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/**************************************************************************
*
* Copyright 2009 VMware, Inc.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
* IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
**************************************************************************/
/**
* @file
* Generic bitmask implementation.
*
* @author Jose Fonseca <jfonseca@vmware.com>
*/
#include "pipe/p_compiler.h"
#include "util/u_debug.h"
#include "util/u_memory.h"
#include "util/u_bitmask.h"
typedef uint32_t util_bitmask_word;
#define UTIL_BITMASK_INITIAL_WORDS 16
#define UTIL_BITMASK_BITS_PER_BYTE 8
#define UTIL_BITMASK_BITS_PER_WORD (sizeof(util_bitmask_word) * UTIL_BITMASK_BITS_PER_BYTE)
struct util_bitmask
{
util_bitmask_word *words;
/** Number of bits we can currently hold */
unsigned size;
/** Number of consecutive bits set at the start of the bitmask */
unsigned filled;
};
struct util_bitmask *
util_bitmask_create(void)
{
struct util_bitmask *bm;
bm = MALLOC_STRUCT(util_bitmask);
if (!bm)
return NULL;
bm->words = (util_bitmask_word *)CALLOC(UTIL_BITMASK_INITIAL_WORDS, sizeof(util_bitmask_word));
if(!bm->words) {
FREE(bm);
return NULL;
}
bm->size = UTIL_BITMASK_INITIAL_WORDS * UTIL_BITMASK_BITS_PER_WORD;
bm->filled = 0;
return bm;
}
/**
* Resize the bitmask if necessary
*/
static inline boolean
util_bitmask_resize(struct util_bitmask *bm,
unsigned minimum_index)
{
unsigned minimum_size = minimum_index + 1;
unsigned new_size;
util_bitmask_word *new_words;
/* Check integer overflow */
if(!minimum_size)
return FALSE;
if(bm->size >= minimum_size)
return TRUE;
assert(bm->size % UTIL_BITMASK_BITS_PER_WORD == 0);
new_size = bm->size;
while(new_size < minimum_size) {
new_size *= 2;
/* Check integer overflow */
if(new_size < bm->size)
return FALSE;
}
assert(new_size);
assert(new_size % UTIL_BITMASK_BITS_PER_WORD == 0);
new_words = (util_bitmask_word *)REALLOC((void *)bm->words,
bm->size / UTIL_BITMASK_BITS_PER_BYTE,
new_size / UTIL_BITMASK_BITS_PER_BYTE);
if (!new_words)
return FALSE;
memset(new_words + bm->size/UTIL_BITMASK_BITS_PER_WORD,
0,
(new_size - bm->size)/UTIL_BITMASK_BITS_PER_BYTE);
bm->size = new_size;
bm->words = new_words;
return TRUE;
}
/**
* Lazily update the filled.
*/
static inline void
util_bitmask_filled_set(struct util_bitmask *bm,
unsigned index)
{
assert(bm->filled <= bm->size);
assert(index < bm->size);
if(index == bm->filled) {
++bm->filled;
assert(bm->filled <= bm->size);
}
}
static inline void
util_bitmask_filled_unset(struct util_bitmask *bm,
unsigned index)
{
assert(bm->filled <= bm->size);
assert(index < bm->size);
if(index < bm->filled)
bm->filled = index;
}
unsigned
util_bitmask_add(struct util_bitmask *bm)
{
unsigned word;
unsigned bit;
util_bitmask_word mask;
assert(bm);
/* linear search for an empty index */
word = bm->filled / UTIL_BITMASK_BITS_PER_WORD;
bit = bm->filled % UTIL_BITMASK_BITS_PER_WORD;
mask = 1 << bit;
while(word < bm->size / UTIL_BITMASK_BITS_PER_WORD) {
while(bit < UTIL_BITMASK_BITS_PER_WORD) {
if(!(bm->words[word] & mask))
goto found;
++bm->filled;
++bit;
mask <<= 1;
}
++word;
bit = 0;
mask = 1;
}
found:
/* grow the bitmask if necessary */
if(!util_bitmask_resize(bm, bm->filled))
return UTIL_BITMASK_INVALID_INDEX;
assert(!(bm->words[word] & mask));
bm->words[word] |= mask;
return bm->filled++;
}
unsigned
util_bitmask_set(struct util_bitmask *bm,
unsigned index)
{
unsigned word;
unsigned bit;
util_bitmask_word mask;
assert(bm);
/* grow the bitmask if necessary */
if(!util_bitmask_resize(bm, index))
return UTIL_BITMASK_INVALID_INDEX;
word = index / UTIL_BITMASK_BITS_PER_WORD;
bit = index % UTIL_BITMASK_BITS_PER_WORD;
mask = 1 << bit;
bm->words[word] |= mask;
util_bitmask_filled_set(bm, index);
return index;
}
void
util_bitmask_clear(struct util_bitmask *bm,
unsigned index)
{
unsigned word;
unsigned bit;
util_bitmask_word mask;
assert(bm);
if(index >= bm->size)
return;
word = index / UTIL_BITMASK_BITS_PER_WORD;
bit = index % UTIL_BITMASK_BITS_PER_WORD;
mask = 1 << bit;
bm->words[word] &= ~mask;
util_bitmask_filled_unset(bm, index);
}
boolean
util_bitmask_get(struct util_bitmask *bm,
unsigned index)
{
unsigned word = index / UTIL_BITMASK_BITS_PER_WORD;
unsigned bit = index % UTIL_BITMASK_BITS_PER_WORD;
util_bitmask_word mask = 1 << bit;
assert(bm);
if(index < bm->filled) {
assert(bm->words[word] & mask);
return TRUE;
}
if(index >= bm->size)
return FALSE;
if(bm->words[word] & mask) {
util_bitmask_filled_set(bm, index);
return TRUE;
}
else
return FALSE;
}
unsigned
util_bitmask_get_next_index(struct util_bitmask *bm,
unsigned index)
{
unsigned word = index / UTIL_BITMASK_BITS_PER_WORD;
unsigned bit = index % UTIL_BITMASK_BITS_PER_WORD;
util_bitmask_word mask = 1 << bit;
if(index < bm->filled) {
assert(bm->words[word] & mask);
return index;
}
if(index >= bm->size) {
return UTIL_BITMASK_INVALID_INDEX;
}
/* Do a linear search */
while(word < bm->size / UTIL_BITMASK_BITS_PER_WORD) {
while(bit < UTIL_BITMASK_BITS_PER_WORD) {
if(bm->words[word] & mask) {
if(index == bm->filled) {
++bm->filled;
assert(bm->filled <= bm->size);
}
return index;
}
++index;
++bit;
mask <<= 1;
}
++word;
bit = 0;
mask = 1;
}
return UTIL_BITMASK_INVALID_INDEX;
}
unsigned
util_bitmask_get_first_index(struct util_bitmask *bm)
{
return util_bitmask_get_next_index(bm, 0);
}
void
util_bitmask_destroy(struct util_bitmask *bm)
{
if (bm) {
FREE(bm->words);
FREE(bm);
}
}
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