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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "runtime/atomic.inline.hpp"
27
28 /*
29 * This is the default implementation of byte-sized cmpxchg. It emulates jbyte-sized cmpxchg
30 * in terms of jint-sized cmpxchg. Platforms may override this by defining their own inline definition
31 * as well as defining VM_HAS_SPECIALIZED_CMPXCHG_BYTE. This will cause the platform specific
32 * implementation to be used instead.
33 */
34 jbyte Atomic::cmpxchg_general(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) {
35 assert(sizeof(jbyte) == 1, "assumption.");
36 uintptr_t dest_addr = (uintptr_t)dest;
37 uintptr_t offset = dest_addr % sizeof(jint);
38 volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
39 jint cur = *dest_int;
40 jbyte* cur_as_bytes = (jbyte*)(&cur);
41 jint new_val = cur;
42 jbyte* new_val_as_bytes = (jbyte*)(&new_val);
43 new_val_as_bytes[offset] = exchange_value;
44 while (cur_as_bytes[offset] == compare_value) {
45 jint res = cmpxchg(new_val, dest_int, cur);
46 if (res == cur) break;
47 cur = res;
48 new_val = cur;
49 new_val_as_bytes[offset] = exchange_value;
50 }
51 return cur_as_bytes[offset];
52 }
53
54 unsigned Atomic::xchg(unsigned int exchange_value, volatile unsigned int* dest) {
55 assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
56 return (unsigned int)Atomic::xchg((jint)exchange_value, (volatile jint*)dest);
57 }
58
59 unsigned Atomic::cmpxchg(unsigned int exchange_value,
60 volatile unsigned int* dest, unsigned int compare_value) {
61 assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
62 return (unsigned int)Atomic::cmpxchg((jint)exchange_value, (volatile jint*)dest,
63 (jint)compare_value);
64 }
65
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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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "runtime/atomic.inline.hpp"
27
28 /*
29 * This is the default implementation of byte-sized cmpxchg. It emulates jbyte-sized cmpxchg
30 * in terms of jint-sized cmpxchg. Platforms may override this by defining their own inline definition
31 * in their AtomicPlatform class.
32 */
33 jbyte AtomicBase::cmpxchg_general(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) {
34 assert(sizeof(jbyte) == 1, "assumption.");
35 uintptr_t dest_addr = (uintptr_t)dest;
36 uintptr_t offset = dest_addr % sizeof(jint);
37 volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
38 jint cur = *dest_int;
39 jbyte* cur_as_bytes = (jbyte*)(&cur);
40 jint new_val = cur;
41 jbyte* new_val_as_bytes = (jbyte*)(&new_val);
42 new_val_as_bytes[offset] = exchange_value;
43 while (cur_as_bytes[offset] == compare_value) {
44 jint res = Atomic::cmpxchg(new_val, dest_int, cur);
45 if (res == cur) break;
46 cur = res;
47 new_val = cur;
48 new_val_as_bytes[offset] = exchange_value;
49 }
50 return cur_as_bytes[offset];
51 }
52
53 unsigned Atomic::xchg(unsigned int exchange_value, volatile unsigned int* dest) {
54 assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
55 return (unsigned int)Atomic::xchg((jint)exchange_value, (volatile jint*)dest);
56 }
57
58 unsigned Atomic::cmpxchg(unsigned int exchange_value,
59 volatile unsigned int* dest, unsigned int compare_value) {
60 assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
61 return (unsigned int)Atomic::cmpxchg((jint)exchange_value, (volatile jint*)dest,
62 (jint)compare_value);
63 }
64
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