examples: Add vfs_console example program

4 files changed, 187 insertions, 0 deletions

diff --git a/examples/vfs_console/.gitignore b/examples/vfs_console/.gitignore
new file mode 100644
index 0000000..bfc5937
--- /dev/null
+++ b/examples/vfs_console/.gitignore
@@ -0,0 +1,6 @@
+# SPDX-FileCopyrightText: 2024 Himbeer <himbeer@disroot.org>
+#
+# SPDX-License-Identifier: CC0-1.0
+
+# zig cache and output
+/zig-*/
diff --git a/examples/vfs_console/build.zig b/examples/vfs_console/build.zig
new file mode 100644
index 0000000..fc07e66
--- /dev/null
+++ b/examples/vfs_console/build.zig
@@ -0,0 +1,79 @@
+// SPDX-FileCopyrightText: Zig contributors
+// SPDX-FileCopyrightText: 2024 Himbeer <himbeer@disroot.org>
+//
+// SPDX-License-Identifier: MIT
+
+const std = @import("std");
+
+// Although this function looks imperative, note that its job is to
+// declaratively construct a build graph that will be executed by an external
+// runner.
+pub fn build(b: *std.Build) void {
+    const riscv64_freestanding = std.zig.CrossTarget{
+        .cpu_arch = .riscv64,
+        .os_tag = .freestanding,
+        .ofmt = .elf,
+    };
+
+    // Standard target options allows the person running `zig build` to choose
+    // what target to build for. Here we do not override the defaults, which
+    // means any target is allowed, and the default is native. Other options
+    // for restricting supported target set are available.
+    const target = b.standardTargetOptions(.{ .whitelist = &[_]std.zig.CrossTarget{riscv64_freestanding}, .default_target = riscv64_freestanding });
+
+    // Standard optimization options allow the person running `zig build` to select
+    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
+    // set a preferred release mode, allowing the user to decide how to optimize.
+    const optimize = b.standardOptimizeOption(.{});
+
+    const exe = b.addExecutable(.{
+        .name = "vfs_console",
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    // This declares intent for the executable to be installed into the
+    // standard location when the user invokes the "install" step (the default
+    // step when running `zig build`).
+    b.installArtifact(exe);
+
+    // This *creates* a Run step in the build graph, to be executed when another
+    // step is evaluated that depends on it. The next line below will establish
+    // such a dependency.
+    const run_cmd = b.addRunArtifact(exe);
+
+    // By making the run step depend on the install step, it will be run from the
+    // installation directory rather than directly from within the cache directory.
+    // This is not necessary, however, if the application depends on other installed
+    // files, this ensures they will be present and in the expected location.
+    run_cmd.step.dependOn(b.getInstallStep());
+
+    // This allows the user to pass arguments to the application in the build
+    // command itself, like this: `zig build run -- arg1 arg2 etc`
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+
+    // This creates a build step. It will be visible in the `zig build --help` menu,
+    // and can be selected like this: `zig build run`
+    // This will evaluate the `run` step rather than the default, which is "install".
+    const run_step = b.step("run", "Run the app");
+    run_step.dependOn(&run_cmd.step);
+
+    // Creates a step for unit testing. This only builds the test executable
+    // but does not run it.
+    const exe_unit_tests = b.addTest(.{
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
+
+    // Similar to creating the run step earlier, this exposes a `test` step to
+    // the `zig build --help` menu, providing a way for the user to request
+    // running the unit tests.
+    const test_step = b.step("test", "Run unit tests");
+    test_step.dependOn(&run_exe_unit_tests.step);
+}
diff --git a/examples/vfs_console/build.zig.zon b/examples/vfs_console/build.zig.zon
new file mode 100644
index 0000000..af589cf
--- /dev/null
+++ b/examples/vfs_console/build.zig.zon
@@ -0,0 +1,71 @@
+// SPDX-FileCopyrightText: Zig contributors
+//
+// SPDX-License-Identifier: MIT
+
+.{
+    .name = "vfs_console",
+    // 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",
+
+    // This field is optional.
+    // This is currently advisory only; Zig does not yet do anything
+    // with this value.
+    //.minimum_zig_version = "0.11.0",
+
+    // 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.
+        //    .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.
+    // 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 = .{
+        // This makes *all* files, recursively, included in this package. It is generally
+        // better to explicitly list the files and directories instead, to insure that
+        // fetching from tarballs, file system paths, and version control all result
+        // in the same contents hash.
+        "",
+        // For example...
+        //"build.zig",
+        //"build.zig.zon",
+        //"src",
+        //"LICENSE",
+        //"README.md",
+    },
+}
diff --git a/examples/vfs_console/src/main.zig b/examples/vfs_console/src/main.zig
new file mode 100644
index 0000000..0ca6d59
--- /dev/null
+++ b/examples/vfs_console/src/main.zig
@@ -0,0 +1,31 @@
+// SPDX-FileCopyrightText: 2024 Himbeer <himbeer@disroot.org>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+const std = @import("std");
+
+export fn _start() void {
+    main();
+}
+
+pub fn main() void {
+    const path = "/io/debug\x00";
+    const handle = asm volatile (
+        \\ li a7, 100001
+        \\ ecall
+        : [handle] "={a0}" (-> usize),
+        : [path] "{a0}" (path.ptr),
+        : "a7", "a1"
+    );
+
+    const msg = "Hello, VFS console!\r\n";
+    asm volatile (
+        \\ li a7, 100010
+        \\ ecall
+        :
+        : [handle] "{a0}" (handle),
+          [bytes] "{a1}" (msg.ptr),
+          [len] "{a2}" (msg.len),
+        : "a7"
+    );
+}