位計數

(module

  (func (export "count1s") (param $num i32) (result i32)
    ;; load the number onto the stack
    local.get $num

    ;; count the amount of 1s and return the result
    i32.popcnt
  )

)

const url = "{%wasm-url%}";
await WebAssembly.instantiateStreaming(fetch(url), { console }).then(
  (result) => {
    const count1s = result.instance.exports.count1s;

    console.log(count1s(0b10000010));
    // Expected output: 2
  },
);

;; load a number onto the stack
i32.const 130 ;; 10000010

;; count the 1s
i32.popcnt

;; the top item on the stack will now be 2