3 * \brief The sn_stage_t class and associated methods.
6 * libsortnetwork - src/sn_stage.h
7 * Copyright (C) 2008-2010 Florian octo Forster
9 * This library is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU Lesser General Public License as published by
11 * the Free Software Foundation; either version 2.1 of the License, or (at
12 * your option) any later version.
14 * This library is distributed in the hope that it will be useful, but WITHOUT
15 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
16 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
19 * You should have received a copy of the GNU Lesser General Public License
20 * along with this library; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * Florian octo Forster <ff at octo.it>
33 #include "sn_comparator.h"
36 * Struct representing a stage of the comparator network. Don't modify this
37 * struct yourself, use the sn_stage_* methods instead.
41 int depth; /**< Depth of this stage, where zero means closest to the input. */
42 sn_comparator_t *comparators; /**< Pointer to a list of comparators contained in this stage. */
43 int comparators_num; /**< Number of comparators in this stage. */
45 typedef struct sn_stage_s sn_stage_t;
48 * Direction into which to cut.
50 * \see sn_network_cut_at, sn_stage_cut_at
52 enum sn_network_cut_dir_e
54 DIR_MIN, /**< Assume negative infinity. */
55 DIR_MAX /**< Assume positive infinity. */
58 #define SN_STAGE_DEPTH(s) (s)->depth
59 #define SN_STAGE_COMP_NUM(s) (s)->comparators_num
60 #define SN_STAGE_COMP_GET(s,n) ((s)->comparators + (n))
63 * Creates an empty stage and returns a pointer to it. The stage must be freed
64 * using sn_stage_destroy().
66 * \param depth Depth of the stage within the comparator network. This will be
67 * re-set by sn_network_stage_add().
68 * \return Pointer to the comparator network or \c NULL on error.
70 sn_stage_t *sn_stage_create (int depth);
73 * Clones an existing stage.
75 * \param s Stage to clone.
76 * \return Copied stage or \c NULL on error. The returned stage must be freed
77 * using sn_stage_destroy().
79 sn_stage_t *sn_stage_clone (const sn_stage_t *s);
82 * Destroys a stage allocated with sn_stage_create() or one of the other
83 * methods returning a \c sn_stage_t. This frees all allocated space.
85 * \param s The stage to destroy. May be \c NULL.
87 void sn_stage_destroy (sn_stage_t *s);
90 * Applies a stage to an array of integers.
92 * \param s Pointer to the stage.
93 * \param[in,out] values Pointer to integer values to sort. The number of
94 * integer values pointed to must be at least the number of inputs of the
95 * comparator network. Otherwise, segmentation faults or memory corruption
97 * \return Zero on success, non-zero on failure.
98 * \see sn_network_sort
100 int sn_stage_sort (sn_stage_t *s, int *values);
103 * Adds a comparator to a stage. If this would return in a conflict (a
104 * comparator using on of the line already exists in this stage) an error is
107 * \param s Pointer to the stage.
108 * \param c Pointer to a comparator to add. The given comparator is copied. It
109 * is the caller's responsibility to free c.
110 * \return Zero on success, non-zero on failure.
111 * \see sn_stage_comparator_remove
113 int sn_stage_comparator_add (sn_stage_t *s, const sn_comparator_t *c);
117 * Removed a comparator from a stage.
119 * \param s The stage from which to remove the comparator.
120 * \param index The index of the comparator to remove.
121 * \return Zero on success, non-zero on failure.
122 * \see sn_stage_comparator_add
124 int sn_stage_comparator_remove (sn_stage_t *s, int index);
127 * Checks whether the given comparator can be added to a stage, i.e. if neither
128 * line if used by another comparator.
130 * \param s Pointer to the stage.
131 * \param c Pointer to the comparator.
132 * \return Zero if there is no conflict, one if there is a conflict and two if
133 * the comparator is already present in the stage.
135 int sn_stage_comparator_check_conflict (sn_stage_t *s, const sn_comparator_t *c);
138 * Prints the stage to \c STDOUT using a human readable representation.
140 * \param s The comparator network to display.
141 * \return Zero on success, non-zero on failure.
142 * \see sn_network_show
144 int sn_stage_show (sn_stage_t *s);
147 * Inverts a stage by switching the direction of all comparators.
149 * \param s The stage to invert.
150 * \return Zero on success, non-zero on failure.
151 * \see sn_network_invert
153 int sn_stage_invert (sn_stage_t *s);
156 * Shifts a stage (permutes the inputs). Each input is shifted \c sw positions,
157 * higher inputs are "wrapped around".
159 * \param s The stage to shift.
160 * \param sw The number of positions to shift.
161 * \param inputs_num The number of inputs of the comparator network. This value
162 * is used to "wrap around" inputs.
163 * \return Zero on success, non-zero on failure.
165 int sn_stage_shift (sn_stage_t *s, int sw, int inputs_num);
168 * Swaps two lines. This is used by the algorithm used in
169 * sn_network_normalize() to transform non-standard sort networks to standard
172 * \param s The stage on which to operate.
173 * \param con0 Index of the first line.
174 * \param con1 Index of the second line.
175 * \return Zero on success, non-zero on failure.
176 * \see sn_network_normalize(), sn_comparator_swap()
178 int sn_stage_swap (sn_stage_t *s, int con0, int con1);
181 * Removes an input / line by assuming positive or negative infinity is applied
184 * \param s The stage to work with.
185 * \param input The input / line on which is assumed to be positive or negative
187 * \param dir Direction in which to cut; whether positive or negative infinity
189 * \return The new position of the infinite value on success or less than zero
191 * \see sn_network_cut_at
193 int sn_stage_cut_at (sn_stage_t *s, int input, enum sn_network_cut_dir_e dir);
195 /* FIXME: Documentation */
196 int sn_stage_cut (sn_stage_t *s, int *mask, sn_stage_t **prev);
199 * Remove an input from a stage, remove all touching comparators and adapt the
200 * input indexes of all remaining comparators.
202 * \param s The stage from which to remove the input.
203 * \param input The index of the line which to remove.
204 * \return Zero on success, non-zero on failure.
206 int sn_stage_remove_input (sn_stage_t *s, int input);
209 * Reads a stage from a \c FILE pointer and return the newly allocated stage.
211 * \param fh The file handle.
212 * \return Pointer to a newly allocated stage or \c NULL on error.
213 * \see sn_stage_write
215 sn_stage_t *sn_stage_read (FILE *fh);
218 * Writes a stage to a \c FILE pointer.
220 * \param s The stage to write.
221 * \param fh The file handle to write to.
222 * \return Zero on success, non-zero on failure.
225 int sn_stage_write (sn_stage_t *s, FILE *fh);
228 * Creates a serialized form of the given stage. The serialized form is
229 * byte-order independent and can easily be sent over a computer network.
231 * \param s The stage to serialize.
232 * \param[out] ret_buffer Pointer to a pointer into which the location of the
233 * allocated memory will be written. It is the caller's responsibility to
235 * \param[out] ret_buffer_size Pointer to a size_t into which the size of the
236 * allocated memory will be written.
237 * \return Zero on success, non-zero on failure.
238 * \see sn_stage_unserialize(), sn_network_serialize()
240 int sn_stage_serialize (sn_stage_t *s,
241 char **ret_buffer, size_t *ret_buffer_size);
244 * Creates a stage from its serialized form.
246 * \param buffer Pointer to a buffer containing the stage in serialized form.
247 * \param buffer_size Size of the buffer (in bytes).
248 * \return Pointer to the newly allocated stage or \c NULL on error.
249 * \see sn_stage_serialize(), sn_network_unserialize()
251 sn_stage_t *sn_stage_unserialize (char **buffer, size_t *buffer_size);
253 #endif /* SN_STAGE_H */
255 /* vim: set shiftwidth=2 softtabstop=2 : */