232 lines
5.1 KiB
C
232 lines
5.1 KiB
C
/* Massimo:
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* This is a slightly modified version of the linux kernel file
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* /<source-dir>/include/asm-x86/atomic_64.h
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*
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*/
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#ifndef FF_ARCH_X86_64_ATOMIC_H
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#define FF_ARCH_X86_64_ATOMIC_H
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/* atomic_t should be 32 bit signed type */
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#if !defined(likely)
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#define likely(x) __builtin_expect(!!(x), 1)
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#endif
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#if !defined(unlikely)
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#define unlikely(x) __builtin_expect(!!(x), 0)
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#endif
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/*
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* Atomic operations that C can't guarantee us. Useful for
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* resource counting etc..
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*/
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#define LOCK_PREFIX "lock ; "
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/*
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* Make sure gcc doesn't try to be clever and move things around
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* on us. We need to use _exactly_ the address the user gave us,
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* not some alias that contains the same information.
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*/
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typedef struct { volatile unsigned long counter; } atomic_t;
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#define ATOMIC_INIT(i) { (i) }
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/**
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* atomic_read - read atomic variable
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* @v: pointer of type atomic_t
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*
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* Atomically reads the value of @v.
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*/
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#define atomic_read(v) ((v)->counter)
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/**
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* atomic_set - set atomic variable
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* @v: pointer of type atomic_t
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* @i: required value
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*
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* Atomically sets the value of @v to @i.
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*/
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#define atomic_set(v,i) (((v)->counter) = (i))
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/**
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* atomic_inc - increment atomic variable
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* @v: pointer of type atomic_t
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*
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* Atomically increments @v by 1.
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*/
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static __inline__ void atomic_inc(atomic_t *v)
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{
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__asm__ __volatile__(
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LOCK_PREFIX "incl %0"
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:"=m" (v->counter)
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:"m" (v->counter));
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}
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/**
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* atomic64_dec - decrement atomic64 variable
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* @v: pointer to type atomic64_t
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*
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* Atomically decrements @v by 1.
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*/
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static __inline__ void atomic_dec(atomic_t *v)
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{
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__asm__ __volatile__(
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LOCK_PREFIX "decq %0"
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: "=m" (v->counter)
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: "m" (v->counter));
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}
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/* An 64bit atomic type */
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typedef struct { volatile unsigned long counter; } atomic64_t;
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#define ATOMIC64_INIT(i) { (i) }
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/**
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* atomic64_read - read atomic64 variable
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* @v: pointer of type atomic64_t
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*
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* Atomically reads the value of @v.
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* Doesn't imply a read memory barrier.
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*/
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#define atomic64_read(v) ((v)->counter)
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/**
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* atomic64_set - set atomic64 variable
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* @v: pointer to type atomic64_t
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* @i: required value
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*
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* Atomically sets the value of @v to @i.
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*/
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#define atomic64_set(v,i) (((v)->counter) = (i))
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/**
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* atomic64_inc - increment atomic64 variable
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* @v: pointer to type atomic64_t
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*
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* Atomically increments @v by 1.
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*/
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static __inline__ void atomic64_inc(atomic64_t *v)
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{
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__asm__ __volatile__(
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LOCK_PREFIX "incq %0"
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:"=m" (v->counter)
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:"m" (v->counter));
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}
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#define atomic64_inc_return(v) (atomic64_add_return(1, (v)))
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#define atomic64_dec_return(v) (atomic64_sub_return(1, (v)))
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/**
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* atomic64_dec - decrement atomic64 variable
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* @v: pointer to type atomic64_t
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*
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* Atomically decrements @v by 1.
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*/
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static __inline__ void atomic64_dec(atomic64_t *v)
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{
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__asm__ __volatile__(
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LOCK_PREFIX "decq %0"
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: "=m" (v->counter)
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: "m" (v->counter));
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}
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static __inline__ void atomic64_add(unsigned long i, atomic64_t *v)
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{
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__asm__ __volatile__(
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LOCK_PREFIX "addq %1,%0"
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: "=m" (v->counter)
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: "ir" (i), "m" (v->counter));
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}
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/**
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* atomic64_add_return - add and return
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* @i: integer value to add
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* @v: pointer to type atomic64_t
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*
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* Atomically adds @i to @v and returns @i + @v
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*/
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static __inline__ unsigned long atomic64_add_return(unsigned long i, atomic64_t *v)
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{
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unsigned long __i = i;
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asm volatile(LOCK_PREFIX "xaddq %0, %1;"
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: "+r" (i), "+m" (v->counter)
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: : "memory");
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return i + __i;
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}
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static __inline__ unsigned long atomic64_sub_return(unsigned long i, atomic64_t *v)
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{
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return atomic64_add_return(-i, v);
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}
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/**
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* atomic64_sub - subtract the atomic64 variable
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* @i: integer value to subtract
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* @v: pointer to type atomic64_t
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*
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* Atomically subtracts @i from @v.
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*/
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static __inline__ void atomic64_sub(unsigned long i, atomic64_t *v)
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{
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__asm__ __volatile__(
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LOCK_PREFIX "subq %1,%0"
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: "=m" (v->counter)
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: "ir" (i), "m" (v->counter));
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}
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#define atomic64_cmpxchg(v, old, New) (cmpxchg8(&((v)->counter), (old), (New)))
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/*
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* Atomic compare and exchange. Compare OLD with MEM, if identical,
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* store NEW in MEM. Return the initial value in MEM. Success is
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* indicated by comparing RETURN with OLD.
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*/
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#define __xg(x) ((volatile unsigned long *)(x))
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static __inline__ unsigned long cmpxchg8(volatile void *ptr, unsigned long old,
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unsigned long New)
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{
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unsigned long prev;
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asm volatile(LOCK_PREFIX "cmpxchgq %1,%2"
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: "=a"(prev)
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: "r"(New), "m"(*__xg(ptr)), "0"(old)
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: "memory");
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return prev;
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}
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/**
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* atomic64_add_unless - add unless the number is a given value
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* @v: pointer of type atomic64_t
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* @a: the amount to add to v...
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* @u: ...unless v is equal to u.
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*
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* Atomically adds @a to @v, so unsigned long as it was not @u.
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* Returns non-zero if @v was not @u, and zero otherwise.
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*/
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static inline unsigned long atomic64_add_unless(atomic64_t *v, unsigned long a, unsigned long u)
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{
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unsigned long c, old;
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c = atomic64_read(v);
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for (;;) {
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if (unlikely(c == (u)))
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break;
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old = atomic64_cmpxchg((v), c, c + (a));
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if (likely(old == c))
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break;
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c = old;
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}
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return c != (u);
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}
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#endif /* FF_ARCH_X86_64_ATOMIC_H */
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