index-of.wat

(module
  (memory (export "memory") 10 10000)

  (func (export "index_of") (param $start i32) (param $end i32) (param $needle i32) (result i32)
    (block $end_loop
      (br_if $end_loop (i32.eq (get_local $start) (get_local $end)))
      (if (i32.eq (i32.load8_u (get_local $start)) (get_local $needle))
        (then (return (get_local $start)))
      )
      (set_local $start (i32.add (i32.const 1) (get_local $start)))
    )
    (i32.const -1)
  )
)