1 /* Copyright (c) 2013, Ben Noordhuis <info@bnoordhuis.nl> 2 * 3 * Permission to use, copy, modify, and/or distribute this software for any 4 * purpose with or without fee is hereby granted, provided that the above 5 * copyright notice and this permission notice appear in all copies. 6 * 7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 10 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 12 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 13 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 14 */ 15 16 #ifndef UV_ATOMIC_OPS_H_ 17 #define UV_ATOMIC_OPS_H_ 18 19 #include "internal.h" /* UV_UNUSED */ 20 21 #if defined(__SUNPRO_C) || defined(__SUNPRO_CC) 22 #include <atomic.h> 23 #endif 24 25 UV_UNUSED(static int cmpxchgi(int* ptr, int oldval, int newval)); 26 UV_UNUSED(static void cpu_relax(void)); 27 28 /* Prefer hand-rolled assembly over the gcc builtins because the latter also 29 * issue full memory barriers. 30 */ 31 UV_UNUSED(static int cmpxchgi(int* ptr, int oldval, int newval)) { 32 #if defined(__i386__) || defined(__x86_64__) 33 int out; 34 __asm__ __volatile__ ("lock; cmpxchg %2, %1;" 35 : "=a" (out), "+m" (*(volatile int*) ptr) 36 : "r" (newval), "0" (oldval) 37 : "memory"); 38 return out; 39 #elif defined(__MVS__) 40 unsigned int op4; 41 if (__plo_CSST(ptr, (unsigned int*) &oldval, newval, 42 (unsigned int*) ptr, *ptr, &op4)) 43 return oldval; 44 else 45 return op4; 46 #elif defined(__SUNPRO_C) || defined(__SUNPRO_CC) 47 return atomic_cas_uint((uint_t *)ptr, (uint_t)oldval, (uint_t)newval); 48 #else 49 return __sync_val_compare_and_swap(ptr, oldval, newval); 50 #endif 51 } 52 53 UV_UNUSED(static void cpu_relax(void)) { 54 #if defined(__i386__) || defined(__x86_64__) 55 __asm__ __volatile__ ("rep; nop"); /* a.k.a. PAUSE */ 56 #elif (defined(__arm__) && __ARM_ARCH >= 7) || defined(__aarch64__) 57 __asm__ volatile("yield"); 58 #endif 59 } 60 61 #endif /* UV_ATOMIC_OPS_H_ */ 62