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--- Libc/Libc-262/stdlib/qsort.3
+++ Libc/Libc-594.9.5/stdlib/qsort.3
@@ -34,24 +34,84 @@
.\" SUCH DAMAGE.
.\"
.\" @(#)qsort.3 8.1 (Berkeley) 6/4/93
-.\" $FreeBSD: src/lib/libc/stdlib/qsort.3,v 1.10 2001/09/07 14:46:35 asmodai Exp $
-.\"
-.Dd June 4, 1993
+.\" $FreeBSD: src/lib/libc/stdlib/qsort.3,v 1.15 2004/07/02 23:52:12 ru Exp $
+.\"
+.Dd September 30, 2003
.Dt QSORT 3
.Os
.Sh NAME
-.Nm qsort , heapsort , mergesort
+.Nm heapsort ,
+#ifdef UNIFDEF_BLOCKS
+.Nm heapsort_b ,
+#endif
+.Nm mergesort ,
+#ifdef UNIFDEF_BLOCKS
+.Nm mergesort_b ,
+#endif
+.Nm qsort ,
+#ifdef UNIFDEF_BLOCKS
+.Nm qsort_b ,
+#endif
+.Nm qsort_r
.Nd sort functions
-.Sh LIBRARY
-.Lb libc
.Sh SYNOPSIS
.In stdlib.h
+.Ft int
+.Fo heapsort
+.Fa "void *base"
+.Fa "size_t nel"
+.Fa "size_t width"
+.Fa "int \*[lp]*compar\*[rp]\*[lp]const void *, const void *\*[rp]"
+.Fc
+#ifdef UNIFDEF_BLOCKS
+.Ft int
+.Fo heapsort_b
+.Fa "void *base"
+.Fa "size_t nel"
+.Fa "size_t width"
+.Fa "int \*[lp]^compar\*[rp]\*[lp]const void *, const void *\*[rp]"
+.Fc
+#endif
+.Ft int
+.Fo mergesort
+.Fa "void *base"
+.Fa "size_t nel"
+.Fa "size_t width"
+.Fa "int \*[lp]*compar\*[rp]\*[lp]const void *, const void *\*[rp]"
+.Fc
+#ifdef UNIFDEF_BLOCKS
+.Ft int
+.Fo mergesort_b
+.Fa "void *base"
+.Fa "size_t nel"
+.Fa "size_t width"
+.Fa "int \*[lp]^compar\*[rp]\*[lp]const void *, const void *\*[rp]"
+.Fc
+#endif
.Ft void
-.Fn qsort "void *base" "size_t nmemb" "size_t size" "int (*compar)(const void *, const void *)"
-.Ft int
-.Fn heapsort "void *base" "size_t nmemb" "size_t size" "int (*compar)(const void *, const void *)"
-.Ft int
-.Fn mergesort "void *base" "size_t nmemb" "size_t size" "int (*compar)(const void *, const void *)"
+.Fo qsort
+.Fa "void *base"
+.Fa "size_t nel"
+.Fa "size_t width"
+.Fa "int \*[lp]*compar\*[rp]\*[lp]const void *, const void *\*[rp]"
+.Fc
+#ifdef UNIFDEF_BLOCKS
+.Ft void
+.Fo qsort_b
+.Fa "void *base"
+.Fa "size_t nel"
+.Fa "size_t width"
+.Fa "int \*[lp]^compar\*[rp]\*[lp]const void *, const void *\*[rp]"
+.Fc
+#endif
+.Ft void
+.Fo qsort_r
+.Fa "void *base"
+.Fa "size_t nel"
+.Fa "size_t width"
+.Fa "void *thunk"
+.Fa "int \*[lp]*compar\*[rp]\*[lp]void *, const void *, const void *\*[rp]"
+.Fc
.Sh DESCRIPTION
The
.Fn qsort
@@ -61,7 +121,7 @@
function is a modified selection sort.
The
.Fn mergesort
-function is a modified merge sort with exponential search
+function is a modified merge sort with exponential search,
intended for sorting data with pre-existing order.
.Pp
The
@@ -69,17 +129,19 @@
and
.Fn heapsort
functions sort an array of
-.Fa nmemb
+.Fa nel
objects, the initial member of which is pointed to by
.Fa base .
The size of each object is specified by
-.Fa size .
-.Fn Mergesort
+.Fa width .
+The
+.Fn mergesort
+function
behaves similarly, but
.Em requires
that
-.Fa size
-be greater than
+.Fa width
+be greater than or equal to
.Dq "sizeof(void *) / 2" .
.Pp
The contents of the array
@@ -94,33 +156,58 @@
greater than zero if the first argument is considered to be respectively
less than, equal to, or greater than the second.
.Pp
-The functions
-.Fn qsort
+The
+.Fn qsort_r
+function behaves identically to
+.Fn qsort ,
+except that it takes an additional argument,
+.Fa thunk ,
+which is passed unchanged as the first argument to function pointed to
+.Fa compar .
+This allows the comparison function to access additional
+data without using global variables, and thus
+.Fn qsort_r
+is suitable for use in functions which must be reentrant.
+.Pp
+The algorithms implemented by
+.Fn qsort ,
+.Fn qsort_r ,
and
.Fn heapsort
are
.Em not
-stable, that is, if two members compare as equal, their order in
+stable; that is, if two members compare as equal, their order in
the sorted array is undefined.
-The function
-.Fn mergesort
-is stable.
-.Pp
-The
-.Fn qsort
-function is an implementation of C.A.R. Hoare's ``quicksort'' algorithm,
-a variant of partition-exchange sorting; in particular, see D.E. Knuth's
-Algorithm Q.
-.Fn Qsort
+The
+.Fn mergesort
+algorithm is stable.
+.Pp
+The
+.Fn qsort
+and
+.Fn qsort_r
+functions are an implementation of C.A.R.
+Hoare's
+.Dq quicksort
+algorithm,
+a variant of partition-exchange sorting; in particular, see
+.An D.E. Knuth Ns 's
+.%T "Algorithm Q" .
+.Sy Quicksort
takes O N lg N average time.
This implementation uses median selection to avoid its
O N**2 worst-case behavior.
.Pp
The
.Fn heapsort
-function is an implementation of J.W.J. William's ``heapsort'' algorithm,
-a variant of selection sorting; in particular, see D.E. Knuth's Algorithm H.
-.Fn Heapsort
+function is an implementation of
+.An "J.W.J. William" Ns 's
+.Dq heapsort
+algorithm,
+a variant of selection sorting; in particular, see
+.An "D.E. Knuth" Ns 's
+.%T "Algorithm H" .
+.Sy Heapsort
takes O N lg N worst-case time.
Its
.Em only
@@ -133,49 +220,96 @@
The function
.Fn mergesort
requires additional memory of size
-.Fa nmemb *
-.Fa size
+.Fa nel *
+.Fa width
bytes; it should be used only when space is not at a premium.
-.Fn Mergesort
+The
+.Fn mergesort
+function
is optimized for data with pre-existing order; its worst case
time is O N lg N; its best case is O N.
.Pp
Normally,
.Fn qsort
is faster than
-.Fn mergesort
-is faster than
+.Fn mergesort ,
+which is faster than
.Fn heapsort .
Memory availability and pre-existing order in the data can make this
untrue.
+#ifdef UNIFDEF_BLOCKS
+.Pp
+The
+.Fn heapsort_b ,
+.Fn mergesort_b ,
+and
+.Fn qsort_b
+routines are like the corresponding routines without the _b suffix, expect
+that the
+.Fa compar
+callback is a block pointer instead of a function pointer.
+#endif
.Sh RETURN VALUES
The
-.Fn qsort
-function
-returns no value.
-.Pp
-.Rv -std heapsort mergesort
+#ifdef UNIFDEF_BLOCKS
+.Fn qsort ,
+.Fn qsort_b
+#else
+.Fn qsort
+#endif
+and
+.Fn qsort_r
+functions
+return no value.
+.Pp
+#ifdef UNIFDEF_BLOCKS
+.ds HEAPSORT_B heapsort_b
+.ds MERGESORT_B mergesort_b
+#endif
+.Rv -std heapsort \*[HEAPSORT_B] mergesort \*[MERGESORT_B]
.Sh ERRORS
The
-.Fn heapsort
-and
-.Fn mergesort
+#ifdef UNIFDEF_BLOCKS
+.Fn heapsort ,
+.Fn heapsort_b ,
+.Fn mergesort
+and
+.Fn mergesort_b
+#else
+.Fn heapsort
+and
+.Fn mergesort
+#endif
functions succeed unless:
.Bl -tag -width Er
.It Bq Er EINVAL
The
-.Fa size
+.Fa width
argument is zero, or,
the
-.Fa size
+.Fa width
argument to
.Fn mergesort
+#ifdef UNIFDEF_BLOCKS
+or
+.Fn mergesort_b
+#endif
is less than
.Dq "sizeof(void *) / 2" .
.It Bq Er ENOMEM
-.Fn Heapsort
-or
-.Fn mergesort
+The
+#ifdef UNIFDEF_BLOCKS
+.Fn heapsort ,
+.Fn heapsort_b ,
+.Fn mergesort
+and
+.Fn mergesort_b
+#else
+.Fn heapsort
+and
+.Fn mergesort
+#endif
+functions
were unable to allocate memory.
.El
.Sh COMPATIBILITY
@@ -212,16 +346,19 @@
.%P pp. 114-123, 145-149
.Re
.Rs
-.%A Mcilroy, P.M.
+.%A McIlroy, P.M.
.%T "Optimistic Sorting and Information Theoretic Complexity"
.%J "Fourth Annual ACM-SIAM Symposium on Discrete Algorithms"
.%V January 1992
.Re
.Rs
.%A Bentley, J.L.
+.%A McIlroy, M.D.
.%T "Engineering a Sort Function"
-.%J "bentley@research.att.com"
-.%V January 1992
+.%J "Software--Practice and Experience"
+.%V Vol. 23(11)
+.%P pp. 1249-1265
+.%D November\ 1993
.Re
.Sh STANDARDS
The