144 lines
4.1 KiB
Groff
144 lines
4.1 KiB
Groff
.\" Copyright (c) 1990, 1991 The Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)radixsort.3 5.5 (Berkeley) 4/19/91
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.\"
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.Dd April 19, 1991
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.Dt RADIXSORT 3
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.Os
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.Sh NAME
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.Nm radixsort
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.Nd radix sort
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.Sh SYNOPSIS
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.Fd #include <limits.h>
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.Fd #include <stdlib.h>
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.Ft int
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.Fn radixsort "u_char **base" "int nmemb" "u_char *table" "u_char endbyte"
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.Sh DESCRIPTION
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The
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.Fn radixsort
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function
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is a modified radix sort.
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.Pp
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The
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.Fn radixsort
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function sorts an array of
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.Fa nmemb
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pointers to byte strings, the initial member of which is referenced
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by
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.Fa base .
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The byte strings may contain any values; the end of each string
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is denoted by the user-specified value
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.Fa endbyte .
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The contents of the array are sorted in ascending order according
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to the
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.Tn ASCII
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order of the byte strings they reference.
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.Pp
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Applications may specify a sort order by providing the
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.Fa table
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argument.
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If
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.Pf non- Dv NULL ,
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.Fa table
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must reference an array of
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.Dv UCHAR_MAX
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+ 1 bytes which contains the sort
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weight of each possible byte value.
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The end-of-string byte must have a sort weight of 0.
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More than one byte may have the same sort weight.
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The
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.Fa table
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argument
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is useful for applications which wish to sort different characters
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equally; for example, providing a table with the same weights
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for A-Z as for a-z will result in a case-insensitive sort.
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.Pp
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The
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.Fn radixsort
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function
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is stable, that is, if two elements compare as equal, their order in
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the sorted array is unchanged.
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.Pp
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The
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.Fn radixsort
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function
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is a variant of most-significant-byte radix sorting; in particular, see
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D.E. Knuth's Algorithm R and section 5.2.5, exercise 10.
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The
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.Fn radixsort
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function
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takes linear time relative to the number of bytes in the strings.
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.Sh RETURN VALUES
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Upon successful completion 0 is returned.
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Otherwise, \-1 is returned and the global variable
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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The
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.Fn radixsort
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function
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may fail and set
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.Va errno
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for any of the errors specified for the library routine
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.Xr malloc 3 .
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.Sh SEE ALSO
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.Xr sort 1 ,
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.Xr qsort 3
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.Pp
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.Rs
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.%A Knuth, D.E.
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.%D 1968
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.%B "The Art of Computer Programming"
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.%T "Sorting and Searching"
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.%V Vol. 3
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.%P pp. 170-178
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.Re
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.Rs
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.%A Paige, R.
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.%D 1987
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.%T "Three Partition Refinement Algorithms"
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.%J "SIAM J. Comput."
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.%V Vol. 16
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.%N No. 6
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.Re
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.Sh HISTORY
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The
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.Fn radixsort
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function is
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.Ud .
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.Sh BUGS
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The
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.Fa nmemb
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argument
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must be less than the maximum integer,
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.Dv INT_MAX .
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