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