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add io_fd_canwrite (like io_fd but assume the fd is writable)

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save a few syscalls here and there
This commit is contained in:
leitner
2012-04-10 21:15:51 +00:00
parent 6e6fc8b85d
commit e175800a8c
15 changed files with 322 additions and 63 deletions
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31
CAS.h
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@@ -30,19 +30,6 @@ static inline int compare_and_swap(volatile size_t* x,size_t oldval,size_t newva
#endif
}
/* *x += val; */
static inline void atomic_add(size_t* x,size_t val) {
#ifdef USE_BUILTINS
__sync_add_and_fetch(x,val);
#elif defined(__i386__)
asm volatile ("lock; addl %1, %0" : "+m" (*x) : "ir" (val) );
#elif defined(__x86_64__)
asm volatile ("lock; addq %1, %0" : "+m" (*x) : "ir" (val) );
#else
#error architecture not supported and gcc too old, edit CAS.h
#endif
}
/* return *x += val; */
static inline size_t atomic_add_return(size_t* x,size_t val) {
#ifdef USE_BUILTINS
@@ -56,7 +43,23 @@ static inline size_t atomic_add_return(size_t* x,size_t val) {
asm volatile ("lock; xaddq %1, %0" : "+m" (*x), "+r" (val) :: "memory" );
return i + val;
#else
#error architecture not supported and gcc too old, edit CAS.h
size_t y;
for (y=*x; compare_and_swap(&x,y,y+val)==0; y=*x) ;
return y+val;
#endif
}
/* *x += val; */
static inline void atomic_add(size_t* x,size_t val) {
#ifdef USE_BUILTINS
__sync_add_and_fetch(x,val);
#elif defined(__i386__)
asm volatile ("lock; addl %1, %0" : "+m" (*x) : "ir" (val) );
#elif defined(__x86_64__)
asm volatile ("lock; addq %1, %0" : "+m" (*x) : "ir" (val) );
#else
atomic_add_return(&x,val);
#endif
}