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str_pool.c
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str_pool.c
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/*
* This file is part of libsysperf
*
* Copyright (C) 2001, 2004-2007 by Nokia Corporation.
*
* Contact: Eero Tamminen <eero.tamminen@nokia.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
* This program 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
*/
/* ========================================================================= *
* File: str_pool.c
*
* Author: Simo Piiroinen
*
* -------------------------------------------------------------------------
*
* History:
*
* 29-Jun-2005 Simo Piiroinen
* - cleanup & comments
*
* 21-Jun-2005 Simo Piiroinen
* - initial version
* ========================================================================= */
/* ========================================================================= *
* Includes
* ========================================================================= */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "msg.h"
#include "mem_pool.h"
#include "str_pool.h"
/* ========================================================================= *
* str_pool_t methods
* ========================================================================= */
/* ------------------------------------------------------------------------- *
* str_pool_create
* ------------------------------------------------------------------------- */
str_pool_t *str_pool_create(void)
{
str_pool_t *self = calloc(1, sizeof *self);
str_pool_ctor(self);
return self;
}
/* ------------------------------------------------------------------------- *
* str_pool_delete
* ------------------------------------------------------------------------- */
void str_pool_delete(str_pool_t *self)
{
if( self != 0 )
{
str_pool_dtor(self);
free(self);
}
}
/* ------------------------------------------------------------------------- *
* str_pool_add -- return pointer to interned version of string
* ------------------------------------------------------------------------- */
typedef unsigned int u32;
typedef unsigned char u8;
#include "jhash.h"
const char *str_pool_add(str_pool_t *self, const char *text)
{
/* - - - - - - - - - - - - - - - - - - - *
* Make a word aligned & zero padded to
* multiples of word version of the
* string. This way we can use faster
* version of the hash function.
* - - - - - - - - - - - - - - - - - - - */
size_t len = strlen(text);
size_t size = (len + 3) & ~3;
void *temp = strncpy(alloca(size), text, size);
unsigned hash = jhash2(temp, size>>2, 0);
/* - - - - - - - - - - - - - - - - - - - *
* locate/create a pooled string matching
* the parameter
* - - - - - - - - - - - - - - - - - - - */
unsigned h = hash & (self->hmax-1);
pooled_str_t *p = self->htab[h];
for( ;; p = p->next )
{
if( p == 0 )
{
/* - - - - - - - - - - - - - - - - - - - *
* no match -> create a new entry
* - - - - - - - - - - - - - - - - - - - */
p = mem_pool_alloc(&self->pool, sizeof *p + len);
p->refs = 0;
p->next = self->htab[h];
p->hash = hash;
memcpy(p->text, text, len+1);
self->htab[h] = p;
break;
}
if( p->hash == hash && !strcmp(text, p->text) )
{
/* - - - - - - - - - - - - - - - - - - - *
* found match, use it
* - - - - - - - - - - - - - - - - - - - */
break;
}
}
p->refs += 1;
return p->text;
}
/* ------------------------------------------------------------------------- *
* str_pool_emit -- debugging: dump string pool stats
* ------------------------------------------------------------------------- */
void str_pool_emit(str_pool_t *self, FILE *file)
{
pooled_str_t *s;
int used = 0;
int dmax = 0;
for( unsigned h = 0; h < self->hmax; ++h )
{
int d = 0;
for( s = self->htab[h]; s; s = s->next )
{
d += 1;
fprintf(file, "%6d %8p %08x %s\n", s->refs, s, s->hash, s->text);
}
used += (d != 0);
if( dmax < d ) dmax = d;
}
fprintf(file, "used: %d / %d = %g%%\n", used, self->hmax, 100.0*used/self->hmax);
fprintf(file, "dmax: %d\n", dmax);
}
/* ========================================================================= *
* entry point for testing
* ========================================================================= */
#if 0
int main(int ac, char **av)
{
str_pool_t *pool = str_pool_create();
char buf[1024];
//msg_setverbosity(MSG_WARNING);
while( fgets(buf, sizeof buf, stdin) )
{
buf[strcspn(buf,"\r\n")]=0;
str_pool_add(pool, buf);
//unsigned h = hash_str(buf);
//printf("%08x %s\n", h, buf);
}
str_pool_emit(pool);
str_pool_delete(pool);
return 0;
}
#endif