99 lines
2.0 KiB
C
99 lines
2.0 KiB
C
/*
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* Copyright (c) 2015, Xilinx Inc. and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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/*
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* @file linux/mutex.h
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* @brief Linux mutex primitives for libmetal.
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*/
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#ifndef __METAL_MUTEX__H__
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#error "Include metal/mutex.h instead of metal/linux/mutex.h"
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#endif
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#ifndef __METAL_LINUX_MUTEX__H__
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#define __METAL_LINUX_MUTEX__H__
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#include <unistd.h>
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#include <sys/syscall.h>
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#include <linux/futex.h>
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#include <metal/atomic.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef struct {
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atomic_int v;
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} metal_mutex_t;
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/*
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* METAL_MUTEX_INIT - used for initializing an mutex elmenet in a static struct
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* or global
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*/
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#define METAL_MUTEX_INIT(m) { ATOMIC_VAR_INIT(0) }
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/*
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* METAL_MUTEX_DEFINE - used for defining and initializing a global or
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* static singleton mutex
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*/
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#define METAL_MUTEX_DEFINE(m) metal_mutex_t m = METAL_MUTEX_INIT(m)
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static inline int __metal_mutex_cmpxchg(metal_mutex_t *mutex,
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int exp, int val)
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{
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atomic_compare_exchange_strong(&mutex->v, (int *)&exp, val);
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return exp;
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}
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static inline void __metal_mutex_init(metal_mutex_t *mutex)
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{
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atomic_store(&mutex->v, 0);
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}
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static inline void __metal_mutex_deinit(metal_mutex_t *mutex)
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{
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(void)mutex;
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}
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static inline int __metal_mutex_try_acquire(metal_mutex_t *mutex)
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{
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int val = 0;
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return atomic_compare_exchange_strong(&mutex->v, &val, 1);
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}
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static inline void __metal_mutex_acquire(metal_mutex_t *mutex)
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{
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int c = 0;
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if (atomic_compare_exchange_strong(&mutex->v, &c, 1))
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return;
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if (c != 2)
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c = atomic_exchange(&mutex->v, 2);
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while (c != 0) {
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syscall(SYS_futex, &mutex->v, FUTEX_WAIT, 2, NULL, NULL, 0);
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c = atomic_exchange(&mutex->v, 2);
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}
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}
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static inline void __metal_mutex_release(metal_mutex_t *mutex)
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{
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if (atomic_fetch_sub(&mutex->v, 1) != 1) {
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atomic_store(&mutex->v, 0);
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syscall(SYS_futex, &mutex->v, FUTEX_WAKE, 1, NULL, NULL, 0);
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}
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}
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static inline int __metal_mutex_is_acquired(metal_mutex_t *mutex)
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{
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return atomic_load(&mutex->v);
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* __METAL_LINUX_MUTEX__H__ */
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