1 #ifndef _TOOLS_LINUX_ASM_X86_ATOMIC_H 2 #define _TOOLS_LINUX_ASM_X86_ATOMIC_H 3 4 #include <linux/compiler.h> 5 #include <linux/types.h> 6 #include "rmwcc.h" 7 8 #define LOCK_PREFIX "\n\tlock; " 9 10 /* 11 * Atomic operations that C can't guarantee us. Useful for 12 * resource counting etc.. 13 */ 14 15 #define ATOMIC_INIT(i) { (i) } 16 17 /** 18 * atomic_read - read atomic variable 19 * @v: pointer of type atomic_t 20 * 21 * Atomically reads the value of @v. 22 */ 23 static inline int atomic_read(const atomic_t *v) 24 { 25 return ACCESS_ONCE((v)->counter); 26 } 27 28 /** 29 * atomic_set - set atomic variable 30 * @v: pointer of type atomic_t 31 * @i: required value 32 * 33 * Atomically sets the value of @v to @i. 34 */ 35 static inline void atomic_set(atomic_t *v, int i) 36 { 37 v->counter = i; 38 } 39 40 /** 41 * atomic_inc - increment atomic variable 42 * @v: pointer of type atomic_t 43 * 44 * Atomically increments @v by 1. 45 */ 46 static inline void atomic_inc(atomic_t *v) 47 { 48 asm volatile(LOCK_PREFIX "incl %0" 49 : "+m" (v->counter)); 50 } 51 52 /** 53 * atomic_dec_and_test - decrement and test 54 * @v: pointer of type atomic_t 55 * 56 * Atomically decrements @v by 1 and 57 * returns true if the result is 0, or false for all other 58 * cases. 59 */ 60 static inline int atomic_dec_and_test(atomic_t *v) 61 { 62 GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e"); 63 } 64 65 #endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */ 66