1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 #include "nge.h" 30 31 /* 32 * Atomically decrement a counter, but only if it will remain 33 * positive (>=0) afterwards. 34 */ 35 boolean_t 36 nge_atomic_decrease(uint64_t *count_p, uint64_t n) 37 { 38 uint64_t oldval; 39 uint64_t newval; 40 41 /* ATOMICALLY */ 42 do { 43 oldval = *count_p; 44 newval = oldval - n; 45 if (oldval < n) 46 return (B_FALSE); 47 } while (cas64(count_p, oldval, newval) != oldval); 48 49 return (B_TRUE); 50 } 51 52 /* 53 * Atomically increment a counter 54 */ 55 void 56 nge_atomic_increase(uint64_t *count_p, uint64_t n) 57 { 58 uint64_t oldval; 59 uint64_t newval; 60 61 /* ATOMICALLY */ 62 do { 63 oldval = *count_p; 64 newval = oldval + n; 65 } while (cas64(count_p, oldval, newval) != oldval); 66 } 67 68 69 /* 70 * Atomically shift a 32-bit word left, returning 71 * the value it had *before* the shift was applied 72 */ 73 uint32_t 74 nge_atomic_shl32(uint32_t *sp, uint_t count) 75 { 76 uint32_t oldval; 77 uint32_t newval; 78 79 /* ATOMICALLY */ 80 do { 81 oldval = *sp; 82 newval = oldval << count; 83 } while (cas32(sp, oldval, newval) != oldval); 84 85 return (oldval); 86 } 87