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/* Operations on HOST_WIDE_INT.

   Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,

   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010

   Free Software Foundation, Inc.

This file is part of GCC.

GCC 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 3, or (at your option) any later

version.

GCC 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 GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#include "config.h"

#include "system.h"

#include "diagnostic-core.h"

#if GCC_VERSION < 3004

/* The functions clz_hwi, ctz_hwi, ffs_hwi, floor_log2 and exact_log2

   are defined as inline functions in hwint.h if GCC_VERSION >= 3004.

   The definitions here are used for older versions of GCC and non-GCC

   bootstrap compilers.  */

/* Given X, an unsigned number, return the largest int Y such that 2**Y <= X.

   If X is 0, return -1.  */

int

floor_log2 (unsigned HOST_WIDE_INT x)

{

  int t = 0;

  if (x == 0)

    return -1;

  if (HOST_BITS_PER_WIDE_INT > 64)

    if (x >= (unsigned HOST_WIDE_INT) 1 << (t + 64))

      t += 64;

  if (HOST_BITS_PER_WIDE_INT > 32)

    if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 32))

      t += 32;

  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 16))

    t += 16;

  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 8))

    t += 8;

  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 4))

    t += 4;

  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 2))

    t += 2;

  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 1))

    t += 1;

  return t;

}

/* Return the logarithm of X, base 2, considering X unsigned,

   if X is a power of 2.  Otherwise, returns -1.  */

int

exact_log2 (unsigned HOST_WIDE_INT x)

{

  if (x != (x & -x))

    return -1;

  return floor_log2 (x);

}

/* Given X, an unsigned number, return the number of least significant bits

   that are zero.  When X == 0, the result is the word size.  */

int

ctz_hwi (unsigned HOST_WIDE_INT x)

{

  return x ? floor_log2 (x & -x) : HOST_BITS_PER_WIDE_INT;

}

/* Similarly for most significant bits.  */

int

clz_hwi (unsigned HOST_WIDE_INT x)

{

  return HOST_BITS_PER_WIDE_INT - 1 - floor_log2(x);

}

/* Similar to ctz_hwi, except that the least significant bit is numbered

   starting from 1, and X == 0 yields 0.  */

int

ffs_hwi (unsigned HOST_WIDE_INT x)

{

  return 1 + floor_log2 (x & -x);

}

#endif /* GCC_VERSION < 3004 */

/* Compute the absolute value of X.  */

HOST_WIDE_INT

abs_hwi (HOST_WIDE_INT x)

{

  gcc_checking_assert (x != HOST_WIDE_INT_MIN);

  return x >= 0 ? x : -x;

}

/* Compute the absolute value of X as an unsigned type.  */

unsigned HOST_WIDE_INT

absu_hwi (HOST_WIDE_INT x)

{

  return x >= 0 ? (unsigned HOST_WIDE_INT)x : -(unsigned HOST_WIDE_INT)x;

}

/* Compute the greatest common divisor of two numbers A and B using

   Euclid's algorithm.  */

HOST_WIDE_INT

gcd (HOST_WIDE_INT a, HOST_WIDE_INT b)

{

  HOST_WIDE_INT x, y, z;

  x = abs_hwi (a);

  y = abs_hwi (b);

  while (x > 0)

    {

      z = y % x;

      y = x;

      x = z;

    }

  return y;

}

/* For X and Y positive integers, return X multiplied by Y and check

   that the result does not overflow.  */

HOST_WIDE_INT

pos_mul_hwi (HOST_WIDE_INT x, HOST_WIDE_INT y)

{

  if (x != 0)

    gcc_checking_assert ((HOST_WIDE_INT_MAX) / x >= y);

  return x * y;

}

/* Return X multiplied by Y and check that the result does not

   overflow.  */

HOST_WIDE_INT

mul_hwi (HOST_WIDE_INT x, HOST_WIDE_INT y)

{

  gcc_checking_assert (x != HOST_WIDE_INT_MIN

                       && y != HOST_WIDE_INT_MIN);

  if (x >= 0)

    {

      if (y >= 0)

        return pos_mul_hwi (x, y);

      return -pos_mul_hwi (x, -y);

    }

  if (y >= 0)

    return -pos_mul_hwi (-x, y);

  return pos_mul_hwi (-x, -y);

}

/* Compute the least common multiple of two numbers A and B .  */

HOST_WIDE_INT

least_common_multiple (HOST_WIDE_INT a, HOST_WIDE_INT b)

{

  return mul_hwi (abs_hwi (a) / gcd (a, b), abs_hwi (b));

}