memory 0 export solution min 1
global cnt as mut f64

; solves knight tour problem
func knight export knight param x as i32 and y as i32 and lv as i32 result i32
local pos as i32
code
  getglobal cnt dconst 1 dadd setglobal cnt
  ; bound check
  get x iconst 8 iges get x iconst 0 ilts ior
  get y iconst 8 iges get y iconst 0 ilts ior ior
  if iconst 0 return end
  
  ; get array index
  get x get y iconst 3 ishl iadd iconst 2 ishl set pos
  
  ; test if a square is visited
  get pos iload align 4 if iconst 0 return end
  get pos get lv istore align 4
  
  ; test if finished
  get lv iconst 64 iges if iconst 1 return end
  
  block
    get lv iconst 1 iadd set lv
    
    ; try every direction
    get x iconst 1 iadd get y iconst 2 iadd get lv call knight brif 0
    get x iconst 2 iadd get y iconst 1 iadd get lv call knight brif 0
    get x iconst 2 iadd get y iconst m1 iadd get lv call knight brif 0
    get x iconst 1 iadd get y iconst m2 iadd get lv call knight brif 0
    get x iconst m1 iadd get y iconst m2 iadd get lv call knight brif 0
    get x iconst m2 iadd get y iconst m1 iadd get lv call knight brif 0
    get x iconst m2 iadd get y iconst 1 iadd get lv call knight brif 0
    get x iconst m1 iadd get y iconst 2 iadd get lv call knight brif 0
    
    ; no moves
    get pos iconst 0 istore align 4
    iconst 0 return
  end
  iconst 1
end

func cnt export getcnt result f64
code
  getglobal cnt
end