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/* $Id: man_hash.c,v 1.9 2010/04/25 16:32:19 schwarze Exp $ */
/*
* Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@kth.se>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include "libman.h"
#define HASH_DEPTH 8
#define HASH_ROW(x) do { \
if ('.' == (x)) \
(x) = 26; \
else if (isupper((u_char)(x))) \
(x) -= 65; \
else \
(x) -= 97; \
(x) *= HASH_DEPTH; \
} while (/* CONSTCOND */ 0)
/*
* Lookup table is indexed first by lower-case first letter (plus one
* for the period, which is stored in the last row), then by lower or
* uppercase second letter. Buckets correspond to the index of the
* macro (the integer value of the enum stored as a char to save a bit
* of space).
*/
static u_char table[27 * HASH_DEPTH];
/*
* XXX - this hash has global scope, so if intended for use as a library
* with multiple callers, it will need re-invocation protection.
*/
void
man_hash_init(void)
{
int i, j, x;
memset(table, UCHAR_MAX, sizeof(table));
assert(/* CONSTCOND */ MAN_MAX < UCHAR_MAX);
for (i = 0; i < MAN_MAX; i++) {
x = man_macronames[i][0];
assert(isalpha((u_char)x) || '.' == x);
HASH_ROW(x);
for (j = 0; j < HASH_DEPTH; j++)
if (UCHAR_MAX == table[x + j]) {
table[x + j] = (u_char)i;
break;
}
assert(j < HASH_DEPTH);
}
}
enum mant
man_hash_find(const char *tmp)
{
int x, y, i;
enum mant tok;
if ('\0' == (x = tmp[0]))
return(MAN_MAX);
if ( ! (isalpha((u_char)x) || '.' == x))
return(MAN_MAX);
HASH_ROW(x);
for (i = 0; i < HASH_DEPTH; i++) {
if (UCHAR_MAX == (y = table[x + i]))
return(MAN_MAX);
tok = (enum mant)y;
if (0 == strcmp(tmp, man_macronames[tok]))
return(tok);
}
return(MAN_MAX);
}
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