/* Copyright (C) 1990, 1993, 1994, 1996, 1998 Aladdin Enterprises.  All rights reserved.

   This file is part of Aladdin Ghostscript.

   Aladdin Ghostscript is distributed with NO WARRANTY OF ANY KIND.  No author
   or distributor accepts any responsibility for the consequences of using it,
   or for whether it serves any particular purpose or works at all, unless he
   or she says so in writing.  Refer to the Aladdin Ghostscript Free Public
   License (the "License") for full details.

   Every copy of Aladdin Ghostscript must include a copy of the License,
   normally in a plain ASCII text file named PUBLIC.  The License grants you
   the right to copy, modify and redistribute Aladdin Ghostscript, but only
   under certain conditions described in the License.  Among other things, the
   License requires that the copyright notice and this notice be preserved on
   all copies.
 */

#ifndef gxarith_INCLUDED
#  define gxarith_INCLUDED

/*$Id: gxarith.h $ */
/* 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 */
