port rust tunnel example to zig

examples/rust/build.sh

@@ -1,3 +1,4 @@
-rustc --target=wasm32-unknown-unknown --crate-type cdylib -C opt-level="z" -C "link-args=--import-memory --initial-memory=262144 -zstack-size=65536" -o tunnel.wasm tunnel.rs && \
+rustc --target=wasm32-unknown-unknown --crate-type cdylib -C opt-level="z" -C "link-args=--import-memory --initial-memory=262144 -zstack-size=90000" -o tunnel.wasm tunnel.rs && \
 uw8 filter-exports tunnel.wasm tunnel.wasm && \
-wasm-opt -Oz -o tunnel.wasm tunnel.wasm
+wasm-opt -Oz --strip-producers -o tunnel.wasm tunnel.wasm && \
+uw8 pack -l 9 tunnel.wasm tunnel.uw8

examples/rust/readme.txt

@@ -5,14 +5,14 @@ A nightly rust compiler is needed for the unstable sqrtf32
 intrinsic.
 
 Simply compiling with rustc as shown in build.sh results in a
-371 byte tunnel.wasm. Using wasm-opt this can be reduced to
-260 bytes.
+361 byte tunnel.wasm. Using wasm-opt this can be reduced to
+255 bytes.
 
 When you disassemble this wasm file using wasm2wat you can see
 these globals and exports:
 
-(global (;0;) i32 (i32.const 65536))
-(global (;1;) i32 (i32.const 65536))
+(global (;0;) i32 (i32.const 90000))
+(global (;1;) i32 (i32.const 90000))
 (export "__data_end" (global 0))
 (export "__heap_base" (global 1))
 
@@ -23,5 +23,5 @@ referenced by the exports and we can remove them using
 'uw8 filter-exports' (preferably before running wasm-opt) which
 removes all exports except those used by the MicroW8 platform.
 
-This gives us a 216 byte wasm file. Running this through
+This gives us a 211 byte wasm file. Running this through
 uw8 pack brings us to the final size of 119 bytes.

examples/rust/tunnel.rs

@@ -38,16 +38,21 @@ fn ftoi(v: f32) -> i32 {
 
 #[no_mangle]
 pub fn upd() {
-    for i in 0..320 * 240 {
-        let t = time() * 63 as f32;
+    let mut i: i32 = 0;
+    loop {
+        let t = time() * 63.;
         let x = (i % 320 - 160) as f32;
         let y = (i / 320 - 120) as f32;
-        let d = 40000 as f32 / sqrt(x * x + y * y + 1 as f32);
-        let u = atan2(x, y) * 512f32 / 3.141;
-        let c = (ftoi(d + t * 2 as f32) ^ ftoi(u + t)) as u8 >> 4;
+        let d = 40000 as f32 / sqrt(x * x + y * y + 1.);
+        let u = atan2(x, y) * 512. / 3.141;
+        let c = (ftoi(d + t * 2.) ^ ftoi(u + t)) as u8 >> 4;
         unsafe {
             *((120 + i) as *mut u8) = c;
         }
+        i += 1;
+        if i >= 320*240 {
+            break;
+        }
     }
 }
 

examples/zig/.gitignore

@@ -0,0 +1,2 @@
+/zig-cache/
+/zig-out/

examples/zig/build.zig

@@ -0,0 +1,37 @@
+const std = @import("std");
+
+pub fn build(b: *std.build.Builder) void {
+    const mode = std.builtin.Mode.ReleaseSmall;
+
+    const lib = b.addSharedLibrary("cart", "main.zig", .unversioned);
+    lib.setBuildMode(mode);
+    lib.setTarget(.{ .cpu_arch = .wasm32, .os_tag = .freestanding });
+    lib.import_memory = true;
+    lib.initial_memory = 262144;
+    lib.max_memory = 262144;
+    lib.global_base = 81920;
+    lib.stack_size = 8192;
+    lib.install();
+
+    if (lib.install_step) |install_step| {
+        const run_filter_exports = b.addSystemCommand(&[_][]const u8{
+            "uw8", "filter-exports", "zig-out/lib/cart.wasm", "zig-out/lib/cart-filtered.wasm"
+        });
+        run_filter_exports.step.dependOn(&install_step.step);
+
+        const run_wasm_opt = b.addSystemCommand(&[_][]const u8{
+            "wasm-opt", "-Oz", "-o", "zig-out/cart.wasm", "zig-out/lib/cart-filtered.wasm"
+        });
+        run_wasm_opt.step.dependOn(&run_filter_exports.step);
+
+        const run_uw8_pack = b.addSystemCommand(&[_][]const u8{
+            "uw8", "pack", "-l", "9", "zig-out/cart.wasm", "zig-out/cart.uw8"
+        });
+        run_uw8_pack.step.dependOn(&run_wasm_opt.step);
+
+        const make_opt = b.step("make_opt", "make size optimized cart");
+        make_opt.dependOn(&run_uw8_pack.step);
+
+        b.default_step = make_opt;
+    }
+}

examples/zig/main.zig

@@ -0,0 +1,20 @@
+extern fn atan2(x: f32, y: f32) f32;
+extern fn time() f32;
+
+pub const FRAMEBUFFER: *[320*240]u8 = @intToPtr(*[320*240]u8, 120);
+
+export fn upd() void {
+    var i: u32 = 0;
+    while(true) {
+        var t = time() * 63.0;
+        var x = @intToFloat(f32, (@intCast(i32, i % 320) - 160));
+        var y = @intToFloat(f32, (@intCast(i32, i / 320) - 120));
+        var d = 40000.0 / @sqrt(x * x + y * y + 1.0);
+        var u = atan2(x, y) * 512.0 / 3.141;
+        var c = @intCast(u8, (@floatToInt(i32, d + t * 2.0) ^ @floatToInt(i32, u + t)) & 255) >> 4;
+
+        FRAMEBUFFER[@as(usize, i)] = c;
+        i += 1;
+        if(i >= 320*240) { break; }
+    }
+}