int
radixsort(
const u_char **base
, int nmemb
, u_char *table
, u_int endbyte
)
int
sradixsort(
const u_char **base
, int nmemb
, u_char *table
, u_int endbyte
)
)
and
sradixsort(
)
functions
are implementations of radix sort.
These functions sort an
nmemb
element array of pointers to byte strings, with
the initial member of which is referenced by
base
.
The byte strings may contain any values.
End of strings is denoted
by character which has same weight as user specified value
endbyte
.
endbyte
has to be between 0 and 255.
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 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
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
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.
EINVAL
]
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).
)
function first appeared in
4.4BSD.