1 /* 2 * Copyright (c) 2020 François Tigeot <ftigeot@wolfpond.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #ifndef _ASM_CMPXCHG_H_ 28 #define _ASM_CMPXCHG_H_ 29 30 #define xchg(ptr, value) \ 31 ({ \ 32 __typeof(value) __ret = (value); \ 33 \ 34 switch (sizeof(value)) { \ 35 case 8: \ 36 __asm __volatile("xchgq %0, %1" \ 37 : "+r" (__ret), "+m" (*(ptr)) \ 38 : : "memory"); \ 39 break; \ 40 case 4: \ 41 __asm __volatile("xchgl %0, %1" \ 42 : "+r" (__ret), "+m" (*(ptr)) \ 43 : : "memory"); \ 44 break; \ 45 case 2: \ 46 __asm __volatile("xchgw %0, %1" \ 47 : "+r" (__ret), "+m" (*(ptr)) \ 48 : : "memory"); \ 49 break; \ 50 case 1: \ 51 __asm __volatile("xchgb %0, %1" \ 52 : "+r" (__ret), "+m" (*(ptr)) \ 53 : : "memory"); \ 54 break; \ 55 default: \ 56 panic("xchg(): invalid size %ld\n", sizeof(value)); \ 57 } \ 58 \ 59 __ret; \ 60 }) 61 62 #endif /* _ASM_CMPXCHG_H_ */ 63