| 1 |
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| 2 | |
| 3 | *
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| 4 | * Copyright © International Business Machines Corp., 2009
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| 5 | *
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| 6 | * DESCRIPTION
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| 7 | * GCC atomic builtin wrappers
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| 8 | * http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
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| 9 | *
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| 10 | * AUTHOR
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| 11 | * Darren Hart <[email protected]>
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| 12 | *
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| 13 | * HISTORY
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| 14 | * 2009-Nov-17: Initial version by Darren Hart <[email protected]>
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| 15 | *
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| 16 | ****************************************************************************
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| 17 |
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| 18 | #ifndef _ATOMIC_H
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| 19 | #define _ATOMIC_H
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| 20 |
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| 21 | typedef struct {
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| 22 | volatile int val;
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| 23 | } atomic_t;
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| 24 |
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| 25 | #define ATOMIC_INITIALIZER { 0 }
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| 26 |
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| 27 | |
| 28 | * atomic_cmpxchg() - Atomic compare and exchange
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| 29 | * @uaddr: The address of the futex to be modified
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| 30 | * @oldval: The expected value of the futex
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| 31 | * @newval: The new value to try and assign the futex
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| 32 | *
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| 33 | * Return the old value of addr->val.
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| 34 |
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| 35 | static inline int
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| 36 | atomic_cmpxchg(atomic_t *addr, int oldval, int newval)
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| 37 | {
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| 38 | return __sync_val_compare_and_swap(&addr->val, oldval, newval);
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| 39 | }
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| 40 |
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| 41 | |
| 42 | * atomic_inc() - Atomic incrememnt
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| 43 | * @addr: Address of the variable to increment
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| 44 | *
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| 45 | * Return the new value of addr->val.
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| 46 |
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| 47 | static inline int
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| 48 | atomic_inc(atomic_t *addr)
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| 49 | {
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| 50 | return __sync_add_and_fetch(&addr->val, 1);
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| 51 | }
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| 52 |
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| 53 | |
| 54 | * atomic_dec() - Atomic decrement
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| 55 | * @addr: Address of the variable to decrement
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| 56 | *
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| 57 | * Return the new value of addr-val.
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| 58 |
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| 59 | static inline int
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| 60 | atomic_dec(atomic_t *addr)
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| 61 | {
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| 62 | return __sync_sub_and_fetch(&addr->val, 1);
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| 63 | }
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| 64 |
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| 65 | |
| 66 | * atomic_set() - Atomic set
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| 67 | * @addr: Address of the variable to set
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| 68 | * @newval: New value for the atomic_t
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| 69 | *
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| 70 | * Return the new value of addr->val.
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| 71 |
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| 72 | static inline int
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| 73 | atomic_set(atomic_t *addr, int newval)
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| 74 | {
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| 75 | addr->val = newval;
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| 76 | return newval;
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| 77 | }
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| 78 |
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| 79 | #endif
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