2 * \file sn_comparator.h
3 * \brief The sn_comparator_t class and associated methods.
6 * libsortnetwork - src/sn_comparator.h
7 * Copyright (C) 2008-2010 Florian octo Forster
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the
11 * Free Software Foundation; only version 2 of the License is applicable.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License along
19 * with this program; if not, write to the Free Software Foundation, Inc.,
20 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
23 * Florian octo Forster <ff at octo.it>
27 #ifndef SN_COMPARATOR_H
28 #define SN_COMPARATOR_H 1
31 * Struct representing a comparator. Don't access the members of this struct
32 * directly, use the macros below instead.
34 struct sn_comparator_s
36 int min; /**< Index of the line onto which the smaller element will be put. */
37 int max; /**< Index of the line onto which the larger element will be put. */
38 void *user_data; /**< Pointer to user data. */
39 void (*free_func) (void *); /**< Pointer to a function used to free the user data pointer. */
41 typedef struct sn_comparator_s sn_comparator_t;
43 /** Returns the "left" line, i.e. the line with the smaller index. */
44 #define SN_COMP_LEFT(c) (((c)->min < (c)->max) ? (c)->min : (c)->max)
45 /** Returns the "right" line, i.e. the line with the larger index. */
46 #define SN_COMP_RIGHT(c) (((c)->min > (c)->max) ? (c)->min : (c)->max)
47 /** Returns the index of the line onto which the smaller element will be put. */
48 #define SN_COMP_MIN(c) (c)->min
49 /** Returns the index of the line onto which the larger element will be put. */
50 #define SN_COMP_MAX(c) (c)->max
52 /** Expands to the user data pointer. */
53 #define SN_COMP_USER_DATA(c) (c)->user_data
54 /** Expands to the free-function pointer. */
55 #define SN_COMP_FREE_FUNC(c) (c)->free_func
58 * Allocates, initializes and returns a new comparator object. The returned
59 * pointer must be freed by sn_comparator_destroy().
61 * \param min Index of the line onto which the smaller element will be put.
62 * \param max Index of the line onto which the larger element will be put.
63 * \return The newly allocated object or \c NULL on failure.
65 sn_comparator_t *sn_comparator_create (int min, int max);
68 * Destroys a comparator object, freeing all allocated space.
70 * \param c Pointer to the comparator object. This pointer must be allocated by
71 * sn_comparator_create().
73 void sn_comparator_destroy (sn_comparator_t *c);
76 * Inverts a comparator by switching the minimum and maximum indexes stored in
79 * \param c Pointer to the comparator.
81 void sn_comparator_invert (sn_comparator_t *c);
84 * Shifts the indexes stored in the comparator by a constant offset. If the
85 * index becomes too large, it will "wrap around".
87 * \param c The comparator to modify.
88 * \param sw The offset by which to shift the indexes.
89 * \param inputs_num The number of lines / inputs of the comparator network.
90 * This number is used to wrap large indexes around.
92 void sn_comparator_shift (sn_comparator_t *c, int sw, int inputs_num);
95 * Swaps two line indexes by replacing all occurrences of one index with
96 * another index and vice versa. If the comparator does not touch either line,
99 * \param c The comparator to modify.
100 * \param con0 Index of the first line.
101 * \param con1 Index of the second line.
103 void sn_comparator_swap (sn_comparator_t *c, int con0, int con1);
106 * Compares two comparators and returns less than zero, zero, or greater than
107 * zero if the first comparator is smaller than, equal to or larger than the
108 * second comparator, respectively.
110 * \param c0 Pointer to the first comparator.
111 * \param c1 Pointer to the second comparator.
113 int sn_comparator_compare (const sn_comparator_t *c0,
114 const sn_comparator_t *c1);
116 #endif /* SN_COMPARATOR_H */
118 /* vim: set shiftwidth=2 softtabstop=2 : */