//
// Filename: isqrt.nac
// Purpose : N-address code (NAC) implementation for an integer square root 
//           approximation algorithm.
// Author  : Nikolaos Kavvadias (C) 2009, 2010
// Date    : 27-Oct-2009
// Revision: 0.3.0 (27/10/09)
//           Initial version.
// 

//constant u16 0, 1, 2, 16384;

procedure isqrt (in u16 x, out u16 outp)
{
  localvar u16 m, y, a, b;
  localvar u16 t0;
  
S_1:
  a <= mov x;
  m <= ldc 16384;
  y <= ldc 0;
  S_2 <= jmpun;

S_2:
  S_3, S_EXIT <= jmpne m, 0;

S_3:
  b <= ior y, m;
  y <= shr y, 1;
  t0 <= setge a, b;
  S_4, S_5 <= jmpeq t0, 1;

S_4:
  a <= sub a, b; 
  y <= ior y, m; 
  S_5 <= jmpun;

S_5:
  m <= shr m, 2; 
  S_2 <= jmpun;
  
S_EXIT:
  outp <= mov y;
}