NetBSD/lib/libc/stdlib/radixsort.3

162 lines
4.7 KiB
Groff
Raw Normal View History

1994-06-16 09:26:34 +04:00
.\" Copyright (c) 1990, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
1993-03-21 12:45:37 +03:00
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
1994-06-16 09:26:34 +04:00
.\" from: @(#)radixsort.3 8.2 (Berkeley) 1/27/94
.\" $Id: radixsort.3,v 1.3 1994/06/16 05:26:40 mycroft Exp $
1993-03-21 12:45:37 +03:00
.\"
1994-06-16 09:26:34 +04:00
.Dd January 27, 1994
1993-03-21 12:45:37 +03:00
.Dt RADIXSORT 3
.Os
.Sh NAME
.Nm radixsort
.Nd radix sort
.Sh SYNOPSIS
.Fd #include <limits.h>
.Fd #include <stdlib.h>
.Ft int
1994-06-16 09:26:34 +04:00
.Fn radixsort "u_char **base" "int nmemb" "u_char *table" "u_int endbyte"
.Ft int
.Fn sradixsort "u_char **base" "int nmemb" "u_char *table" "u_int endbyte"
1993-03-21 12:45:37 +03:00
.Sh DESCRIPTION
The
.Fn radixsort
1994-06-16 09:26:34 +04:00
and
.Fn sradixsort
functions
are implementations of radix sort.
1993-03-21 12:45:37 +03:00
.Pp
1994-06-16 09:26:34 +04:00
These functions sort an array of pointers to byte strings, the initial
member of which is referenced by
1993-03-21 12:45:37 +03:00
.Fa base .
The byte strings may contain any values; the end of each string
is denoted by the user-specified value
.Fa endbyte .
.Pp
Applications may specify a sort order by providing the
.Fa table
argument.
If
.Pf non- Dv NULL ,
.Fa table
must reference an array of
.Dv UCHAR_MAX
+ 1 bytes which contains the sort
weight of each possible byte value.
1994-06-16 09:26:34 +04:00
The end-of-string byte must have a sort weight of 0 or 255
(for sorting in reverse order).
1993-03-21 12:45:37 +03:00
More than one byte may have the same sort weight.
The
.Fa table
argument
is useful for applications which wish to sort different characters
1994-06-16 09:26:34 +04:00
equally, for example, providing a table with the same weights
1993-03-21 12:45:37 +03:00
for A-Z as for a-z will result in a case-insensitive sort.
1994-06-16 09:26:34 +04:00
If
.Fa table
is NULL, the contents of the array are sorted in ascending order
according to the
.Tn ASCII
order of the byte strings they reference and
.Fa endbyte
has a sorting weight of 0.
1993-03-21 12:45:37 +03:00
.Pp
The
1994-06-16 09:26:34 +04:00
.Fn sradixsort
function is stable, that is, if two elements compare as equal, their
order in the sorted array is unchanged.
1993-03-21 12:45:37 +03:00
The
1994-06-16 09:26:34 +04:00
.Fn sradixsort
function uses additional memory sufficient to hold
.Fa nmemb
pointers.
.Pp
1993-03-21 12:45:37 +03:00
The
.Fn radixsort
1994-06-16 09:26:34 +04:00
function is not stable, but uses no additional memory.
.Pp
These functions are variants of most-significant-byte radix sorting; in
particular, see D.E. Knuth's Algorithm R and section 5.2.5, exercise 10.
They take linear time relative to the number of bytes in the strings.
1993-03-21 12:45:37 +03:00
.Sh RETURN VALUES
Upon successful completion 0 is returned.
Otherwise, \-1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
1994-06-16 09:26:34 +04:00
.Bl -tag -width Er
.It Bq Er EINVAL
The value of the
.Fa endbyte
element of
.Fa table
is not 0 or 255.
.El
.Pp
Additionally, the
.Fn sradixsort
1993-03-21 12:45:37 +03:00
function
may fail and set
.Va errno
for any of the errors specified for the library routine
.Xr malloc 3 .
.Sh SEE ALSO
.Xr sort 1 ,
.Xr qsort 3
.Pp
.Rs
.%A Knuth, D.E.
.%D 1968
.%B "The Art of Computer Programming"
.%T "Sorting and Searching"
.%V Vol. 3
.%P pp. 170-178
.Re
.Rs
.%A Paige, R.
.%D 1987
.%T "Three Partition Refinement Algorithms"
.%J "SIAM J. Comput."
.%V Vol. 16
.%N No. 6
.Re
1994-06-16 09:26:34 +04:00
.Rs
.%A McIlroy, P.
.%D 1993
.%B "Engineering Radix Sort"
.%T "Computing Systems"
.%V Vol. 6:1
.%P pp. 5-27
.Re
1993-03-21 12:45:37 +03:00
.Sh HISTORY
The
.Fn radixsort
1994-06-16 09:26:34 +04:00
function first appeared in 4.4BSD.