3 * Interface to several small and furry utilities. */
6 * GiNaC Copyright (C) 1999 Johannes Gutenberg University Mainz, Germany
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 #ifndef __GINAC_UTILS_H__
24 #define __GINAC_UTILS_H__
29 #include "assertion.h"
31 #ifndef NO_GINAC_NAMESPACE
33 #endif // ndef NO_GINAC_NAMESPACE
36 string ToString(T const & t)
39 ostrstream(buf,sizeof(buf)) << t << ends;
43 unsigned log2(unsigned n);
45 int compare_pointers(void const * a, void const * b);
47 /** Rotate lower 31 bits of unsigned value by one bit to the left
48 * (upper bits get cleared). */
49 inline unsigned rotate_left_31(unsigned n)
51 // clear highest bit and shift 1 bit to the left
52 n=(n & 0x7FFFFFFFU) << 1;
54 // overflow? clear highest bit and set lowest bit
55 if (n & 0x80000000U) {
56 n=(n & 0x7FFFFFFFU) | 0x00000001U;
58 GINAC_ASSERT(n<0x80000000U);
63 /** Golden ratio hash function. */
64 inline unsigned golden_ratio_hash(unsigned n)
66 // This function requires arithmetic with at least 64 significant bits
67 #if SIZEOF_LONG_DOUBLE > 8
68 // If "long double" is bigger than 64 bits, we assume that the mantissa
69 // has at least 64 bits. This is not guaranteed but it's a good guess.
70 const static long double golden_ratio = .618033988749894848204586834370;
71 long double m = golden_ratio * n;
72 return unsigned((m - int(m)) * 0x80000000);
73 #elif SIZEOF_LONG >= 8
74 // "long" has 64 bits, so we prefer it because it might be more efficient
76 unsigned long l = n * 0x4f1bbcddL;
77 return (l & 0x7fffffffU) ^ (l >> 32);
78 #elif SIZEOF_LONG_LONG >= 8
79 // This requires ´long long´ (or an equivalent 64 bit type)---which is,
80 // unfortunately, not ANSI-compliant:
81 unsigned long long l = n * 0x4f1bbcddLL;
82 return (l & 0x7fffffffU) ^ (l >> 32);
84 #error "No 64 bit data type. You lose."
88 // modified from stl_algo.h: always do com(*first1,*first2) instead of comp(*first2,*first1)
89 template <class InputIterator1, class InputIterator2, class OutputIterator,
91 OutputIterator mymerge(InputIterator1 first1, InputIterator1 last1,
92 InputIterator2 first2, InputIterator2 last2,
93 OutputIterator result, Compare comp) {
94 while (first1 != last1 && first2 != last2) {
95 if (comp(*first1, *first2)) {
105 return copy(first2, last2, copy(first1, last1, result));
108 // like merge(), but three lists with *last2<*first3
109 template <class InputIterator1, class InputIterator2, class InputIterator3,
110 class OutputIterator, class Compare>
111 OutputIterator mymerge3(InputIterator1 first1, InputIterator1 last1,
112 InputIterator2 first2, InputIterator2 last2,
113 InputIterator3 first3, InputIterator3 last3,
114 OutputIterator result, Compare comp) {
115 while (first1 != last1 && first2 != last2) {
116 if (comp(*first1, *first2)) {
128 // list1 empty, copy rest of list2, then list3
129 return copy(first3, last3, copy(first2, last2, result));
131 // list2 empty, merge rest of list1 with list3
132 return mymerge(first1,last1,first3,last3,result,comp);
136 #ifndef NO_GINAC_NAMESPACE
138 #endif // ndef NO_GINAC_NAMESPACE
140 #endif // ndef __GINAC_UTILS_H__