106 lines
3.5 KiB
C++
106 lines
3.5 KiB
C++
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/*
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* Copyright 2005-2006 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*
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*/
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inline bool BitMap::par_set_bit(idx_t bit) {
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verify_index(bit);
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volatile idx_t* const addr = word_addr(bit);
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const idx_t mask = bit_mask(bit);
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idx_t old_val = *addr;
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do {
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const idx_t new_val = old_val | mask;
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if (new_val == old_val) {
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return false; // Someone else beat us to it.
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}
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const idx_t cur_val = (idx_t) Atomic::cmpxchg_ptr((void*) new_val,
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(volatile void*) addr,
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(void*) old_val);
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if (cur_val == old_val) {
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return true; // Success.
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}
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old_val = cur_val; // The value changed, try again.
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} while (true);
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}
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inline bool BitMap::par_clear_bit(idx_t bit) {
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verify_index(bit);
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volatile idx_t* const addr = word_addr(bit);
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const idx_t mask = ~bit_mask(bit);
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idx_t old_val = *addr;
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do {
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const idx_t new_val = old_val & mask;
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if (new_val == old_val) {
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return false; // Someone else beat us to it.
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}
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const idx_t cur_val = (idx_t) Atomic::cmpxchg_ptr((void*) new_val,
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(volatile void*) addr,
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(void*) old_val);
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if (cur_val == old_val) {
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return true; // Success.
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}
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old_val = cur_val; // The value changed, try again.
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} while (true);
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}
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inline BitMap::idx_t
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BitMap::find_next_one_bit(idx_t beg_bit, idx_t end_bit) const
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{
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verify_range(beg_bit, end_bit);
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assert(bit_in_word(end_bit) == 0, "end_bit not word-aligned");
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if (beg_bit == end_bit) {
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return beg_bit;
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}
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idx_t index = word_index(beg_bit);
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idx_t r_index = word_index(end_bit);
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idx_t res_bit = beg_bit;
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// check bits including and to the _left_ of offset's position
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idx_t res = map(index) >> bit_in_word(res_bit);
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if (res != (uintptr_t) NoBits) {
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// find the position of the 1-bit
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for (; !(res & 1); res_bit++) {
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res = res >> 1;
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}
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assert(res_bit >= beg_bit && res_bit < end_bit, "just checking");
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return res_bit;
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}
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// skip over all word length 0-bit runs
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for (index++; index < r_index; index++) {
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res = map(index);
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if (res != (uintptr_t) NoBits) {
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// found a 1, return the offset
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for (res_bit = bit_index(index); !(res & 1); res_bit++) {
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res = res >> 1;
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}
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assert(res & 1, "tautology; see loop condition");
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assert(res_bit >= beg_bit && res_bit < end_bit, "just checking");
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return res_bit;
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}
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}
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return end_bit;
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}
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