1 /* Copyright (C) 1990, 1993, 1994, 1996, 1998 Aladdin Enterprises. All rights reserved. 2 3 This software is provided AS-IS with no warranty, either express or 4 implied. 5 6 This software is distributed under license and may not be copied, 7 modified or distributed except as expressly authorized under the terms 8 of the license contained in the file LICENSE in this distribution. 9 10 For more information about licensing, please refer to 11 http://www.ghostscript.com/licensing/. For information on 12 commercial licensing, go to http://www.artifex.com/licensing/ or 13 contact Artifex Software, Inc., 101 Lucas Valley Road #110, 14 San Rafael, CA 94903, U.S.A., +1(415)492-9861. 15 */ 16 17 #ifndef gxarith_INCLUDED 18 # define gxarith_INCLUDED 19 20 /* $Id: gxarith.h,v 1.5 2002/06/16 08:45:43 lpd Exp $ */ 21 /* Arithmetic macros for Ghostscript library */ 22 23 /* Define an in-line abs function, good for any signed numeric type. */ 24 #define any_abs(x) ((x) < 0 ? -(x) : (x)) 25 26 /* Compute M modulo N. Requires N > 0; guarantees 0 <= imod(M,N) < N, */ 27 /* regardless of the whims of the % operator for negative operands. */ 28 int imod(int m, int n); 29 30 /* Compute the GCD of two integers. */ 31 int igcd(int x, int y); 32 33 /* 34 * Given A, B, and M, compute X such that A*X = B mod M, 0 < X < M. 35 * Requires: M > 0, 0 < A < M, 0 < B < M, gcd(A, M) | gcd(A, B). 36 */ 37 int idivmod(int a, int b, int m); 38 39 /* 40 * Compute floor(log2(N)). Requires N > 0. 41 */ 42 int ilog2(int n); 43 44 /* Test whether an integral value fits in a given number of bits. */ 45 /* This works for all integral types. */ 46 #define fits_in_bits(i, n)\ 47 (sizeof(i) <= sizeof(int) ? fits_in_ubits((i) + (1 << ((n) - 1)), (n) + 1) :\ 48 fits_in_ubits((i) + (1L << ((n) - 1)), (n) + 1)) 49 #define fits_in_ubits(i, n) (((i) >> (n)) == 0) 50 51 /* 52 * There are some floating point operations that can be implemented 53 * very efficiently on machines that have no floating point hardware, 54 * assuming IEEE representation and no range overflows. 55 * We define straightforward versions of them here, and alternate versions 56 * for no-floating-point machines in gxfarith.h. 57 */ 58 /* Test floating point values against constants. */ 59 #define is_fzero(f) ((f) == 0.0) 60 #define is_fzero2(f1,f2) ((f1) == 0.0 && (f2) == 0.0) 61 #define is_fneg(f) ((f) < 0.0) 62 #define is_fge1(f) ((f) >= 1.0) 63 /* Test whether a floating point value fits in a given number of bits. */ 64 #define f_fits_in_bits(f, n)\ 65 ((f) >= -2.0 * (1L << ((n) - 2)) && (f) < 2.0 * (1L << ((n) - 2))) 66 #define f_fits_in_ubits(f, n)\ 67 ((f) >= 0 && (f) < 4.0 * (1L << ((n) - 2))) 68 69 /* 70 * Define a macro for computing log2(n), where n=1,2,4,...,128. 71 * Because some compilers limit the total size of a statement, 72 * this macro must only mention n once. The macro should really 73 * only be used with compile-time constant arguments, but it will work 74 * even if n is an expression computed at run-time. 75 */ 76 #define small_exact_log2(n)\ 77 ((uint)(05637042010L >> ((((n) % 11) - 1) * 3)) & 7) 78 79 /* 80 * The following doesn't give rise to a macro, but is used in several 81 * places in Ghostscript. We observe that if M = 2^n-1 and V < M^2, 82 * then the quotient Q and remainder R can be computed as: 83 * Q = V / M = (V + (V >> n) + 1) >> n; 84 * R = V % M = (V + (V / M)) & M = V - (Q << n) + Q. 85 */ 86 87 #endif /* gxarith_INCLUDED */ 88