MirOS Manual: radixsort(3), sradixsort(3)

RADIXSORT(3)               BSD Programmer's Manual                RADIXSORT(3)

NAME

     radixsort, sradixsort - radix sort

SYNOPSIS

     #include <limits.h>
     #include <stdlib.h>

     int
     radixsort(const u_char **base, int nmemb, const u_char *table,
             u_int endbyte);

     int
     sradixsort(const u_char **base, int nmemb, const u_char *table,
             u_int endbyte);

DESCRIPTION

     The radixsort() and sradixsort() functions are implementations of radix
     sort.

     These functions sort an array of nmemb pointers to byte strings. The ini-
     tial member is referenced by base. The byte strings may contain any
     values; the end of each string is denoted by the user-specified value
     endbyte.

     Applications may specify a sort order by providing the table argument. If
     non-null, table must reference an array of UCHAR_MAX + 1 bytes which con-
     tains the sort weight of each possible byte value. The end-of-string byte
     must have a sort weight of 0 or 255 (for sorting in reverse order). More
     than one byte may have the same sort weight. The table argument is useful
     for applications which wish to sort different characters equally; for ex-
     ample, providing a table with the same weights for A-Z as for a-z will
     result in a case-insensitive sort. If table is NULL, the contents of the
     array are sorted in ascending order according to the ASCII order of the
     byte strings they reference and endbyte has a sorting weight of 0.

     The sradixsort() function is stable; that is, if two elements compare as
     equal, their order in the sorted array is unchanged. The sradixsort()
     function uses additional memory sufficient to hold nmemb pointers.

     The radixsort() function is not stable, but uses no additional memory.

     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.

RETURN VALUES

     Upon successful completion 0 is returned. Otherwise, -1 is returned and
     the global variable errno is set to indicate the error.

ERRORS

     [EINVAL]      The value of the endbyte element of table is not 0 or 255.

     Additionally, the sradixsort() function may fail and set errno for any of
     the errors specified for the library routine malloc(3).

SEE ALSO

     sort(1), qsort(3)

     Knuth, D.E., "Sorting and Searching", The Art of Computer Programming,
     Vol. 3, pp. 170-178, 1968.

     Paige, R., "Three Partition Refinement Algorithms", SIAM J. Comput., No.
     6, Vol. 16, 1987.

     McIlroy, P., "Computing Systems", Engineering Radix Sort, Vol. 6:1, pp.
     5-27, 1993.

HISTORY

     The radixsort() function first appeared in 4.4BSD.

MirOS BSD #10-current          January 27, 1994                              1

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