build.zig

const std = @import("std");
const builtin = @import("builtin");
const Build = std.Build;
const Compile = Build.Step.Compile;

// C Source
const source_files = &.{
    "deps/base64/lib/arch/avx512/codec.c",
    "deps/base64/lib/arch/avx2/codec.c",
    "deps/base64/lib/arch/generic/codec.c",
    "deps/base64/lib/arch/neon32/codec.c",
    "deps/base64/lib/arch/neon64/codec.c",
    "deps/base64/lib/arch/ssse3/codec.c",
    "deps/base64/lib/arch/sse41/codec.c",
    "deps/base64/lib/arch/sse42/codec.c",
    "deps/base64/lib/arch/avx/codec.c",
    "deps/base64/lib/lib.c",
    "deps/base64/lib/codec_choose.c",
    "deps/base64/lib/tables/tables.c",
};

fn dir() []const u8 {
    return std.fs.path.dirname(@src().file) orelse ".";
}

pub fn generateConfig(b: *Build) !void {
    const path = try std.fs.path.join(b.allocator, &.{ dir(), "deps/base64/lib/config.h" });
    var file = try std.fs.cwd().createFile(path, .{});
    defer file.close();

    // var buf_writer = std.io.BufferedWriter(64, file.writer());
    var stream = file.writer();

    switch (builtin.cpu.arch) {
        .x86_64 => {
            if (std.Target.x86.featureSetHas(builtin.cpu.features, .avx512vbmi)) {
                _ = try stream.write("#define HAVE_AVX512 1\n");
            } else {
                _ = try stream.write("#define HAVE_AVX512 0\n");
            }
            if (std.Target.x86.featureSetHas(builtin.cpu.features, .avx2)) {
                _ = try stream.write("#define HAVE_AVX2   1\n");
            } else {
                _ = try stream.write("#define HAVE_AVX2   0\n");
            }
            if (std.Target.x86.featureSetHas(builtin.cpu.features, .ssse3)) {
                _ = try stream.write("#define HAVE_SSSE3  1\n");
            } else {
                _ = try stream.write("#define HAVE_SSSE3  0\n");
            }
            if (std.Target.x86.featureSetHas(builtin.cpu.features, .sse4_1)) {
                _ = try stream.write("#define HAVE_SSE41  1\n");
            } else {
                _ = try stream.write("#define HAVE_SSE41  0\n");
            }
            if (std.Target.x86.featureSetHas(builtin.cpu.features, .sse4_2)) {
                _ = try stream.write("#define HAVE_SSE42  1\n");
            } else {
                _ = try stream.write("#define HAVE_SSE42  0\n");
            }
            if (std.Target.x86.featureSetHas(builtin.cpu.features, .avx2)) {
                _ = try stream.write("#define HAVE_AVX    1\n");
            } else {
                _ = try stream.write("#define HAVE_AVX    0\n");
            }
        },
        .arm => {
            if (std.Target.arm.featureSetHas(builtin.cpu.features, .neon)) {
                stream.write("#define HAVE_NEON32 1\n");
                stream.write("#define HAVE_NEON64 1\n");
            } else {
                stream.write("#define HAVE_NEON32 0\n");
                stream.write("#define HAVE_NEON64 0\n");
            }
        },
        else => {},
    }
}

fn buildLibBase64(b: *Build, step: *Compile) !*Compile {
    // Reference:
    // 1. https://github.com/kristoff-it/redis/blob/zig/build.zig
    // 2. https://github.com/natecraddock/ziglua/blob/main/build.zig
    const lib64 = b.addStaticLibrary(.{
        .name = "libbase64",
        .target = step.root_module.resolved_target.?,
        .optimize = step.root_module.optimize.?,
    });
    // For `__stack_chk_fail`
    lib64.linkLibC();
    // C Source
    inline for (source_files) |file| {
        lib64.addCSourceFile(.{
            .file = .{ .path = try std.fs.path.join(b.allocator, &.{ dir(), file }) },
            .flags = &.{
                "-std=c99",
                "-O3",
                "-Wall",
                "-Wextra",
                "-pedantic",
            },
        });
    }
    // config.h
    lib64.addIncludePath(.{ .path = try std.fs.path.join(b.allocator, &.{ dir(), "deps/base64/lib" }) });
    // header
    step.addIncludePath(.{ .path = try std.fs.path.join(b.allocator, &.{ dir(), "deps/base64/include" }) });

    return lib64;
}

pub fn buildAndLink(b: *Build, step: *Compile) !void {
    try generateConfig(b);
    const lib64 = try buildLibBase64(b, step);
    step.linkLibrary(lib64);
}

// 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 = "base64",
        // 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 = .{ .path = "src/lib.zig" },
        .target = target,
        .optimize = optimize,
    });

    buildAndLink(b, lib) catch @panic("build failed");

    // 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);

    // Creates a step for unit testing. This only builds the test executable
    // but does not run it.
    const main_tests = b.addTest(.{
        .root_source_file = .{ .path = "src/lib.zig" },
        .target = target,
        .optimize = optimize,
    });
    buildAndLink(b, main_tests) catch @panic("build failed");

    const run_main_tests = b.addRunArtifact(main_tests);

    // This creates a build step. It will be visible in the `zig build --help` menu,
    // and can be selected like this: `zig build test`
    // This will evaluate the `test` step rather than the default, which is "install".
    const test_step = b.step("test", "Run library tests");
    test_step.dependOn(&run_main_tests.step);

    // Benchmark
    const bench_exe = b.addExecutable(.{
        .name = "bench",
        .root_source_file = .{ .path = "./benchmark/main.zig" },
        .target = target,
        .optimize = optimize,
    });

    const mod = b.addModule("base64", .{
        .root_source_file = .{ .path = "src/lib.zig" },
    });
    mod.addIncludePath(.{ .path = std.fs.path.join(b.allocator, &.{ dir(), "deps/base64/include" }) catch @panic("build failed") });
    bench_exe.root_module.addImport("base64", mod);
    buildAndLink(b, bench_exe) catch @panic("build failed");

    b.installArtifact(bench_exe);
    const run_cmd = b.addRunArtifact(bench_exe);

    run_cmd.step.dependOn(b.getInstallStep());
    const run_step = b.step("bench", "Run the bench mark");
    run_step.dependOn(&run_cmd.step);
}