1 /* Copyright (C) 1990, 1993, 1994, 1996, 1998 artofcode LLC. All rights reserved. 2 3 This program is free software; you can redistribute it and/or modify it 4 under the terms of the GNU General Public License as published by the 5 Free Software Foundation; either version 2 of the License, or (at your 6 option) any later version. 7 8 This program is distributed in the hope that it will be useful, but 9 WITHOUT ANY WARRANTY; without even the implied warranty of 10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 General Public License for more details. 12 13 You should have received a copy of the GNU General Public License along 14 with this program; if not, write to the Free Software Foundation, Inc., 15 59 Temple Place, Suite 330, Boston, MA, 02111-1307. 16 17 */ 18 19 #ifndef gxarith_INCLUDED 20 # define gxarith_INCLUDED 21 22 /*$Id: gxarith.h,v 1.2.6.1.2.1 2003/01/17 00:49:03 giles Exp $ */ 23 /* Arithmetic macros for Ghostscript library */ 24 25 /* Define an in-line abs function, good for any signed numeric type. */ 26 #define any_abs(x) ((x) < 0 ? -(x) : (x)) 27 28 /* Compute M modulo N. Requires N > 0; guarantees 0 <= imod(M,N) < N, */ 29 /* regardless of the whims of the % operator for negative operands. */ 30 int imod(P2(int m, int n)); 31 32 /* Compute the GCD of two integers. */ 33 int igcd(P2(int x, int y)); 34 35 /* 36 * Given A, B, and M, compute X such that A*X = B mod M, 0 < X < M. 37 * Requires: M > 0, 0 < A < M, 0 < B < M, gcd(A, M) | gcd(A, B). 38 */ 39 int idivmod(P3(int a, int b, int m)); 40 41 /* 42 * Compute floor(log2(N)). Requires N > 0. 43 */ 44 int ilog2(P1(int n)); 45 46 /* Test whether an integral value fits in a given number of bits. */ 47 /* This works for all integral types. */ 48 #define fits_in_bits(i, n)\ 49 (sizeof(i) <= sizeof(int) ? fits_in_ubits((i) + (1 << ((n) - 1)), (n) + 1) :\ 50 fits_in_ubits((i) + (1L << ((n) - 1)), (n) + 1)) 51 #define fits_in_ubits(i, n) (((i) >> (n)) == 0) 52 53 /* 54 * There are some floating point operations that can be implemented 55 * very efficiently on machines that have no floating point hardware, 56 * assuming IEEE representation and no range overflows. 57 * We define straightforward versions of them here, and alternate versions 58 * for no-floating-point machines in gxfarith.h. 59 */ 60 /* Test floating point values against constants. */ 61 #define is_fzero(f) ((f) == 0.0) 62 #define is_fzero2(f1,f2) ((f1) == 0.0 && (f2) == 0.0) 63 #define is_fneg(f) ((f) < 0.0) 64 #define is_fge1(f) ((f) >= 1.0) 65 /* Test whether a floating point value fits in a given number of bits. */ 66 #define f_fits_in_bits(f, n)\ 67 ((f) >= -2.0 * (1L << ((n) - 2)) && (f) < 2.0 * (1L << ((n) - 2))) 68 #define f_fits_in_ubits(f, n)\ 69 ((f) >= 0 && (f) < 4.0 * (1L << ((n) - 2))) 70 71 /* 72 * Define a macro for computing log2(n), where n=1,2,4,...,128. 73 * Because some compilers limit the total size of a statement, 74 * this macro must only mention n once. The macro should really 75 * only be used with compile-time constant arguments, but it will work 76 * even if n is an expression computed at run-time. 77 */ 78 #define small_exact_log2(n)\ 79 ((uint)(05637042010L >> ((((n) % 11) - 1) * 3)) & 7) 80 81 /* 82 * The following doesn't give rise to a macro, but is used in several 83 * places in Ghostscript. We observe that if M = 2^n-1 and V < M^2, 84 * then the quotient Q and remainder R can be computed as: 85 * Q = V / M = (V + (V >> n) + 1) >> n; 86 * R = V % M = (V + (V / M)) & M = V - (Q << n) + Q. 87 */ 88 89 #endif /* gxarith_INCLUDED */ 90