comparison src/share/vm/utilities/bitMap.inline.hpp @ 0:a61af66fc99e

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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children 37f87013dfd8
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-1:000000000000 0:9023f046c892
1 /*
2 * Copyright 2005-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 inline bool BitMap::par_set_bit(idx_t bit) {
26 verify_index(bit);
27 volatile idx_t* const addr = word_addr(bit);
28 const idx_t mask = bit_mask(bit);
29 idx_t old_val = *addr;
30
31 do {
32 const idx_t new_val = old_val | mask;
33 if (new_val == old_val) {
34 return false; // Someone else beat us to it.
35 }
36 const idx_t cur_val = (idx_t) Atomic::cmpxchg_ptr((void*) new_val,
37 (volatile void*) addr,
38 (void*) old_val);
39 if (cur_val == old_val) {
40 return true; // Success.
41 }
42 old_val = cur_val; // The value changed, try again.
43 } while (true);
44 }
45
46 inline bool BitMap::par_clear_bit(idx_t bit) {
47 verify_index(bit);
48 volatile idx_t* const addr = word_addr(bit);
49 const idx_t mask = ~bit_mask(bit);
50 idx_t old_val = *addr;
51
52 do {
53 const idx_t new_val = old_val & mask;
54 if (new_val == old_val) {
55 return false; // Someone else beat us to it.
56 }
57 const idx_t cur_val = (idx_t) Atomic::cmpxchg_ptr((void*) new_val,
58 (volatile void*) addr,
59 (void*) old_val);
60 if (cur_val == old_val) {
61 return true; // Success.
62 }
63 old_val = cur_val; // The value changed, try again.
64 } while (true);
65 }
66
67 inline BitMap::idx_t
68 BitMap::find_next_one_bit(idx_t beg_bit, idx_t end_bit) const
69 {
70 verify_range(beg_bit, end_bit);
71 assert(bit_in_word(end_bit) == 0, "end_bit not word-aligned");
72
73 if (beg_bit == end_bit) {
74 return beg_bit;
75 }
76
77 idx_t index = word_index(beg_bit);
78 idx_t r_index = word_index(end_bit);
79 idx_t res_bit = beg_bit;
80
81 // check bits including and to the _left_ of offset's position
82 idx_t res = map(index) >> bit_in_word(res_bit);
83 if (res != (uintptr_t) NoBits) {
84 // find the position of the 1-bit
85 for (; !(res & 1); res_bit++) {
86 res = res >> 1;
87 }
88 assert(res_bit >= beg_bit && res_bit < end_bit, "just checking");
89 return res_bit;
90 }
91 // skip over all word length 0-bit runs
92 for (index++; index < r_index; index++) {
93 res = map(index);
94 if (res != (uintptr_t) NoBits) {
95 // found a 1, return the offset
96 for (res_bit = bit_index(index); !(res & 1); res_bit++) {
97 res = res >> 1;
98 }
99 assert(res & 1, "tautology; see loop condition");
100 assert(res_bit >= beg_bit && res_bit < end_bit, "just checking");
101 return res_bit;
102 }
103 }
104 return end_bit;
105 }