24ca0fbb76
The builtin functions __atomic_compare_exchange_* are missing when CONFIG_ATOMIC_OPERATIONS_C is set. Add them and verify they build/work as expected. Signed-off-by: Yuval Peress <peress@google.com>
52 lines
2.5 KiB
C
52 lines
2.5 KiB
C
/*
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* Copyright (c) 2025 Google LLC
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* @file
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* @brief C-based implementation of GCC __atomic built-ins.
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*
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* This file provides a fallback implementation for the C++ atomic functions
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* required by the compiler on architectures that do not have native atomic
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* instructions and are using the generic C implementation of atomics.
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* All operations are made atomic by using a global interrupt lock.
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*/
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#include <zephyr/kernel.h>
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#include <stdint.h>
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/*
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* Note on memory ordering:
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* The `memorder` parameters are ignored because the irq_lock() provides
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* a full memory barrier, which is equivalent to the strongest memory order,
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* __ATOMIC_SEQ_CST. This is always safe.
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*/
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/* === compare_exchange ======================================================= */
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#define DEFINE_ATOMIC_COMPARE_EXCHANGE(n, type) \
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bool __atomic_compare_exchange_##n(volatile void *ptr, void *expected, type desired, \
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bool weak, int success, int failure) \
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{ \
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bool ret = false; \
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unsigned int key = irq_lock(); \
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volatile type *p = ptr; \
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type *e = expected; \
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\
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if (*p == *e) { \
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*p = desired; \
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ret = true; \
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} else { \
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*e = *p; \
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ret = false; \
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} \
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irq_unlock(key); \
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return ret; \
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}
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DEFINE_ATOMIC_COMPARE_EXCHANGE(1, uint8_t)
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DEFINE_ATOMIC_COMPARE_EXCHANGE(2, uint16_t)
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DEFINE_ATOMIC_COMPARE_EXCHANGE(4, uint32_t)
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