Count leading zeros
The clz
instructions, short for count leading zeros, are used to count the amount of zeros at the start of the numbers binary representation.
Try it
(module
(func (export "leading0") (param $num i32) (result i32)
;; load number onto the stack
local.get $num
;; check how many leading zeros and return the result
i32.clz
)
)
const url = "{%wasm-url%}";
await WebAssembly.instantiateStreaming(fetch(url), { console }).then(
(result) => {
const leading0 = result.instance.exports.leading0;
console.log(
`Leading zeros: ${leading0(0b00000000_10000000_00000000_00000000)}`,
);
// Expected output: "Leading zeros: 8"
},
);
Syntax
wasm
;; load a number onto the stack
i32.const 8388608 ;; 00000000_10000000_00000000_00000000
;; count leading zeros
i32.clz
;; the top item on the stack will now be 8
Instruction | Binary opcode |
---|---|
i32.clz |
0x67 |
i64.clz |
0x79 |