Pseudorandom Number Generator

https://en.wikipedia.org/wiki/Linear_congruential_generator

Example 1

(module
  (global $seed (import "js" "global") (mut i32))
  (func (export "rand") (result i32)
  (local $s i32)
  (i32.rem_s 
    (i32.add 
      (i32.mul 
        (i32.const 1103515245) 
        (get_global $seed)
      )  
      (i32.const 12345)
    )
    (i32.const 2147483648)
  )
  tee_local $s
  get_local $s
  set_global $seed
))

Example 2

(module
  (func $pow (export "pow") (param $x f32) (param $y f32) (result f32)
    (local $out f32)
    (local $index f32)
    f32.const 1
    set_local $out
    f32.const 1
    set_local $index

    (block $b0
      (loop $l0
        (f32.mul 
          (get_local $out)
          (get_local $x)
        )
        set_local $out

        (f32.add 
          (get_local $index)
          (f32.const 1)
        )
        tee_local $index
        get_local $y
        f32.gt
        br_if 1

        br 0
      )
    )

    get_local $out
  )
  (func $sin (export "sin") (param $x f32) (result f32)
    (f32.sub
      (f32.add
        (f32.sub
          (get_local $x)
          (f32.div 
            (call $pow (get_local $x) (f32.const 3))
            (f32.const 6)
          )
        )
        (f32.div 
          (call $pow (get_local $x) (f32.const 5))
          (f32.const 120)
        )
      )
      (f32.div 
          (call $pow (get_local $x) (f32.const 7))
        (f32.const 5040)
      )
    )
  )
  (func $fract (export "fract") (param $x f32) (result f32)
    (f32.sub
      (get_local $x)
      (f32.floor (get_local $x))
    )
  )
  (func $rand (export "rand") (param $x f32) (result f32)
    (f32.mul 
      (call $sin (get_local $x))
      (f32.const  43758.5453123)
    )
    call $fract
  )
)