minix/lib/libc/stdlib/radixsort.3
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

167 lines
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.\" $NetBSD: radixsort.3,v 1.13 2003/08/07 16:43:43 agc Exp $
.\"
.\" Copyright (c) 1990, 1991, 1993
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.\" 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
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.\" 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
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.\" 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.
.\"
.\" from: @(#)radixsort.3 8.2 (Berkeley) 1/27/94
.\"
.Dd January 27, 1994
.Dt RADIXSORT 3
.Os
.Sh NAME
.Nm radixsort ,
.Nm sradixsort
.Nd radix sort
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In limits.h
.In stdlib.h
.Ft int
.Fn radixsort "const u_char **base" "int nmemb" "u_char *table" "u_int endbyte"
.Ft int
.Fn sradixsort "const u_char **base" "int nmemb" "u_char *table" "u_int endbyte"
.Sh DESCRIPTION
The
.Fn radixsort
and
.Fn sradixsort
functions
are implementations of radix sort.
.Pp
These functions sort an
.Fa nmemb
element array of pointers to byte strings, with
the initial member of which is referenced by
.Fa base .
The byte strings may contain any values.
End of strings is denoted
by character which has same weight as user specified value
.Fa endbyte .
.Fa endbyte
has to be between 0 and 255.
.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.
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
.Fa table
argument
is useful for applications which wish to sort different characters
equally, for example, providing a table with the same weights
for A-Z as for a-z will result in a case-insensitive sort.
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.
.Pp
The
.Fn sradixsort
function is stable, that is, if two elements compare as equal, their
order in the sorted array is unchanged.
The
.Fn sradixsort
function uses additional memory sufficient to hold
.Fa nmemb
pointers.
.Pp
The
.Fn radixsort
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.
.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
.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
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
.Rs
.%A McIlroy, P.
.%D 1993
.%B "Engineering Radix Sort"
.%T "Computing Systems"
.%V Vol. 6:1
.%P pp. 5-27
.Re
.Sh HISTORY
The
.Fn radixsort
function first appeared in
.Bx 4.4 .