/* -*-C-*-

$Id: fixnum.c,v 9.44 1999/01/02 06:11:34 cph Exp $

Copyright (c) 1987-1999 Massachusetts Institute of Technology

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* Support for fixed point arithmetic.  This should be used instead of
   generic arithmetic when it is desired to tell the compiler to perform
   open coding of fixnum arithmetic.  It is probably a short-term kludge
   that will eventually go away. */

#include "scheme.h"
#include "prims.h"

static long
DEFUN (arg_fixnum, (n), int n)
{
  fast SCHEME_OBJECT argument = (ARG_REF (n));
  if (! (FIXNUM_P (argument)))
    error_wrong_type_arg (n);
  return (FIXNUM_TO_LONG (argument));
}

static long
DEFUN (arg_unsigned_fixnum, (n), int n)
{
  fast SCHEME_OBJECT argument = (ARG_REF (n));
  if (! (FIXNUM_P (argument)))
    error_wrong_type_arg (n);
  return (UNSIGNED_FIXNUM_TO_LONG (argument));
}

/* Predicates */

DEFINE_PRIMITIVE ("FIXNUM?", Prim_zero_fixnum_p, 1, 1, 0)
{
  PRIMITIVE_HEADER (1);
  {
    SCHEME_OBJECT argument = (ARG_REF (1));
    PRIMITIVE_RETURN (BOOLEAN_TO_OBJECT (FIXNUM_P (argument)));
  }
}

DEFINE_PRIMITIVE ("INDEX-FIXNUM?", Prim_index_fixnum_p, 1, 1, 0)
{
  PRIMITIVE_HEADER (1);
  {
    SCHEME_OBJECT argument = (ARG_REF (1));
    PRIMITIVE_RETURN (BOOLEAN_TO_OBJECT (FIXNUM_P (argument) &&
					 FIXNUM_TO_LONG(argument) >= 0));
  }
}

DEFINE_PRIMITIVE ("ZERO-FIXNUM?", Prim_zero_fixnum, 1, 1, 0)
{
  PRIMITIVE_HEADER (1);
  PRIMITIVE_RETURN (BOOLEAN_TO_OBJECT ((arg_fixnum (1)) == 0));
}

DEFINE_PRIMITIVE ("NEGATIVE-FIXNUM?", Prim_negative_fixnum, 1, 1, 0)
{
  PRIMITIVE_HEADER (1);
  PRIMITIVE_RETURN (BOOLEAN_TO_OBJECT ((arg_fixnum (1)) < 0));
}

DEFINE_PRIMITIVE ("POSITIVE-FIXNUM?", Prim_positive_fixnum, 1, 1, 0)
{
  PRIMITIVE_HEADER (1);
  PRIMITIVE_RETURN (BOOLEAN_TO_OBJECT ((arg_fixnum (1)) > 0));
}

DEFINE_PRIMITIVE ("EQUAL-FIXNUM?", Prim_equal_fixnum, 2, 2, 0)
{
  PRIMITIVE_HEADER (2);
  PRIMITIVE_RETURN (BOOLEAN_TO_OBJECT ((arg_fixnum (1)) == (arg_fixnum (2))));
}

DEFINE_PRIMITIVE ("LESS-THAN-FIXNUM?", Prim_less_fixnum, 2, 2, 0)
{
  PRIMITIVE_HEADER (2);
  PRIMITIVE_RETURN (BOOLEAN_TO_OBJECT ((arg_fixnum (1)) < (arg_fixnum (2))));
}

DEFINE_PRIMITIVE ("GREATER-THAN-FIXNUM?", Prim_greater_fixnum, 2, 2, 0)
{
  PRIMITIVE_HEADER (2);
  PRIMITIVE_RETURN (BOOLEAN_TO_OBJECT ((arg_fixnum (1)) > (arg_fixnum (2))));
}

/* Operators */

#define FIXNUM_RESULT(fixnum)						\
{									\
  fast long result = (fixnum);						\
  if (! (LONG_TO_FIXNUM_P (result)))					\
    error_bad_range_arg (1);						\
  PRIMITIVE_RETURN (LONG_TO_FIXNUM (result));				\
}

DEFINE_PRIMITIVE ("ONE-PLUS-FIXNUM", Prim_one_plus_fixnum, 1, 1, 0)
{
  PRIMITIVE_HEADER (1);
  FIXNUM_RESULT ((arg_fixnum (1)) + 1);
}

DEFINE_PRIMITIVE ("MINUS-ONE-PLUS-FIXNUM", Prim_m_1_plus_fixnum, 1, 1, 0)
{
  PRIMITIVE_HEADER (1);
  FIXNUM_RESULT ((arg_fixnum (1)) - 1);
}

DEFINE_PRIMITIVE ("PLUS-FIXNUM", Prim_plus_fixnum, 2, 2, 0)
{
  PRIMITIVE_HEADER (2);
  FIXNUM_RESULT ((arg_fixnum (1)) + (arg_fixnum (2)));
}

DEFINE_PRIMITIVE ("MINUS-FIXNUM", Prim_minus_fixnum, 2, 2, 0)
{
  PRIMITIVE_HEADER (2);
  FIXNUM_RESULT ((arg_fixnum (1)) - (arg_fixnum (2)));
}

DEFINE_PRIMITIVE ("FIXNUM-NEGATE", Prim_fixnum_negate, 1, 1, 0)
{
  PRIMITIVE_HEADER (1);
  FIXNUM_RESULT (- (arg_fixnum (1)));
}

/* Fixnum multiplication routine with overflow detection. */
#include "mul.c"

DEFINE_PRIMITIVE ("MULTIPLY-FIXNUM", Prim_multiply_fixnum, 2, 2, 0)
{
  PRIMITIVE_HEADER (2);
  CHECK_ARG (1, FIXNUM_P);
  CHECK_ARG (2, FIXNUM_P);
  {
    fast long result = (Mul ((ARG_REF (1)), (ARG_REF (2))));
    if (result == SHARP_F)
      error_bad_range_arg (1);
    PRIMITIVE_RETURN (result);
  }
}

DEFINE_PRIMITIVE ("DIVIDE-FIXNUM", Prim_divide_fixnum, 2, 2, 0)
{
  fast long numerator;
  fast long denominator;
  fast long quotient;
  fast long remainder;
  PRIMITIVE_HEADER (2);
  numerator = (arg_fixnum (1));
  denominator = (arg_fixnum (2));
  if (denominator == 0)
    error_bad_range_arg (2);
  /* Now, unbelievable hair because C doesn't fully specify / and %
     when their arguments are negative.  We must get consistent
     answers for all valid arguments. */
  if (numerator < 0)
    {
      numerator = (- numerator);
      if (denominator < 0)
	{
	  denominator = (- denominator);
	  quotient = (numerator / denominator);
	}
      else
	quotient = (- (numerator / denominator));
      remainder = (- (numerator % denominator));
    }
  else
    {
      if (denominator < 0)
	{
	  denominator = (- denominator);
	  quotient = (- (numerator / denominator));
	}
      else
	quotient = (numerator / denominator);
      remainder = (numerator % denominator);
    }
  if (! (LONG_TO_FIXNUM_P (quotient)))
    error_bad_range_arg (1);
  PRIMITIVE_RETURN
    (cons ((LONG_TO_FIXNUM (quotient)), (LONG_TO_FIXNUM (remainder))));
}

DEFINE_PRIMITIVE ("FIXNUM-QUOTIENT", Prim_fixnum_quotient, 2, 2, 0)
{
  PRIMITIVE_HEADER (2);
  {
    fast long numerator = (arg_fixnum (1));
    fast long denominator = (arg_fixnum (2));
    fast long quotient =
      ((denominator > 0)
       ? ((numerator < 0)
	  ? (- ((- numerator) / denominator))
	  : (numerator / denominator))
       : (denominator < 0)
       ? ((numerator < 0)
	  ? ((- numerator) / (- denominator))
	  : (- (numerator / (- denominator))))
       : (error_bad_range_arg (2), 0));
    if (! (LONG_TO_FIXNUM_P (quotient)))
      error_bad_range_arg (1);
    PRIMITIVE_RETURN (LONG_TO_FIXNUM (quotient));
  }
}

DEFINE_PRIMITIVE ("FIXNUM-REMAINDER", Prim_fixnum_remainder, 2, 2, 0)
{
  PRIMITIVE_HEADER (2);
  {
    fast long numerator = (arg_fixnum (1));
    fast long denominator = (arg_fixnum (2));
    PRIMITIVE_RETURN
      (LONG_TO_FIXNUM
       ((denominator > 0)
	? ((numerator < 0)
	   ? (- ((- numerator) % denominator))
	   : (numerator % denominator))
	: (denominator < 0)
	? ((numerator < 0)
	   ? (- ((- numerator) % (- denominator)))
	   : (numerator % (- denominator)))
	: (error_bad_range_arg (2), 0)));
  }
}

DEFINE_PRIMITIVE ("GCD-FIXNUM", Prim_gcd_fixnum, 2, 2, 0)
{
  fast long x;
  fast long y;
  fast long z;
  PRIMITIVE_HEADER (2);
  x = (arg_fixnum (1));
  y = (arg_fixnum (2));
  if (x < 0) x = (-x);
  if (y < 0) y = (-y);
  while (y != 0)
    {
      z = x;
      x = y;
      y = (z % y);
    }
  PRIMITIVE_RETURN (LONG_TO_FIXNUM (x));
}

/* Bitwise operations */

#define FIXNUM_BOOLEAN_BODY(operation)					\
do									\
{									\
  fast unsigned long x, y, z;						\
									\
  PRIMITIVE_HEADER (2);							\
									\
  x = (arg_unsigned_fixnum (1));					\
  y = (arg_unsigned_fixnum (2));					\
									\
  z = (x operation y);							\
  return (LONG_TO_FIXNUM (z));						\
} while (0)


DEFINE_PRIMITIVE ("FIXNUM-ANDC", Prim_fixnum_andc, 2, 2, 0)
{
  FIXNUM_BOOLEAN_BODY(& ~);
}


DEFINE_PRIMITIVE ("FIXNUM-AND", Prim_fixnum_and, 2, 2, 0)
{
  FIXNUM_BOOLEAN_BODY(&);
}


DEFINE_PRIMITIVE ("FIXNUM-OR", Prim_fixnum_or, 2, 2, 0)
{
  FIXNUM_BOOLEAN_BODY(|);
}


DEFINE_PRIMITIVE ("FIXNUM-XOR", Prim_fixnum_xor, 2, 2, 0)
{
  FIXNUM_BOOLEAN_BODY(^);
}


DEFINE_PRIMITIVE ("FIXNUM-NOT", Prim_fixnum_not, 1, 1, 0)
{
  fast unsigned long x, z;

  PRIMITIVE_HEADER (1);

  x = (arg_unsigned_fixnum (1));

  z = (~ (x));
  return (LONG_TO_FIXNUM (z));
}

DEFINE_PRIMITIVE ("FIXNUM-LSH", Prim_fixnum_lsh, 2, 2, 0)
{
  fast unsigned long x, z;
  fast long y;

  PRIMITIVE_HEADER (2);

  x = (arg_unsigned_fixnum (1));
  y = (arg_fixnum (2));

  if (y < 0)
  {
    z = ((y < (- FIXNUM_LENGTH)) ? 0 : (x >> (- y)));
  }
  else
  {
    z = ((y > FIXNUM_LENGTH) ? 0 : (x << y));
  }
  return (LONG_TO_FIXNUM (z));
}


DEFINE_PRIMITIVE ("FIXNUM->FLONUM", Prim_fixnum_to_flonum, 1, 1,
"(FIXNUM)\n\
Equivalent to (INTEGER->FLONUM FIXNUM 2)")
{
  PRIMITIVE_HEADER (1);
  {
    PRIMITIVE_RETURN (double_to_flonum ((double) (arg_fixnum (1))));
  }
}