BM(3) | Library Functions Manual | BM(3) |
bm_comp
, bm_exec
,
bm_free
—
#include <sys/types.h>
#include <bm.h>
bm_pat *
bm_comp
(unsigned
char *pattern, size_t
patlen, unsigned char
freq[256]);
unsigned char *
bm_exec
(bm_pat
*pdesc, unsigned char
*text, size_t
len);
void
bm_free
(bm_pat
*pdesc);
bm_comp
() evaluates the
patlen bytes starting at
pattern, and returns a pointer to a structure
describing them. The bytes referenced by pattern may
be of any value.
The search takes advantage of the frequency distribution of the
bytes in the text to be searched. If specified, freq
should be an array of 256 values, with higher values indicating that the
corresponding character occurs more frequently. (A less than optimal
frequency distribution can only result in less than optimal performance, not
incorrect results.) If freq is
NULL
, a system default table is used.
bm_exec
() returns a pointer to the
leftmost occurrence of the string given to bm_comp
()
within text, or NULL
if none
occurs. The number of bytes in text must be specified
by len.
Space allocated for the returned description is discarded by
calling bm_free
() with the returned description as
an argument.
The asymptotic speed of bm_exec
() is
O(len/patlen).
Hume and Sunday, Fast String Searching, Software Practice and Experience, Vol. 21, 11, pp. 1221-48, November 1991.
April 8, 2001 | NetBSD 9.2 |