9504034733
Obviously, everyone knows that there are 8 bits per byte, so there isn't a lot of magic happening, per se, but it's also helpful to clearly denote where the magic number 8 is referring to the number of bits in a byte. Occasionally, 8 will refer to a field size or offset in a structure, MMR, or word. Occasionally, the number 8 will refer to the number of bytes in a 64-bit value (which should probably be replaced with `sizeof(uint64_t)`). For converting bits to bytes, or vice-versa, let's use `BITS_PER_BYTE` for clarity (or other appropriate `BITS_PER_*` macros). Signed-off-by: Chris Friedt <cfriedt@tenstorrent.com>
481 lines
12 KiB
C
481 lines
12 KiB
C
/*
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* Copyright (c) 1997-2015, Wind River Systems, Inc.
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* Copyright (c) 2021 Intel Corporation
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* Copyright (c) 2023 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef ZEPHYR_INCLUDE_SYS_ATOMIC_H_
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#define ZEPHYR_INCLUDE_SYS_ATOMIC_H_
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#include <stdbool.h>
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#include <zephyr/toolchain.h>
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#include <stddef.h>
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#include <zephyr/sys/atomic_types.h> /* IWYU pragma: export */
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#include <zephyr/types.h>
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#include <zephyr/sys/util.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Low-level primitives come in several styles: */
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#if defined(CONFIG_ATOMIC_OPERATIONS_C)
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/* Generic-but-slow implementation based on kernel locking and syscalls */
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#include <zephyr/sys/atomic_c.h>
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#elif defined(CONFIG_ATOMIC_OPERATIONS_ARCH)
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/* Some architectures need their own implementation */
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# ifdef CONFIG_XTENSA
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/* Not all Xtensa toolchains support GCC-style atomic intrinsics */
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# include <zephyr/arch/xtensa/atomic_xtensa.h>
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# else
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/* Other arch specific implementation */
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# include <zephyr/sys/atomic_arch.h>
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# endif /* CONFIG_XTENSA */
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#else
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/* Default. See this file for the Doxygen reference: */
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#include <zephyr/sys/atomic_builtin.h>
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#endif
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/* Portable higher-level utilities: */
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/**
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* @defgroup atomic_apis Atomic Services APIs
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* @ingroup kernel_apis
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* @{
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*/
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/**
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* @brief Initialize an atomic variable.
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*
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* This macro can be used to initialize an atomic variable. For example,
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* @code atomic_t my_var = ATOMIC_INIT(75); @endcode
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*
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* @param i Value to assign to atomic variable.
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*/
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#define ATOMIC_INIT(i) (i)
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/**
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* @brief Initialize an atomic pointer variable.
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*
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* This macro can be used to initialize an atomic pointer variable. For
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* example,
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* @code atomic_ptr_t my_ptr = ATOMIC_PTR_INIT(&data); @endcode
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*
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* @param p Pointer value to assign to atomic pointer variable.
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*/
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#define ATOMIC_PTR_INIT(p) (p)
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/**
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* @cond INTERNAL_HIDDEN
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*/
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#define ATOMIC_BITS (sizeof(atomic_val_t) * BITS_PER_BYTE)
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#define ATOMIC_MASK(bit) BIT((unsigned long)(bit) & (ATOMIC_BITS - 1U))
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#define ATOMIC_ELEM(addr, bit) ((addr) + ((bit) / ATOMIC_BITS))
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/**
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* INTERNAL_HIDDEN @endcond
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*/
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/**
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* @brief This macro computes the number of atomic variables necessary to
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* represent a bitmap with @a num_bits.
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*
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* @param num_bits Number of bits.
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*/
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#define ATOMIC_BITMAP_SIZE(num_bits) (ROUND_UP(num_bits, ATOMIC_BITS) / ATOMIC_BITS)
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/**
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* @brief Define an array of atomic variables.
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*
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* This macro defines an array of atomic variables containing at least
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* @a num_bits bits.
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*
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* @note
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* If used from file scope, the bits of the array are initialized to zero;
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* if used from within a function, the bits are left uninitialized.
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*
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* @cond INTERNAL_HIDDEN
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* @note
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* This macro should be replicated in the PREDEFINED field of the documentation
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* Doxyfile.
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* @endcond
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*
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* @param name Name of array of atomic variables.
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* @param num_bits Number of bits needed.
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*/
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#define ATOMIC_DEFINE(name, num_bits) \
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atomic_t name[ATOMIC_BITMAP_SIZE(num_bits)]
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/**
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* @brief Atomically get and test a bit.
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*
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* Atomically get a value and then test whether bit number @a bit of @a target is set or not.
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* The target may be a single atomic variable or an array of them.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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*
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* @return true if the bit was set, false if it wasn't.
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*/
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static inline bool atomic_test_bit(const atomic_t *target, int bit)
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{
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atomic_val_t val = atomic_get(ATOMIC_ELEM(target, bit));
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return (1 & (val >> (bit & (ATOMIC_BITS - 1)))) != 0;
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}
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/**
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* @brief Atomically clear a bit and test it.
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*
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* Atomically clear bit number @a bit of @a target and return its old value.
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* The target may be a single atomic variable or an array of them.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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*
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* @return false if the bit was already cleared, true if it wasn't.
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*/
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static inline bool atomic_test_and_clear_bit(atomic_t *target, int bit)
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{
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atomic_val_t mask = ATOMIC_MASK(bit);
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atomic_val_t old;
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old = atomic_and(ATOMIC_ELEM(target, bit), ~mask);
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return (old & mask) != 0;
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}
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/**
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* @brief Atomically set a bit and test it.
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*
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* Atomically set bit number @a bit of @a target and return its old value.
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* The target may be a single atomic variable or an array of them.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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*
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* @return true if the bit was already set, false if it wasn't.
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*/
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static inline bool atomic_test_and_set_bit(atomic_t *target, int bit)
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{
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atomic_val_t mask = ATOMIC_MASK(bit);
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atomic_val_t old;
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old = atomic_or(ATOMIC_ELEM(target, bit), mask);
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return (old & mask) != 0;
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}
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/**
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* @brief Atomically clear a bit.
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*
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* Atomically clear bit number @a bit of @a target.
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* The target may be a single atomic variable or an array of them.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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*/
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static inline void atomic_clear_bit(atomic_t *target, int bit)
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{
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atomic_val_t mask = ATOMIC_MASK(bit);
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(void)atomic_and(ATOMIC_ELEM(target, bit), ~mask);
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}
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/**
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* @brief Atomically set a bit.
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*
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* Atomically set bit number @a bit of @a target.
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* The target may be a single atomic variable or an array of them.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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*/
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static inline void atomic_set_bit(atomic_t *target, int bit)
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{
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atomic_val_t mask = ATOMIC_MASK(bit);
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(void)atomic_or(ATOMIC_ELEM(target, bit), mask);
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}
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/**
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* @brief Atomically set a bit to a given value.
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*
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* Atomically set bit number @a bit of @a target to value @a val.
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* The target may be a single atomic variable or an array of them.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable or array.
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* @param bit Bit number (starting from 0).
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* @param val true for 1, false for 0.
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*/
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static inline void atomic_set_bit_to(atomic_t *target, int bit, bool val)
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{
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atomic_val_t mask = ATOMIC_MASK(bit);
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if (val) {
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(void)atomic_or(ATOMIC_ELEM(target, bit), mask);
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} else {
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(void)atomic_and(ATOMIC_ELEM(target, bit), ~mask);
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}
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}
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/**
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* @brief Atomic compare-and-set.
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*
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* This routine performs an atomic compare-and-set on @a target. If the current
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* value of @a target equals @a old_value, @a target is set to @a new_value.
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* If the current value of @a target does not equal @a old_value, @a target
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* is left unchanged.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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* @param old_value Original value to compare against.
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* @param new_value New value to store.
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* @return true if @a new_value is written, false otherwise.
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*/
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bool atomic_cas(atomic_t *target, atomic_val_t old_value, atomic_val_t new_value);
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/**
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* @brief Atomic compare-and-set with pointer values
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*
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* This routine performs an atomic compare-and-set on @a target. If the current
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* value of @a target equals @a old_value, @a target is set to @a new_value.
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* If the current value of @a target does not equal @a old_value, @a target
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* is left unchanged.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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* @param old_value Original value to compare against.
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* @param new_value New value to store.
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* @return true if @a new_value is written, false otherwise.
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*/
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bool atomic_ptr_cas(atomic_ptr_t *target, atomic_ptr_val_t old_value,
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atomic_ptr_val_t new_value);
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/**
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* @brief Atomic addition.
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*
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* This routine performs an atomic addition on @a target.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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* @param value Value to add.
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*
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* @return Previous value of @a target.
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*/
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atomic_val_t atomic_add(atomic_t *target, atomic_val_t value);
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/**
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* @brief Atomic subtraction.
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*
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* This routine performs an atomic subtraction on @a target.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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* @param value Value to subtract.
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*
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* @return Previous value of @a target.
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*/
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atomic_val_t atomic_sub(atomic_t *target, atomic_val_t value);
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/**
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* @brief Atomic increment.
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*
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* This routine performs an atomic increment by 1 on @a target.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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*
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* @return Previous value of @a target.
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*/
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atomic_val_t atomic_inc(atomic_t *target);
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/**
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* @brief Atomic decrement.
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*
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* This routine performs an atomic decrement by 1 on @a target.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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*
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* @return Previous value of @a target.
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*/
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atomic_val_t atomic_dec(atomic_t *target);
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/**
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* @brief Atomic get.
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*
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* This routine performs an atomic read on @a target.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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*
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* @return Value of @a target.
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*/
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atomic_val_t atomic_get(const atomic_t *target);
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/**
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* @brief Atomic get a pointer value
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*
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* This routine performs an atomic read on @a target.
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*
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* @note @atomic_api
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*
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* @param target Address of pointer variable.
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*
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* @return Value of @a target.
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*/
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atomic_ptr_val_t atomic_ptr_get(const atomic_ptr_t *target);
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/**
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* @brief Atomic get-and-set.
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*
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* This routine atomically sets @a target to @a value and returns
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* the previous value of @a target.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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* @param value Value to write to @a target.
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*
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* @return Previous value of @a target.
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*/
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atomic_val_t atomic_set(atomic_t *target, atomic_val_t value);
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/**
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* @brief Atomic get-and-set for pointer values
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*
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* This routine atomically sets @a target to @a value and returns
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* the previous value of @a target.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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* @param value Value to write to @a target.
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*
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* @return Previous value of @a target.
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*/
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atomic_ptr_val_t atomic_ptr_set(atomic_ptr_t *target, atomic_ptr_val_t value);
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/**
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* @brief Atomic clear.
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*
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* This routine atomically sets @a target to zero and returns its previous
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* value. (Hence, it is equivalent to atomic_set(target, 0).)
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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*
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* @return Previous value of @a target.
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*/
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atomic_val_t atomic_clear(atomic_t *target);
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/**
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* @brief Atomic clear of a pointer value
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*
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* This routine atomically sets @a target to zero and returns its previous
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* value. (Hence, it is equivalent to atomic_set(target, 0).)
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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*
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* @return Previous value of @a target.
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*/
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atomic_ptr_val_t atomic_ptr_clear(atomic_ptr_t *target);
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/**
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* @brief Atomic bitwise inclusive OR.
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*
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* This routine atomically sets @a target to the bitwise inclusive OR of
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* @a target and @a value.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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* @param value Value to OR.
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*
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* @return Previous value of @a target.
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*/
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atomic_val_t atomic_or(atomic_t *target, atomic_val_t value);
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/**
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* @brief Atomic bitwise exclusive OR (XOR).
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*
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* @note @atomic_api
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*
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* This routine atomically sets @a target to the bitwise exclusive OR (XOR) of
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* @a target and @a value.
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*
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* @param target Address of atomic variable.
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* @param value Value to XOR
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*
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* @return Previous value of @a target.
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*/
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atomic_val_t atomic_xor(atomic_t *target, atomic_val_t value);
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/**
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* @brief Atomic bitwise AND.
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*
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* This routine atomically sets @a target to the bitwise AND of @a target
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* and @a value.
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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* @param value Value to AND.
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*
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* @return Previous value of @a target.
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*/
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atomic_val_t atomic_and(atomic_t *target, atomic_val_t value);
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/**
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* @brief Atomic bitwise NAND.
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*
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* This routine atomically sets @a target to the bitwise NAND of @a target
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* and @a value. (This operation is equivalent to target = ~(target & value).)
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*
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* @note @atomic_api
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*
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* @param target Address of atomic variable.
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* @param value Value to NAND.
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*
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* @return Previous value of @a target.
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*/
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atomic_val_t atomic_nand(atomic_t *target, atomic_val_t value);
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/**
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* @}
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*/
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#ifdef __cplusplus
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} /* extern "C" */
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#endif
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#endif /* ZEPHYR_INCLUDE_SYS_ATOMIC_H_ */
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