# Divide polynomials



Eval_quotient = ->
  push(cadr(p1));      # 1st arg, p(x)
  Eval()

  push(caddr(p1));    # 2nd arg, q(x)
  Eval()

  push(cadddr(p1));    # 3rd arg, x
  Eval()

  p1 = pop();      # default x
  if (p1 == symbol(NIL))
    p1 = symbol(SYMBOL_X)
  push(p1)

  divpoly()

#-----------------------------------------------------------------------------
#
#  Divide polynomials
#
#  Input:    tos-3    Dividend
#
#      tos-2    Divisor
#
#      tos-1    x
#
#  Output:    tos-1    Quotient
#
#-----------------------------------------------------------------------------

#define DIVIDEND p1
#define DIVISOR p2
#define X p3
#define Q p4
#define QUOTIENT p5

divpoly = ->
  h = 0
  i = 0
  m = 0
  n = 0
  x = 0
  #U **dividend, **divisor

  save()

  p3 = pop()
  p2 = pop()
  p1 = pop()

  h = tos

  dividend = tos

  m = coeff(p3, p1) - 1;  # m is dividend's power

  divisor = tos

  n = coeff(p3, p2) - 1;  # n is divisor's power

  x = m - n

  push_integer(0)
  p5 = pop()

  while (x >= 0)

    push(stack[dividend+m])
    push(stack[divisor+n])
    divide()
    p4 = pop()

    for i in [0..n]
      push(stack[dividend+x + i])
      push(stack[divisor+i])
      push(p4)
      multiply()
      subtract()
      stack[dividend+x + i] = pop()

    push(p5)
    push(p4)
    push(p3)
    push_integer(x)
    power()
    multiply()
    add()
    p5 = pop()

    m--
    x--

  moveTos h

  push(p5)

  restore()