 -0800
Initial Commit
Diffstat:
7 files changed, 197 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1,2 @@
+/.zig-cache
+/zig-out
diff --git a/build.zig b/build.zig
@@ -0,0 +1,24 @@
+const std = @import("std");
+const fs = std.fs;
+
+const target: std.Target.Query = .{
+ .cpu_arch = .arm,
+ .os_tag = .freestanding,
+};
+
+pub fn build(b: *std.Build) !void {
+ const exe = b.addExecutable(.{
+ .name = "SylveOS",
+ .root_module = b.createModule(.{
+ .root_source_file = b.path("src/root.zig"),
+ .target = b.resolveTargetQuery(target),
+ .optimize = .ReleaseSafe,
+ .unwind_tables = .none,
+ .single_threaded = true,
+ }),
+ .linkage = .static,
+ });
+
+ exe.setLinkerScript(b.path("linker.ld"));
+ b.installArtifact(exe);
+}
diff --git a/build.zig.zon b/build.zig.zon
@@ -0,0 +1,81 @@
+.{
+ // This is the default name used by packages depending on this one. For
+ // example, when a user runs `zig fetch --save <url>`, this field is used
+ // as the key in the `dependencies` table. Although the user can choose a
+ // different name, most users will stick with this provided value.
+ //
+ // It is redundant to include "zig" in this name because it is already
+ // within the Zig package namespace.
+ .name = .SylveOS,
+ // This is a [Semantic Version](https://semver.org/).
+ // In a future version of Zig it will be used for package deduplication.
+ .version = "0.0.0",
+ // Together with name, this represents a globally unique package
+ // identifier. This field is generated by the Zig toolchain when the
+ // package is first created, and then *never changes*. This allows
+ // unambiguous detection of one package being an updated version of
+ // another.
+ //
+ // When forking a Zig project, this id should be regenerated (delete the
+ // field and run `zig build`) if the upstream project is still maintained.
+ // Otherwise, the fork is *hostile*, attempting to take control over the
+ // original project's identity. Thus it is recommended to leave the comment
+ // on the following line intact, so that it shows up in code reviews that
+ // modify the field.
+ .fingerprint = 0x7a754f1e8a3cfd87, // Changing this has security and trust implications.
+ // Tracks the earliest Zig version that the package considers to be a
+ // supported use case.
+ .minimum_zig_version = "0.15.2",
+ // This field is optional.
+ // Each dependency must either provide a `url` and `hash`, or a `path`.
+ // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
+ // Once all dependencies are fetched, `zig build` no longer requires
+ // internet connectivity.
+ .dependencies = .{
+ // See `zig fetch --save <url>` for a command-line interface for adding dependencies.
+ //.example = .{
+ // // When updating this field to a new URL, be sure to delete the corresponding
+ // // `hash`, otherwise you are communicating that you expect to find the old hash at
+ // // the new URL. If the contents of a URL change this will result in a hash mismatch
+ // // which will prevent zig from using it.
+ // .url = "https://example.com/foo.tar.gz",
+ //
+ // // This is computed from the file contents of the directory of files that is
+ // // obtained after fetching `url` and applying the inclusion rules given by
+ // // `paths`.
+ // //
+ // // This field is the source of truth; packages do not come from a `url`; they
+ // // come from a `hash`. `url` is just one of many possible mirrors for how to
+ // // obtain a package matching this `hash`.
+ // //
+ // // Uses the [multihash](https://multiformats.io/multihash/) format.
+ // .hash = "...",
+ //
+ // // When this is provided, the package is found in a directory relative to the
+ // // build root. In this case the package's hash is irrelevant and therefore not
+ // // computed. This field and `url` are mutually exclusive.
+ // .path = "foo",
+ //
+ // // When this is set to `true`, a package is declared to be lazily
+ // // fetched. This makes the dependency only get fetched if it is
+ // // actually used.
+ // .lazy = false,
+ //},
+ },
+ // Specifies the set of files and directories that are included in this package.
+ // Only files and directories listed here are included in the `hash` that
+ // is computed for this package. Only files listed here will remain on disk
+ // when using the zig package manager. As a rule of thumb, one should list
+ // files required for compilation plus any license(s).
+ // Paths are relative to the build root. Use the empty string (`""`) to refer to
+ // the build root itself.
+ // A directory listed here means that all files within, recursively, are included.
+ .paths = .{
+ "build.zig",
+ "build.zig.zon",
+ "src",
+ // For example...
+ //"LICENSE",
+ //"README.md",
+ },
+}
diff --git a/linker.ld b/linker.ld
@@ -0,0 +1,40 @@
+/*
+ * this is a trivial "linker script" given to the linker
+ * and is used to control how the program is linked together.
+ *
+ * the main important thing for us is that we want the program
+ * to be linked starting at 0x8000. the reason: by default the
+ * pi-install bootloader will copy the program it receives
+ * to address 0x8000 and jump to it.
+ */
+SECTIONS
+{
+ /* link the code first at 0x8000. */
+ .text 0x8000 : {
+ *(.text*)
+ . = ALIGN(8);
+ }
+
+ /* read-only data */
+ .rodata : {
+ *(.rodata*)
+ . = ALIGN(8);
+ }
+ /* rw data */
+ .data : {
+ *(.data*)
+ . = ALIGN(8);
+ }
+
+ /* 0 data */
+ .bss : {
+ *(.bss*)
+ . = ALIGN(8);
+ }
+
+ /* discard debug info so the .lists are smaller */
+ /DISCARD/ : { *(.debug*) }
+ /DISCARD/ : { *(.comment*) }
+ /DISCARD/ : { *(*.attributes*) }
+ /DISCARD/ : { *(*.ARM.exidx*) }
+}
diff --git a/src/main.zig b/src/main.zig
@@ -0,0 +1,3 @@
+const util = @import("util.zig");
+
+pub fn main() void {}
diff --git a/src/root.zig b/src/root.zig
@@ -0,0 +1,29 @@
+const std = @import("std");
+const fake_main = @import("main.zig").main;
+
+export fn abort() noreturn {
+ @branchHint(.cold);
+ while (true) {}
+}
+
+fn panic_handler(msg: []const u8, trace_addr: ?usize) noreturn {
+ _ = msg;
+ _ = trace_addr;
+ abort();
+}
+
+pub const panic = std.debug.FullPanic(panic_handler);
+
+// Can't just use main.zig#main directly
+export fn main() void {
+ _ = fake_main();
+}
+
+export fn _start() callconv(.naked) noreturn {
+ // TODO; ask prof why
+ asm volatile (
+ \\ mov sp, 0x800000
+ \\ bl main
+ \\ bl abort
+ );
+}
diff --git a/src/util.zig b/src/util.zig
@@ -0,0 +1,18 @@
+pub fn get_32(addr: *u32) u32 {
+ return asm ("ldr %[result], %[addr]"
+ : [result] "=r" (-> u32),
+ : [addr] "m" (addr),
+ );
+}
+
+pub fn put_32(addr: *u32, value: u32) void {
+ asm volatile ("str %[value], %[addr]"
+ :
+ : [value] "r" (value),
+ [addr] "m" (addr),
+ );
+}
+
+pub fn nop() void {
+ asm volatile ("bx lr");
+}
