Initial commit

.gitignore

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+zig-out/
+zig-cache/

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(.{});
+
+    const lib = b.addStaticLibrary(.{
+        .name = "b64_zig",
+        // 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,
+    });
+
+    // This declares intent for the library to be installed into the standard
+    // location when the user invokes the "install" step (the default step when
+    // running `zig build`).
+    b.installArtifact(lib);
+
+    const exe = b.addExecutable(.{
+        .name = "b64_zig",
+        .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 lib_unit_tests = b.addTest(.{
+        .root_source_file = b.path("src/root.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_lib_unit_tests = b.addRunArtifact(lib_unit_tests);
+
+    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_lib_unit_tests.step);
+    test_step.dependOn(&run_exe_unit_tests.step);
+}

build.zig.zon

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+.{
+    .name = "b64_zig",
+    // 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",
+    },
+}

src/main.zig

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+const std = @import("std");
+
+pub fn main() !void {
+    // Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
+    std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
+
+    // stdout is for the actual output of your application, for example if you
+    // are implementing gzip, then only the compressed bytes should be sent to
+    // stdout, not any debugging messages.
+    const stdout_file = std.io.getStdOut().writer();
+    var bw = std.io.bufferedWriter(stdout_file);
+    const stdout = bw.writer();
+
+    try stdout.print("Run `zig build test` to run the tests.\n", .{});
+
+    try bw.flush(); // don't forget to flush!
+}
+
+test "simple test" {
+    var list = std.ArrayList(i32).init(std.testing.allocator);
+    defer list.deinit(); // try commenting this out and see if zig detects the memory leak!
+    try list.append(42);
+    try std.testing.expectEqual(@as(i32, 42), list.pop());
+}

src/root.zig

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+const std = @import("std");
+const testing = std.testing;
+const GenericReader = std.io.GenericReader;
+const GenericWriter = std.io.GenericWriter;
+
+const b64Error = error{
+    InvalidChar,
+    MissingPad,
+};
+
+pub const b64Alphabet = struct {
+    chars: [64]u8,
+    pad: u8,
+
+    const Self = @This();
+
+    fn getIdx(self: Self, c: u8) b64Error!u6 {
+        for (self.chars, 0..64) |b, i| {
+            if (c == b) {
+                return @intCast(i);
+            }
+        }
+        return b64Error.InvalidChar;
+    }
+
+    fn getchar(self: Self, idx: u6) u8 {
+        return self.chars[idx];
+    }
+
+    fn encodeChunk(self: Self, chunk: [3]u8, len: usize, out: *[4]u8) [4]u8 {
+        var num: u24 = 0;
+        var outbuf = out.*;
+        inline for (0..3) |i| {
+            outbuf[i] = self.pad;
+        }
+        for (0..3) |i| {
+            num <<= 8;
+            if (len > i) {
+                num |= chunk[i];
+            }
+        }
+        var n: u6 = 0;
+        var idx: usize = 4;
+        var outlen = len * 8 / 6;
+        if (len * 8 % 6 > 0) outlen += 1;
+        while (idx > 0) : ({
+            idx -= 1;
+            num >>= 6;
+        }) {
+            if (idx <= outlen) {
+                n = @truncate(num & 0x3f);
+                outbuf[idx - 1] = self.chars[n];
+            } else {
+                outbuf[idx - 1] = self.pad;
+            }
+        }
+        return outbuf;
+    }
+
+    /// Encodes a twelve element array of bytes and returns a sixteen element
+    /// array encoded in base64. This function uses simd instructions to run
+    /// the bitwise operations required for encoding using four parallel vectors
+    /// of bytes.
+    fn encodeChunksVectored(self: Self, in: [12]u8, out: *[16]u8) [16]u8 {
+        var outbuf = out.*;
+        var numvec: @Vector(4, u24) = @splat(0);
+        const shlvec: @Vector(4, usize) = @splat(8);
+        for (0..3) |i| {
+            numvec <<= shlvec;
+            const invec = @Vector(4, u8){ in[i], in[i + 3], in[i + 6], in[i + 9] };
+            numvec |= invec;
+        }
+        const maskvec: @Vector(4, u6) = @splat(0x3f);
+        var idx: usize = 4;
+        const shrvec: @Vector(4, u8) = @splat(6);
+        while (idx > 0) : ({
+            idx -= 1;
+            numvec >>= shrvec;
+        }) {
+            const idxvec = numvec & maskvec;
+            outbuf[idx - 1] = self.chars[idxvec[0]];
+            outbuf[idx + 3] = self.chars[idxvec[1]];
+            outbuf[idx + 7] = self.chars[idxvec[2]];
+            outbuf[idx + 11] = self.chars[idxvec[3]];
+        }
+        return outbuf;
+    }
+
+    fn decodeChunk(self: Self, chunk: [4]u8, out: *[3]u8) b64Error![3]u8 {
+        var num: u24 = 0;
+        var outbuf = out.*;
+        var len: usize = 0;
+        for (chunk) |c| {
+            num <<= 6;
+            if (self.getIdx(c)) |idx| {
+                num |= idx;
+            } else |err| {
+                if (c != self.pad) return err;
+            }
+            len += 1;
+        }
+        var i: usize = 3;
+        var outlen = len * 6 / 8;
+        if (len * 6 % 8 != 0) outlen += 1;
+        while (i > 0) : ({
+            i -= 1;
+            num >>= 8;
+        }) {
+            outbuf[i - 1] = if (i <= outlen) @intCast(num & 0xff) else 0;
+        }
+        return outbuf;
+    }
+
+    fn decodeChunksVectored(self: Self, in: [16]u8, out: *[12]u8) ![12]u8 {
+        var outbuf = out.*;
+        var numvec: @Vector(4, u24) = @splat(0);
+        const shlvec: @Vector(4, usize) = @splat(6);
+        for (0..4) |i| {
+            numvec <<= shlvec;
+            var inarr: [4]u6 = undefined;
+            inarr[0] = try self.getIdx(i);
+            inarr[1] = try self.getIdx(in[i + 4]);
+            inarr[2] = try self.getIdx(in[i + 8]);
+            inarr[3] = try self.getIdx(in[i + 12]);
+            const invec: @Vector(4, u6) = inarr;
+            numvec |= invec;
+        }
+        const maskvec: @Vector(4, u8) = @splat(0xff);
+        const shrvec: @Vector(4, u8) = @splat(8);
+        var idx: usize = 3;
+        while (idx > 0) : ({
+            idx -= 1;
+            numvec >>= shrvec;
+        }) {
+            const cvec = numvec & maskvec;
+            outbuf[idx - 1] = cvec[0];
+            outbuf[idx + 2] = cvec[1];
+            outbuf[idx + 5] = cvec[2];
+            outbuf[idx + 8] = cvec[3];
+        }
+        return outbuf;
+    }
+};
+
+pub const rfc4648B64Alphabet = b64Alphabet{
+    .chars = [64]u8{ 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' },
+    .pad = '=',
+};
+
+test "alphabet getIdx" {
+    try testing.expect(try rfc4648B64Alphabet.getIdx('a') == 26);
+    try testing.expect(try rfc4648B64Alphabet.getIdx('+') == 62);
+}
+
+test "alphabet getChar" {
+    try testing.expect(rfc4648B64Alphabet.getchar(4) == 'E');
+}
+
+test "encode chunk" {
+    const chunk = [3]u8{ 'H', 'e', 'l' };
+    var out: [4]u8 = undefined;
+    const obuf = rfc4648B64Alphabet.encodeChunk(chunk, 3, &out);
+    try testing.expect(std.mem.eql(u8, obuf[0..], "SGVs"));
+}
+
+test "encode chunk 2long" {
+    const chunk = [3]u8{ 'H', 'e', 0 };
+    var out: [4]u8 = undefined;
+    const obuf = rfc4648B64Alphabet.encodeChunk(chunk, 2, &out);
+    try testing.expect(std.mem.eql(u8, obuf[0..], "SGU="));
+}
+
+test "encode chunks vectored" {
+    const chunk = [12]u8{ 'H', 'e', 'l', 'l', 'o', ',', ' ', 'W', 'o', 'r', 'l', 'd' };
+    var out: [16]u8 = undefined;
+    const obuf = rfc4648B64Alphabet.encodeChunksVectored(chunk, &out);
+    try testing.expect(std.mem.eql(u8, obuf[0..], "SGVsbG8sIFdvcmxk"));
+}
+
+test "decode chunk" {
+    const chunk = [4]u8{ 'S', 'G', 'V', 's' };
+    var out: [3]u8 = undefined;
+    const obuf = try rfc4648B64Alphabet.decodeChunk(chunk, &out);
+    try testing.expect(std.mem.eql(u8, obuf[0..], "Hel"));
+}
+
+pub const b64Encoder = struct {
+    reader: GenericReader,
+    writer: GenericWriter,
+    alphabet: b64Alphabet,
+
+    const Self = @This();
+
+    pub fn init(reader: GenericReader, writer: GenericWriter, alphabet: ?b64Alphabet) Self {
+        return Self{
+            .reader = reader,
+            .writer = writer,
+            .alphabet = if (alphabet) |a| a else rfc4648B64Alphabet,
+        };
+    }
+
+    pub fn encode(self: Self) !void {
+        _ = self;
+        // todo
+    }
+};
+
+pub const b64Decoder = struct {
+    reader: std.io.GenericReader,
+    writer: std.io.GenericWriter,
+    alphabet: b64Alphabet,
+
+    const Self = @This();
+
+    pub fn init(reader: GenericReader, writer: GenericWriter, alphabet: b64Alphabet) Self {
+        return Self{
+            .reader = reader,
+            .writer = writer,
+            .alphabet = if (alphabet) |a| a else b64Alphabet,
+        };
+    }
+
+    pub fn decode(self: Self) !void {
+        _ = self;
+        // todo
+    }
+};