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;
+        }
     }
 }