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src/share/vm/utilities/bitMap.inline.hpp@a61af66fc99e (annotated)

src/share/vm/utilities/bitMap.inline.hpp

Sat, 01 Dec 2007 00:00:00 +0000

author

duke

date

Sat, 01 Dec 2007 00:00:00 +0000

changeset 435

a61af66fc99e

child 777

37f87013dfd8

permissions

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duke@435	1	/*
duke@435	2	* Copyright 2005-2006 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	inline bool BitMap::par_set_bit(idx_t bit) {
duke@435	26	verify_index(bit);
duke@435	27	volatile idx_t* const addr = word_addr(bit);
duke@435	28	const idx_t mask = bit_mask(bit);
duke@435	29	idx_t old_val = *addr;
duke@435	30
duke@435	31	do {
duke@435	32	const idx_t new_val = old_val | mask;
duke@435	33	if (new_val == old_val) {
duke@435	34	return false; // Someone else beat us to it.
duke@435	35	}
duke@435	36	const idx_t cur_val = (idx_t) Atomic::cmpxchg_ptr((void*) new_val,
duke@435	37	(volatile void*) addr,
duke@435	38	(void*) old_val);
duke@435	39	if (cur_val == old_val) {
duke@435	40	return true; // Success.
duke@435	41	}
duke@435	42	old_val = cur_val; // The value changed, try again.
duke@435	43	} while (true);
duke@435	44	}
duke@435	45
duke@435	46	inline bool BitMap::par_clear_bit(idx_t bit) {
duke@435	47	verify_index(bit);
duke@435	48	volatile idx_t* const addr = word_addr(bit);
duke@435	49	const idx_t mask = ~bit_mask(bit);
duke@435	50	idx_t old_val = *addr;
duke@435	51
duke@435	52	do {
duke@435	53	const idx_t new_val = old_val & mask;
duke@435	54	if (new_val == old_val) {
duke@435	55	return false; // Someone else beat us to it.
duke@435	56	}
duke@435	57	const idx_t cur_val = (idx_t) Atomic::cmpxchg_ptr((void*) new_val,
duke@435	58	(volatile void*) addr,
duke@435	59	(void*) old_val);
duke@435	60	if (cur_val == old_val) {
duke@435	61	return true; // Success.
duke@435	62	}
duke@435	63	old_val = cur_val; // The value changed, try again.
duke@435	64	} while (true);
duke@435	65	}
duke@435	66
duke@435	67	inline BitMap::idx_t
duke@435	68	BitMap::find_next_one_bit(idx_t beg_bit, idx_t end_bit) const
duke@435	69	{
duke@435	70	verify_range(beg_bit, end_bit);
duke@435	71	assert(bit_in_word(end_bit) == 0, "end_bit not word-aligned");
duke@435	72
duke@435	73	if (beg_bit == end_bit) {
duke@435	74	return beg_bit;
duke@435	75	}
duke@435	76
duke@435	77	idx_t index = word_index(beg_bit);
duke@435	78	idx_t r_index = word_index(end_bit);
duke@435	79	idx_t res_bit = beg_bit;
duke@435	80
duke@435	81	// check bits including and to the _left_ of offset's position
duke@435	82	idx_t res = map(index) >> bit_in_word(res_bit);
duke@435	83	if (res != (uintptr_t) NoBits) {
duke@435	84	// find the position of the 1-bit
duke@435	85	for (; !(res & 1); res_bit++) {
duke@435	86	res = res >> 1;
duke@435	87	}
duke@435	88	assert(res_bit >= beg_bit && res_bit < end_bit, "just checking");
duke@435	89	return res_bit;
duke@435	90	}
duke@435	91	// skip over all word length 0-bit runs
duke@435	92	for (index++; index < r_index; index++) {
duke@435	93	res = map(index);
duke@435	94	if (res != (uintptr_t) NoBits) {
duke@435	95	// found a 1, return the offset
duke@435	96	for (res_bit = bit_index(index); !(res & 1); res_bit++) {
duke@435	97	res = res >> 1;
duke@435	98	}
duke@435	99	assert(res & 1, "tautology; see loop condition");
duke@435	100	assert(res_bit >= beg_bit && res_bit < end_bit, "just checking");
duke@435	101	return res_bit;
duke@435	102	}
duke@435	103	}
duke@435	104	return end_bit;
duke@435	105	}