diff options
Diffstat (limited to 'src/lib/libc/stdlib/qsort.3')
-rw-r--r-- | src/lib/libc/stdlib/qsort.3 | 93 |
1 files changed, 46 insertions, 47 deletions
diff --git a/src/lib/libc/stdlib/qsort.3 b/src/lib/libc/stdlib/qsort.3 index eb122cde12..92c75d5365 100644 --- a/src/lib/libc/stdlib/qsort.3 +++ b/src/lib/libc/stdlib/qsort.3 | |||
@@ -13,11 +13,7 @@ | |||
13 | .\" 2. Redistributions in binary form must reproduce the above copyright | 13 | .\" 2. Redistributions in binary form must reproduce the above copyright |
14 | .\" notice, this list of conditions and the following disclaimer in the | 14 | .\" notice, this list of conditions and the following disclaimer in the |
15 | .\" documentation and/or other materials provided with the distribution. | 15 | .\" documentation and/or other materials provided with the distribution. |
16 | .\" 3. All advertising materials mentioning features or use of this software | 16 | .\" 3. Neither the name of the University nor the names of its contributors |
17 | .\" must display the following acknowledgement: | ||
18 | .\" This product includes software developed by the University of | ||
19 | .\" California, Berkeley and its contributors. | ||
20 | .\" 4. Neither the name of the University nor the names of its contributors | ||
21 | .\" may be used to endorse or promote products derived from this software | 17 | .\" may be used to endorse or promote products derived from this software |
22 | .\" without specific prior written permission. | 18 | .\" without specific prior written permission. |
23 | .\" | 19 | .\" |
@@ -33,14 +29,15 @@ | |||
33 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | 29 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
34 | .\" SUCH DAMAGE. | 30 | .\" SUCH DAMAGE. |
35 | .\" | 31 | .\" |
36 | .\" from: @(#)qsort.3 8.1 (Berkeley) 6/4/93 | 32 | .\" $OpenBSD: qsort.3,v 1.15 2007/05/31 19:19:31 jmc Exp $ |
37 | .\" $Id: qsort.3,v 1.1.1.1 1995/10/18 08:42:18 deraadt Exp $ | ||
38 | .\" | 33 | .\" |
39 | .Dd June 4, 1993 | 34 | .Dd $Mdocdate: May 31 2007 $ |
40 | .Dt QSORT 3 | 35 | .Dt QSORT 3 |
41 | .Os | 36 | .Os |
42 | .Sh NAME | 37 | .Sh NAME |
43 | .Nm qsort, heapsort, mergesort | 38 | .Nm qsort , |
39 | .Nm heapsort , | ||
40 | .Nm mergesort | ||
44 | .Nd sort functions | 41 | .Nd sort functions |
45 | .Sh SYNOPSIS | 42 | .Sh SYNOPSIS |
46 | .Fd #include <stdlib.h> | 43 | .Fd #include <stdlib.h> |
@@ -72,7 +69,7 @@ objects, the initial member of which is pointed to by | |||
72 | .Fa base . | 69 | .Fa base . |
73 | The size of each object is specified by | 70 | The size of each object is specified by |
74 | .Fa size . | 71 | .Fa size . |
75 | .Fn Mergesort | 72 | .Fn mergesort |
76 | behaves similarly, but | 73 | behaves similarly, but |
77 | .Em requires | 74 | .Em requires |
78 | that | 75 | that |
@@ -106,51 +103,49 @@ is stable. | |||
106 | .Pp | 103 | .Pp |
107 | The | 104 | The |
108 | .Fn qsort | 105 | .Fn qsort |
109 | function is an implementation of C.A.R. Hoare's ``quicksort'' algorithm, | 106 | function is an implementation of C.A.R. Hoare's |
107 | .Dq quicksort | ||
108 | algorithm, | ||
110 | a variant of partition-exchange sorting; in particular, see D.E. Knuth's | 109 | a variant of partition-exchange sorting; in particular, see D.E. Knuth's |
111 | Algorithm Q. | 110 | Algorithm Q. |
112 | .Fn Qsort | 111 | .Fn qsort |
113 | takes O N lg N average time. | 112 | takes O N lg N average time. |
114 | This implementation uses median selection to avoid its | 113 | This implementation uses median selection to avoid its |
115 | O N**2 worst-case behavior. | 114 | O N**2 worst-case behavior. |
116 | .Pp | 115 | .Pp |
117 | The | 116 | The |
118 | .Fn heapsort | 117 | .Fn heapsort |
119 | function is an implementation of J.W.J. William's ``heapsort'' algorithm, | 118 | function is an implementation of J.W.J. William's |
119 | .Dq heapsort | ||
120 | algorithm, | ||
120 | a variant of selection sorting; in particular, see D.E. Knuth's Algorithm H. | 121 | a variant of selection sorting; in particular, see D.E. Knuth's Algorithm H. |
121 | .Fn Heapsort | 122 | .Fn heapsort |
122 | takes O N lg N worst-case time. | 123 | takes O N lg N worst-case time. |
123 | Its | 124 | This implementation of |
124 | .Em only | 125 | .Fn heapsort |
125 | advantage over | 126 | is implemented without recursive function calls. |
126 | .Fn qsort | ||
127 | is that it uses almost no additional memory; while | ||
128 | .Fn qsort | ||
129 | does not allocate memory, it is implemented using recursion. | ||
130 | .Pp | 127 | .Pp |
131 | The function | 128 | The function |
132 | .Fn mergesort | 129 | .Fn mergesort |
133 | requires additional memory of size | 130 | requires additional memory of size |
134 | .Fa nmemb * | 131 | .Fa nmemb * |
135 | .Fa size | 132 | .Fa size |
136 | bytes; it should be used only when space is not at a premium. | 133 | bytes; it should be used only when space is not at a premium. |
137 | .Fn Mergesort | 134 | .Fn mergesort |
138 | is optimized for data with pre-existing order; its worst case | 135 | is optimized for data with pre-existing order; its worst case |
139 | time is O N lg N; its best case is O N. | 136 | time is O N lg N; its best case is O N. |
140 | .Pp | 137 | .Pp |
141 | Normally, | 138 | Normally, |
142 | .Fn qsort | 139 | .Fn qsort |
143 | is faster than | 140 | is faster than |
144 | .Fn mergesort | 141 | .Fn mergesort , |
145 | is faster than | 142 | which is faster than |
146 | .Fn heapsort . | 143 | .Fn heapsort . |
147 | Memory availability and pre-existing order in the data can make this | 144 | Memory availability and pre-existing order in the data can make this untrue. |
148 | untrue. | ||
149 | .Sh RETURN VALUES | 145 | .Sh RETURN VALUES |
150 | The | 146 | The |
151 | .Fn qsort | 147 | .Fn qsort |
152 | function | 148 | function returns no value. |
153 | returns no value. | ||
154 | .Pp | 149 | .Pp |
155 | Upon successful completion, | 150 | Upon successful completion, |
156 | .Fn heapsort | 151 | .Fn heapsort |
@@ -163,30 +158,25 @@ is set to indicate the error. | |||
163 | .Sh ERRORS | 158 | .Sh ERRORS |
164 | The | 159 | The |
165 | .Fn heapsort | 160 | .Fn heapsort |
166 | function succeeds unless: | 161 | and |
162 | .Fn mergesort | ||
163 | functions succeed unless: | ||
167 | .Bl -tag -width Er | 164 | .Bl -tag -width Er |
168 | .It Bq Er EINVAL | 165 | .It Bq Er EINVAL |
169 | The | 166 | The |
170 | .Fa size | 167 | .Fa size |
171 | argument is zero, or, | 168 | argument is zero, or the |
172 | the | ||
173 | .Fa size | 169 | .Fa size |
174 | argument to | 170 | argument to |
175 | .Fn mergesort | 171 | .Fn mergesort |
176 | is less than | 172 | is less than |
177 | .Dq "sizeof(void *) / 2" . | 173 | .Dq "sizeof(void *) / 2" . |
178 | .It Bq Er ENOMEM | 174 | .It Bq Er ENOMEM |
179 | .Fn Heapsort | 175 | .Fn heapsort |
180 | or | 176 | or |
181 | .Fn mergesort | 177 | .Fn mergesort |
182 | were unable to allocate memory. | 178 | were unable to allocate memory. |
183 | .El | 179 | .El |
184 | .Sh COMPATIBILITY | ||
185 | Previous versions of | ||
186 | .Fn qsort | ||
187 | did not permit the comparison routine itself to call | ||
188 | .Fn qsort 3 . | ||
189 | This is no longer true. | ||
190 | .Sh SEE ALSO | 180 | .Sh SEE ALSO |
191 | .Xr sort 1 , | 181 | .Xr sort 1 , |
192 | .Xr radixsort 3 | 182 | .Xr radixsort 3 |
@@ -204,7 +194,7 @@ This is no longer true. | |||
204 | .%T "Heapsort" | 194 | .%T "Heapsort" |
205 | .%J "Communications of the ACM" | 195 | .%J "Communications of the ACM" |
206 | .%V 7:1 | 196 | .%V 7:1 |
207 | .%P pp. 347-348 | 197 | .%P pp. 347\-348 |
208 | .Re | 198 | .Re |
209 | .Rs | 199 | .Rs |
210 | .%A Knuth, D.E. | 200 | .%A Knuth, D.E. |
@@ -212,23 +202,32 @@ This is no longer true. | |||
212 | .%B "The Art of Computer Programming" | 202 | .%B "The Art of Computer Programming" |
213 | .%V Vol. 3 | 203 | .%V Vol. 3 |
214 | .%T "Sorting and Searching" | 204 | .%T "Sorting and Searching" |
215 | .%P pp. 114-123, 145-149 | 205 | .%P pp. 114\-123, 145\-149 |
216 | .Re | 206 | .Re |
217 | .Rs | 207 | .Rs |
218 | .%A Mcilroy, P.M. | 208 | .%A McIlroy, P.M. |
219 | .%T "Optimistic Sorting and Information Theoretic Complexity" | 209 | .%T "Optimistic Sorting and Information Theoretic Complexity" |
220 | .%J "Fourth Annual ACM-SIAM Symposium on Discrete Algorithms" | 210 | .%J "Fourth Annual ACM-SIAM Symposium on Discrete Algorithms" |
221 | .%V January 1992 | 211 | .%P pp. 467\-464 |
212 | .%D January 1993 | ||
222 | .Re | 213 | .Re |
223 | .Rs | 214 | .Rs |
224 | .%A Bentley, J.L. | 215 | .%A Bentley, J.L. |
216 | .%A McIlroy, M.D. | ||
225 | .%T "Engineering a Sort Function" | 217 | .%T "Engineering a Sort Function" |
226 | .%J "bentley@research.att.com" | 218 | .%J "Software \- Practice and Experience" |
227 | .%V January 1992 | 219 | .%V Vol. 23(11) |
220 | .%P pp. 1249\-1265 | ||
221 | .%D November 1993 | ||
228 | .Re | 222 | .Re |
229 | .Sh STANDARDS | 223 | .Sh STANDARDS |
224 | Previous versions of | ||
225 | .Fn qsort | ||
226 | did not permit the comparison routine itself to call | ||
227 | .Fn qsort . | ||
228 | This is no longer true. | ||
229 | .Pp | ||
230 | The | 230 | The |
231 | .Fn qsort | 231 | .Fn qsort |
232 | function | 232 | function conforms to |
233 | conforms to | ||
234 | .St -ansiC . | 233 | .St -ansiC . |