/* Copyright (C) 1990, 1993, 1994, 1996, 1998 artofcode LLC.  All rights reserved.
  
  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.,
  59 Temple Place, Suite 330, Boston, MA, 02111-1307.

*/

#ifndef gxarith_INCLUDED
#  define gxarith_INCLUDED

/*$Id: gxarith.h,v 1.2.6.1.2.1 2003/01/17 00:49:03 giles Exp $ */
/* Arithmetic macros for Ghostscript library */

/* Define an in-line abs function, good for any signed numeric type. */
#define any_abs(x) ((x) < 0 ? -(x) : (x))

/* Compute M modulo N.  Requires N > 0; guarantees 0 <= imod(M,N) < N, */
/* regardless of the whims of the % operator for negative operands. */
int imod(P2(int m, int n));

/* Compute the GCD of two integers. */
int igcd(P2(int x, int y));

/*
 * Given A, B, and M, compute X such that A*X = B mod M, 0 < X < M.
 * Requires: M > 0, 0 < A < M, 0 < B < M, gcd(A, M) | gcd(A, B).
 */
int idivmod(P3(int a, int b, int m));

/*
 * Compute floor(log2(N)).  Requires N > 0.
 */
int ilog2(P1(int n));

/* Test whether an integral value fits in a given number of bits. */
/* This works for all integral types. */
#define fits_in_bits(i, n)\
  (sizeof(i) <= sizeof(int) ? fits_in_ubits((i) + (1 << ((n) - 1)), (n) + 1) :\
   fits_in_ubits((i) + (1L << ((n) - 1)), (n) + 1))
#define fits_in_ubits(i, n) (((i) >> (n)) == 0)

/*
 * There are some floating point operations that can be implemented
 * very efficiently on machines that have no floating point hardware,
 * assuming IEEE representation and no range overflows.
 * We define straightforward versions of them here, and alternate versions
 * for no-floating-point machines in gxfarith.h.
 */
/* Test floating point values against constants. */
#define is_fzero(f) ((f) == 0.0)
#define is_fzero2(f1,f2) ((f1) == 0.0 && (f2) == 0.0)
#define is_fneg(f) ((f) < 0.0)
#define is_fge1(f) ((f) >= 1.0)
/* Test whether a floating point value fits in a given number of bits. */
#define f_fits_in_bits(f, n)\
  ((f) >= -2.0 * (1L << ((n) - 2)) && (f) < 2.0 * (1L << ((n) - 2)))
#define f_fits_in_ubits(f, n)\
  ((f) >= 0 && (f) < 4.0 * (1L << ((n) - 2)))

/*
 * Define a macro for computing log2(n), where n=1,2,4,...,128.
 * Because some compilers limit the total size of a statement,
 * this macro must only mention n once.  The macro should really
 * only be used with compile-time constant arguments, but it will work
 * even if n is an expression computed at run-time.
 */
#define small_exact_log2(n)\
 ((uint)(05637042010L >> ((((n) % 11) - 1) * 3)) & 7)

/*
 * The following doesn't give rise to a macro, but is used in several
 * places in Ghostscript.  We observe that if M = 2^n-1 and V < M^2,
 * then the quotient Q and remainder R can be computed as:
 *              Q = V / M = (V + (V >> n) + 1) >> n;
 *              R = V % M = (V + (V / M)) & M = V - (Q << n) + Q.
 */

#endif /* gxarith_INCLUDED */