103 lines
2.4 KiB
C
103 lines
2.4 KiB
C
/* $Id: man_hash.c,v 1.29 2014/12/01 08:05:52 schwarze Exp $ */
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/*
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* Copyright (c) 2008, 2009, 2010 Kristaps Dzonsons <kristaps@bsd.lv>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "config.h"
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#include <sys/types.h>
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#include <assert.h>
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#include <ctype.h>
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#include <limits.h>
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#include <string.h>
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#include "man.h"
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#include "libman.h"
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#define HASH_DEPTH 6
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#define HASH_ROW(x) do { \
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if (isupper((unsigned char)(x))) \
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(x) -= 65; \
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else \
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(x) -= 97; \
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(x) *= HASH_DEPTH; \
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} while (/* CONSTCOND */ 0)
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/*
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* Lookup table is indexed first by lower-case first letter (plus one
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* for the period, which is stored in the last row), then by lower or
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* uppercase second letter. Buckets correspond to the index of the
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* macro (the integer value of the enum stored as a char to save a bit
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* of space).
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*/
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static unsigned char table[26 * HASH_DEPTH];
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/*
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* XXX - this hash has global scope, so if intended for use as a library
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* with multiple callers, it will need re-invocation protection.
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*/
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void
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man_hash_init(void)
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{
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int i, j, x;
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memset(table, UCHAR_MAX, sizeof(table));
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assert(MAN_MAX < UCHAR_MAX);
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for (i = 0; i < (int)MAN_MAX; i++) {
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x = man_macronames[i][0];
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assert(isalpha((unsigned char)x));
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HASH_ROW(x);
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for (j = 0; j < HASH_DEPTH; j++)
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if (UCHAR_MAX == table[x + j]) {
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table[x + j] = (unsigned char)i;
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break;
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}
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assert(j < HASH_DEPTH);
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}
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}
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enum mant
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man_hash_find(const char *tmp)
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{
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int x, y, i;
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enum mant tok;
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if ('\0' == (x = tmp[0]))
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return(MAN_MAX);
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if ( ! (isalpha((unsigned char)x)))
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return(MAN_MAX);
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HASH_ROW(x);
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for (i = 0; i < HASH_DEPTH; i++) {
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if (UCHAR_MAX == (y = table[x + i]))
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return(MAN_MAX);
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tok = (enum mant)y;
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if (0 == strcmp(tmp, man_macronames[tok]))
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return(tok);
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}
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return(MAN_MAX);
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}
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