Luigi Capogrosso
110 lines
3.0 KiB
C
110 lines
3.0 KiB
C
/// MentOS, The Mentoring Operating system project
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/// @file stdatomic.h
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/// @brief
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/// @copyright (c) 2019 This file is distributed under the MIT License.
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/// See LICENSE.md for details.
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#pragma once
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#include "stdint.h"
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#include "stdbool.h"
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#include "compiler.h"
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/// @brief Standard structure for atomic operations.
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typedef volatile unsigned atomic_t;
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/// @brief At declaration, initialize an atomic_t to i.
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#define ATOMIC_INIT(i) \
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{ \
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(i) \
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}
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/// @brief The prefix used to lock.
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#define LOCK_PREFIX "\n\tlock; "
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/// @brief Compile read-write barrier.
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#define barrier() asm volatile("" : : : "memory")
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/// @brief Pause instruction to prevent excess processor bus usage.
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#define cpu_relax() asm volatile("pause\n" : : : "memory")
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// TODO: doxygen comment.
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inline static int32_t atomic_set_and_test(atomic_t const *ptr, int32_t i)
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{
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__asm__ __volatile__("xchgl %0,%1"
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: "=r"(i)
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: "m"(*(volatile unsigned *)ptr), "0"(i)
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: "memory");
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// __asm__ __volatile__("xchgl %0, %1" : "=r"(i) : "m"(ptr), "0"(i) : "memory");
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return i;
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}
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/// @brief Atomically set ptr equal to i.
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inline static void atomic_set(atomic_t *ptr, int32_t i)
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{
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atomic_set_and_test(ptr, i);
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}
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/// @brief Atomically read the integer value of ptr.
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inline static int32_t atomic_read(const atomic_t *ptr)
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{
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return READ_ONCE(*ptr);
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}
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/// @brief Atomically add i to ptr.
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inline static int32_t atomic_add(atomic_t const *ptr, int32_t i)
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{
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int result = i;
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asm volatile(LOCK_PREFIX "xaddl %0, %1"
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: "=r"(i)
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: "m"(ptr), "0"(i)
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: "memory", "cc");
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return result + i;
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}
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/// @brief Atomically subtract i from ptr.
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inline static int32_t atomic_sub(atomic_t *ptr, int32_t i)
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{
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return atomic_add(ptr, -i);
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}
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/// @brief Atomically add one to ptr.
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inline static int32_t atomic_inc(atomic_t *ptr)
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{
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return atomic_add(ptr, 1);
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}
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/// @brief Atomically subtract one from ptr.
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inline static int32_t atomic_dec(atomic_t *ptr)
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{
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return atomic_add(ptr, -1);
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}
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/// @brief Atomically add i to ptr and return true if the result is negative;
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/// otherwise false.
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inline static bool_t atomic_add_negative(atomic_t *ptr, int32_t i)
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{
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return (bool_t)(atomic_add(ptr, i) < 0);
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}
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/// @brief Atomically subtract i from ptr and return true if the result is
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/// zero; otherwise false.
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inline static bool_t atomic_sub_and_test(atomic_t *ptr, int32_t i)
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{
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return (bool_t)(atomic_sub(ptr, i) == 0);
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}
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/// @brief Atomically increment ptr by one and return true if the result is
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/// zero; false otherwise.
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inline static int32_t atomic_inc_and_test(atomic_t *ptr)
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{
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return (bool_t)(atomic_inc(ptr) == 0);
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}
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/// @brief Atomically decrement ptr by one and return true if zero; false
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/// otherwise.
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inline static int32_t atomic_dec_and_test(atomic_t *ptr)
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{
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return (bool_t)(atomic_dec(ptr) == 0);
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}
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