initial commit

.gitignore

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+/.vscode
+/.zig-cache
+/zig-out

.zigversion

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+0.14.0

build.zig

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+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 {
+    // 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(.{});
+
+    // 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(.{});
+
+    // This creates a "module", which represents a collection of source files alongside
+    // some compilation options, such as optimization mode and linked system libraries.
+    // Every executable or library we compile will be based on one or more modules.
+    const mod = b.addModule("ioutils", .{
+        // `root_source_file` is the Zig "entry point" of the module. If a module
+        // only contains e.g. external object files, you can make this `null`.
+        // In this case the main source file is merely a path, however, in more
+        // complicated build scripts, this could be a generated file.
+        .root_source_file = b.path("src/root.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    // Creates a step for unit testing. This only builds the test executable
+    // but does not run it.
+    const unit_tests = b.addTest(.{
+        .root_module = mod,
+    });
+
+    const run_unit_tests = b.addRunArtifact(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_unit_tests.step);
+}

build.zig.zon

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+.{
+    // 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 = .ioutils,
+
+    // This is a [Semantic Version](https://semver.org/).
+    // In a future version of Zig it will be used for package deduplication.
+    .version = "0.0.1",
+
+    // 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 = 0xe8cdc731c12767c5, // 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 = "0.14.0",
+
+    // 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. 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",
+    },
+}

src/root.zig

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+pub const Error = error {
+    NotAvailable,
+    PermissionDenied,
+};
+
+pub const Permission = enum {
+    readonly,
+    writonly,
+    all,
+};
+
+pub fn Io(comptime T: type) type {
+    return struct {
+        pub fn Map(comptime U: type) type {
+            return struct {
+                base: T.Address,
+
+                pub fn pin(self: *@This(), comptime name: U) *Io(T) {
+                    var io: Io(T) = .{
+                        .address = self.base + @intFromEnum(name),
+                        .permission = .all, // TODO: IO permission
+                    };
+                    return &io;
+                }
+            };
+        }
+
+        address: T.Address,
+        permission: Permission,
+
+        pub fn read(self: *@This()) Error!T.Word {
+            return switch (self.permission) {
+                .writonly => error.PermissionDenied,
+                .readonly, .all => T.read(@ptrCast(@constCast(&self.address))),
+            };
+        }
+
+        pub fn write(self: *@This(), value: T.Word) Error!void {
+            return switch (self.permission) {
+                .readonly => error.PermissionDenied,
+                .writonly, .all => T.write(@ptrCast(@constCast(&self.address)), value),
+            };
+        }
+    };
+}
+
+pub fn BitFields(comptime T: type) type {
+    return packed struct {
+        pub const Bits =
+            if (@typeInfo(T).@"struct".backing_integer) |U| U
+            else @compileError("T must be a packed struct");
+
+        fields: T,
+
+        pub inline fn init(fields: T) @This() {
+            return @bitCast(fields);
+        }
+
+        pub inline fn fromBits(value: Bits) @This() {
+            return .init(@bitCast(value));
+        }
+
+        pub inline fn fromBitsTruncate(value: anytype) @This() {
+            return fromBits(@truncate(value));
+        }
+
+        pub inline fn bits(self: @This()) Bits {
+            return @bitCast(self);
+        }
+
+        pub inline fn cast(self: @This(), comptime U: type) U {
+            return @intCast(self.bits());
+        }
+    };
+}
+
+pub fn Memory(comptime T: type) type {
+    return struct {
+        address: Address,
+
+        pub const Address = usize;
+        pub const Word = T;
+
+        pub fn read(self: *@This()) T {
+            return @as(*T, @ptrFromInt(self.address)).*;
+        }
+
+        pub fn write(self: *@This(), value: T) void {
+            @as(*T, @ptrFromInt(self.address)).* = value;
+        }
+    };
+}