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Diffstat (limited to 'alsa-lib/src/compat/hsearch_r.c')
| -rw-r--r-- | alsa-lib/src/compat/hsearch_r.c | 236 |
1 files changed, 0 insertions, 236 deletions
diff --git a/alsa-lib/src/compat/hsearch_r.c b/alsa-lib/src/compat/hsearch_r.c deleted file mode 100644 index 96ceac1..0000000 --- a/alsa-lib/src/compat/hsearch_r.c +++ /dev/null @@ -1,236 +0,0 @@ -/* Copyright (C) 1993, 1995, 1996, 1997 Free Software Foundation, Inc. - This file is part of the GNU C Library. - Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1993. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public License as - published by the Free Software Foundation; either version 2.1 of the - License, or (at your option) any later version. - - The GNU C Library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library; see the file COPYING.LIB. If not, - write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, - Boston, MA 02111-1307, USA. */ - -#include <errno.h> -#include <malloc.h> -#include <string.h> - -#define __USE_GNU -#ifndef __set_errno -#define __set_errno(e) errno = (e) -#endif -#include <search.h> - -/* [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986 - [Knuth] The Art of Computer Programming, part 3 (6.4) */ - - -/* The reentrant version has no static variables to maintain the state. - Instead the interface of all functions is extended to take an argument - which describes the current status. */ -typedef struct _ENTRY -{ - unsigned int used; - ENTRY entry; -} -_ENTRY; - - -/* For the used double hash method the table size has to be a prime. To - correct the user given table size we need a prime test. This trivial - algorithm is adequate because - a) the code is (most probably) called a few times per program run and - b) the number is small because the table must fit in the core */ -static int -isprime (unsigned int number) -{ - /* no even number will be passed */ - unsigned int div = 3; - - while (div * div < number && number % div != 0) - div += 2; - - return number % div != 0; -} - - -/* Before using the hash table we must allocate memory for it. - Test for an existing table are done. We allocate one element - more as the found prime number says. This is done for more effective - indexing as explained in the comment for the hsearch function. - The contents of the table is zeroed, especially the field used - becomes zero. */ -int -hcreate_r (nel, htab) - size_t nel; - struct hsearch_data *htab; -{ - /* Test for correct arguments. */ - if (htab == NULL) - { - __set_errno (EINVAL); - return 0; - } - - /* There is still another table active. Return with error. */ - if (htab->table != NULL) - return 0; - - /* Change nel to the first prime number not smaller as nel. */ - nel |= 1; /* make odd */ - while (!isprime (nel)) - nel += 2; - - htab->size = nel; - htab->filled = 0; - - /* allocate memory and zero out */ - htab->table = (_ENTRY *) calloc (htab->size + 1, sizeof (_ENTRY)); - if (htab->table == NULL) - return 0; - - /* everything went alright */ - return 1; -} - - -/* After using the hash table it has to be destroyed. The used memory can - be freed and the local static variable can be marked as not used. */ -void -hdestroy_r (htab) - struct hsearch_data *htab; -{ - /* Test for correct arguments. */ - if (htab == NULL) - { - __set_errno (EINVAL); - return; - } - - if (htab->table != NULL) - /* free used memory */ - free (htab->table); - - /* the sign for an existing table is an value != NULL in htable */ - htab->table = NULL; -} - - -/* This is the search function. It uses double hashing with open addressing. - The argument item.key has to be a pointer to an zero terminated, most - probably strings of chars. The function for generating a number of the - strings is simple but fast. It can be replaced by a more complex function - like ajw (see [Aho,Sethi,Ullman]) if the needs are shown. - - We use an trick to speed up the lookup. The table is created by hcreate - with one more element available. This enables us to use the index zero - special. This index will never be used because we store the first hash - index in the field used where zero means not used. Every other value - means used. The used field can be used as a first fast comparison for - equality of the stored and the parameter value. This helps to prevent - unnecessary expensive calls of strcmp. */ -int -hsearch_r (item, action, retval, htab) - ENTRY item; - ACTION action; - ENTRY **retval; - struct hsearch_data *htab; -{ - unsigned int hval; - unsigned int count; - unsigned int len = strlen (item.key); - unsigned int idx; - - /* Compute an value for the given string. Perhaps use a better method. */ - hval = len; - count = len; - while (count-- > 0) - { - hval <<= 4; - hval += item.key[count]; - } - - /* First hash function: simply take the modulo but prevent zero. */ - hval %= htab->size; - if (hval == 0) - ++hval; - - /* The first index tried. */ - idx = hval; - - if (htab->table[idx].used) - { - /* Further action might be required according to the action value. */ - unsigned hval2; - - if (htab->table[idx].used == hval - && strcmp (item.key, htab->table[idx].entry.key) == 0) - { - if (action == ENTER) - htab->table[idx].entry.data = item.data; - - *retval = &htab->table[idx].entry; - return 1; - } - - /* Second hash function, as suggested in [Knuth] */ - hval2 = 1 + hval % (htab->size - 2); - - do - { - /* Because SIZE is prime this guarantees to step through all - available indexes. */ - if (idx <= hval2) - idx = htab->size + idx - hval2; - else - idx -= hval2; - - /* If we visited all entries leave the loop unsuccessfully. */ - if (idx == hval) - break; - - /* If entry is found use it. */ - if (htab->table[idx].used == hval - && strcmp (item.key, htab->table[idx].entry.key) == 0) - { - if (action == ENTER) - htab->table[idx].entry.data = item.data; - - *retval = &htab->table[idx].entry; - return 1; - } - } - while (htab->table[idx].used); - } - - /* An empty bucket has been found. */ - if (action == ENTER) - { - /* If table is full and another entry should be entered return - with error. */ - if (action == ENTER && htab->filled == htab->size) - { - __set_errno (ENOMEM); - *retval = NULL; - return 0; - } - - htab->table[idx].used = hval; - htab->table[idx].entry = item; - - ++htab->filled; - - *retval = &htab->table[idx].entry; - return 1; - } - - __set_errno (ESRCH); - *retval = NULL; - return 0; -} |