| 1 | |
| 2 | * Generic C implementation of atomic counter operations. Usable on
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| 3 | * UP systems only. Do not include in machine independent code.
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| 4 | *
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| 5 | * Originally implemented for MN10300.
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| 6 | *
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| 7 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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| 8 | * Written by David Howells ([email protected])
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| 9 | *
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| 10 | * This program is free software; you can redistribute it and/or
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| 11 | * modify it under the terms of the GNU General Public Licence
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| 12 | * as published by the Free Software Foundation; either version
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| 13 | * 2 of the Licence, or (at your option) any later version.
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| 14 |
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| 15 | #ifndef __ASM_GENERIC_ATOMIC_H
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| 16 | #define __ASM_GENERIC_ATOMIC_H
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| 17 |
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| 18 | #include <asm/cmpxchg.h>
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| 19 |
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| 20 | #ifdef CONFIG_SMP
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| 21 |
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| 22 | # if !defined(atomic_add_return) || !defined(atomic_sub_return) || \
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| 23 | !defined(atomic_clear_mask) || !defined(atomic_set_mask)
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| 24 | # error "SMP requires a little arch-specific magic"
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| 25 | # endif
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| 26 | #endif
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| 27 |
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| 28 | |
| 29 | * Atomic operations that C can't guarantee us. Useful for
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| 30 | * resource counting etc..
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| 31 |
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| 32 |
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| 33 | #define ATOMIC_INIT(i) { (i) }
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| 34 |
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| 35 | #ifdef __KERNEL__
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| 36 |
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| 37 | |
| 38 | * atomic_read - read atomic variable
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| 39 | * @v: pointer of type atomic_t
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| 40 | *
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| 41 | * Atomically reads the value of @v.
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| 42 |
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| 43 | #ifndef atomic_read
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| 44 | #define atomic_read(v) (*(volatile int *)&(v)->counter)
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| 45 | #endif
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| 46 |
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| 47 | |
| 48 | * atomic_set - set atomic variable
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| 49 | * @v: pointer of type atomic_t
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| 50 | * @i: required value
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| 51 | *
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| 52 | * Atomically sets the value of @v to @i.
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| 53 |
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| 54 | #define atomic_set(v, i) (((v)->counter) = (i))
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| 55 |
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| 56 | #include <linux/irqflags.h>
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| 57 |
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| 58 | |
| 59 | * atomic_add_return - add integer to atomic variable
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| 60 | * @i: integer value to add
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| 61 | * @v: pointer of type atomic_t
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| 62 | *
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| 63 | * Atomically adds @i to @v and returns the result
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| 64 |
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| 65 | #ifndef atomic_add_return
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| 66 | static inline int atomic_add_return(int i, atomic_t *v)
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| 67 | {
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| 68 | unsigned long flags;
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| 69 | int temp;
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| 70 |
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| 71 | raw_local_irq_save(flags);
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| 72 | temp = v->counter;
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| 73 | temp += i;
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| 74 | v->counter = temp;
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| 75 | raw_local_irq_restore(flags);
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| 76 |
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| 77 | return temp;
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| 78 | }
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| 79 | #endif
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| 80 |
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| 81 | |
| 82 | * atomic_sub_return - subtract integer from atomic variable
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| 83 | * @i: integer value to subtract
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| 84 | * @v: pointer of type atomic_t
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| 85 | *
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| 86 | * Atomically subtracts @i from @v and returns the result
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| 87 |
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| 88 | #ifndef atomic_sub_return
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| 89 | static inline int atomic_sub_return(int i, atomic_t *v)
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| 90 | {
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| 91 | unsigned long flags;
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| 92 | int temp;
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| 93 |
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| 94 | raw_local_irq_save(flags);
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| 95 | temp = v->counter;
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| 96 | temp -= i;
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| 97 | v->counter = temp;
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| 98 | raw_local_irq_restore(flags);
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| 99 |
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| 100 | return temp;
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| 101 | }
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| 102 | #endif
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| 103 |
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| 104 | static inline int atomic_add_negative(int i, atomic_t *v)
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| 105 | {
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| 106 | return atomic_add_return(i, v) < 0;
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| 107 | }
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| 108 |
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| 109 | static inline void atomic_add(int i, atomic_t *v)
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| 110 | {
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| 111 | atomic_add_return(i, v);
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| 112 | }
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| 113 |
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| 114 | static inline void atomic_sub(int i, atomic_t *v)
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| 115 | {
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| 116 | atomic_sub_return(i, v);
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| 117 | }
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| 118 |
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| 119 | static inline void atomic_inc(atomic_t *v)
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| 120 | {
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| 121 | atomic_add_return(1, v);
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| 122 | }
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| 123 |
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| 124 | static inline void atomic_dec(atomic_t *v)
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| 125 | {
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| 126 | atomic_sub_return(1, v);
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| 127 | }
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| 128 |
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| 129 | #define atomic_dec_return(v) atomic_sub_return(1, (v))
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| 130 | #define atomic_inc_return(v) atomic_add_return(1, (v))
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| 131 |
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| 132 | #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
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| 133 | #define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
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| 134 | #define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
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| 135 |
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| 136 | #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
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| 137 | #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
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| 138 |
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| 139 | static inline int __atomic_add_unless(atomic_t *v, int a, int u)
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| 140 | {
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| 141 | int c, old;
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| 142 | c = atomic_read(v);
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| 143 | while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
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| 144 | c = old;
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| 145 | return c;
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| 146 | }
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| 147 |
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| 148 | |
| 149 | * atomic_clear_mask - Atomically clear bits in atomic variable
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| 150 | * @mask: Mask of the bits to be cleared
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| 151 | * @v: pointer of type atomic_t
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| 152 | *
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| 153 | * Atomically clears the bits set in @mask from @v
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| 154 |
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| 155 | #ifndef atomic_clear_mask
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| 156 | static inline void atomic_clear_mask(unsigned long mask, atomic_t *v)
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| 157 | {
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| 158 | unsigned long flags;
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| 159 |
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| 160 | mask = ~mask;
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| 161 | raw_local_irq_save(flags);
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| 162 | v->counter &= mask;
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| 163 | raw_local_irq_restore(flags);
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| 164 | }
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| 165 | #endif
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| 166 |
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| 167 | |
| 168 | * atomic_set_mask - Atomically set bits in atomic variable
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| 169 | * @mask: Mask of the bits to be set
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| 170 | * @v: pointer of type atomic_t
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| 171 | *
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| 172 | * Atomically sets the bits set in @mask in @v
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| 173 |
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| 174 | #ifndef atomic_set_mask
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| 175 | static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
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| 176 | {
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| 177 | unsigned long flags;
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| 178 |
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| 179 | raw_local_irq_save(flags);
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| 180 | v->counter |= mask;
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| 181 | raw_local_irq_restore(flags);
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| 182 | }
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| 183 | #endif
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| 184 |
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| 185 |
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| 186 | #define smp_mb__before_atomic_dec() barrier()
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| 187 | #define smp_mb__after_atomic_dec() barrier()
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| 188 | #define smp_mb__before_atomic_inc() barrier()
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| 189 | #define smp_mb__after_atomic_inc() barrier()
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| 190 |
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| 191 | #endif
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| 192 | #endif
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