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/* atomic operations */
/*
* Copyright (c) 1997-2015, Wind River Systems, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef __ATOMIC_H__
#define __ATOMIC_H__
#ifdef __cplusplus
extern "C" {
#endif
typedef int atomic_t;
typedef atomic_t atomic_val_t;
#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
/**
*
* @brief Atomic compare-and-set primitive
*
* This routine provides the compare-and-set operator. If the original value at
* <target> equals <oldValue>, then <newValue> is stored at <target> and the
* function returns 1.
*
* If the original value at <target> does not equal <oldValue>, then the store
* is not done and the function returns 0.
*
* The reading of the original value at <target>, the comparison,
* and the write of the new value (if it occurs) all happen atomically with
* respect to both interrupts and accesses of other processors to <target>.
*
* @param target address to be tested
* @param old_value value to compare against
* @param new_value value to compare against
* @return Returns 1 if <new_value> is written, 0 otherwise.
*/
static inline int atomic_cas(atomic_t *target, atomic_val_t old_value,
atomic_val_t new_value)
{
return __atomic_compare_exchange_n(target, &old_value, new_value,
0, __ATOMIC_SEQ_CST,
__ATOMIC_SEQ_CST);
}
/**
*
* @brief Atomic addition primitive
*
* This routine provides the atomic addition operator. The <value> is
* atomically added to the value at <target>, placing the result at <target>,
* and the old value from <target> is returned.
*
* @param target memory location to add to
* @param value the value to add
*
* @return The previous value from <target>
*/
static inline atomic_val_t atomic_add(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_add(target, value, __ATOMIC_SEQ_CST);
}
/**
*
* @brief Atomic subtraction primitive
*
* This routine provides the atomic subtraction operator. The <value> is
* atomically subtracted from the value at <target>, placing the result at
* <target>, and the old value from <target> is returned.
*
* @param target the memory location to subtract from
* @param value the value to subtract
*
* @return The previous value from <target>
*/
static inline atomic_val_t atomic_sub(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_sub(target, value, __ATOMIC_SEQ_CST);
}
/**
*
* @brief Atomic increment primitive
*
* @param target memory location to increment
*
* This routine provides the atomic increment operator. The value at <target>
* is atomically incremented by 1, and the old value from <target> is returned.
*
* @return The value from <target> before the increment
*/
static inline atomic_val_t atomic_inc(atomic_t *target)
{
return atomic_add(target, 1);
}
/**
*
* @brief Atomic decrement primitive
*
* @param target memory location to decrement
*
* This routine provides the atomic decrement operator. The value at <target>
* is atomically decremented by 1, and the old value from <target> is returned.
*
* @return The value from <target> prior to the decrement
*/
static inline atomic_val_t atomic_dec(atomic_t *target)
{
return atomic_sub(target, 1);
}
/**
*
* @brief Atomic get primitive
*
* @param target memory location to read from
*
* This routine provides the atomic get primitive to atomically read
* a value from <target>. It simply does an ordinary load. Note that <target>
* is expected to be aligned to a 4-byte boundary.
*
* @return The value read from <target>
*/
static inline atomic_val_t atomic_get(const atomic_t *target)
{
return __atomic_load_n(target, __ATOMIC_SEQ_CST);
}
/**
*
* @brief Atomic get-and-set primitive
*
* This routine provides the atomic set operator. The <value> is atomically
* written at <target> and the previous value at <target> is returned.
*
* @param target the memory location to write to
* @param value the value to write
*
* @return The previous value from <target>
*/
static inline atomic_val_t atomic_set(atomic_t *target, atomic_val_t value)
{
/* This builtin, as described by Intel, is not a traditional
* test-and-set operation, but rather an atomic exchange operation. It
* writes value into *ptr, and returns the previous contents of *ptr.
*/
return __atomic_exchange_n(target, value, __ATOMIC_SEQ_CST);
}
/**
*
* @brief Atomic clear primitive
*
* This routine provides the atomic clear operator. The value of 0 is atomically
* written at <target> and the previous value at <target> is returned. (Hence,
* atomic_clear(pAtomicVar) is equivalent to atomic_set(pAtomicVar, 0).)
*
* @param target the memory location to write
*
* @return The previous value from <target>
*/
static inline atomic_val_t atomic_clear(atomic_t *target)
{
return atomic_set(target, 0);
}
/**
*
* @brief Atomic bitwise inclusive OR primitive
*
* This routine provides the atomic bitwise inclusive OR operator. The <value>
* is atomically bitwise OR'ed with the value at <target>, placing the result
* at <target>, and the previous value at <target> is returned.
*
* @param target the memory location to be modified
* @param value the value to OR
*
* @return The previous value from <target>
*/
static inline atomic_val_t atomic_or(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_or(target, value, __ATOMIC_SEQ_CST);
}
/**
*
* @brief Atomic bitwise exclusive OR (XOR) primitive
*
* This routine provides the atomic bitwise exclusive OR operator. The <value>
* is atomically bitwise XOR'ed with the value at <target>, placing the result
* at <target>, and the previous value at <target> is returned.
*
* @param target the memory location to be modified
* @param value the value to XOR
*
* @return The previous value from <target>
*/
static inline atomic_val_t atomic_xor(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_xor(target, value, __ATOMIC_SEQ_CST);
}
/**
*
* @brief Atomic bitwise AND primitive
*
* This routine provides the atomic bitwise AND operator. The <value> is
* atomically bitwise AND'ed with the value at <target>, placing the result
* at <target>, and the previous value at <target> is returned.
*
* @param target the memory location to be modified
* @param value the value to AND
*
* @return The previous value from <target>
*/
static inline atomic_val_t atomic_and(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_and(target, value, __ATOMIC_SEQ_CST);
}
/**
*
* @brief Atomic bitwise NAND primitive
*
* This routine provides the atomic bitwise NAND operator. The <value> is
* atomically bitwise NAND'ed with the value at <target>, placing the result
* at <target>, and the previous value at <target> is returned.
*
* The operation here is equivalent to *target = ~(tmp & value)
*
* @param target the memory location to be modified
* @param value the value to NAND
*
* @return The previous value from <target>
*/
static inline atomic_val_t atomic_nand(atomic_t *target, atomic_val_t value)
{
return __atomic_fetch_nand(target, value, __ATOMIC_SEQ_CST);
}
#else
extern atomic_val_t atomic_add(atomic_t *target, atomic_val_t value);
extern atomic_val_t atomic_and(atomic_t *target, atomic_val_t value);
extern atomic_val_t atomic_dec(atomic_t *target);
extern atomic_val_t atomic_inc(atomic_t *target);
extern atomic_val_t atomic_nand(atomic_t *target, atomic_val_t value);
extern atomic_val_t atomic_or(atomic_t *target, atomic_val_t value);
extern atomic_val_t atomic_sub(atomic_t *target, atomic_val_t value);
extern atomic_val_t atomic_xor(atomic_t *target, atomic_val_t value);
extern atomic_val_t atomic_clear(atomic_t *target);
extern atomic_val_t atomic_get(const atomic_t *target);
extern atomic_val_t atomic_set(atomic_t *target, atomic_val_t value);
extern int atomic_cas(atomic_t *target, atomic_val_t oldValue,
atomic_val_t newValue);
#endif /* CONFIG_ATOMIC_OPERATIONS_BUILTIN */
#define ATOMIC_INIT(i) {(i)}
#define ATOMIC_BITS (sizeof(atomic_val_t) * 8)
#define ATOMIC_MASK(bit) (1 << ((bit) & (ATOMIC_BITS - 1)))
#define ATOMIC_ELEM(addr, bit) ((addr) + ((bit) / ATOMIC_BITS))
/** @def ATOMIC_DEFINE
* @brief Helper to declare an atomic_t array.
*
* A helper to define an atomic_t array based on the number of needed
* bits, e.g. any bit count of 32 or less will produce a single-element
* array.
*
* @param name Name of atomic_t array.
* @param num_bits Maximum number of bits needed.
*
* @return n/a
*/
#define ATOMIC_DEFINE(name, num_bits) \
atomic_t name[1 + ((num_bits) - 1) / ATOMIC_BITS]
/** @brief Test whether a bit is set
*
* Test whether bit number bit is set or not.
*
* Also works for an array of multiple atomic_t variables, in which
* case the bit number may go beyond the number of bits in a single
* atomic_t variable.
*
* @param addr base address to start counting from
* @param bit bit number counted from the base address
*
* @return 1 if the bit was set, 0 if it wasn't
*/
static inline int atomic_test_bit(const atomic_t *addr, int bit)
{
atomic_val_t val = atomic_get(ATOMIC_ELEM(addr, bit));
return (1 & (val >> (bit & (ATOMIC_BITS - 1))));
}
/** @brief Clear a bit and return its old value
*
* Atomically clear a bit and return its old value.
*
* Also works for an array of multiple atomic_t variables, in which
* case the bit number may go beyond the number of bits in a single
* atomic_t variable.
*
* @param addr base address to start counting from
* @param bit bit number counted from the base address
*
* @return 1 if the bit was set, 0 if it wasn't
*/
static inline int atomic_test_and_clear_bit(atomic_t *addr, int bit)
{
atomic_val_t mask = ATOMIC_MASK(bit);
atomic_val_t old;
old = atomic_and(ATOMIC_ELEM(addr, bit), ~mask);
return (old & mask) != 0;
}
/** @brief Set a bit and return its old value
*
* Atomically set a bit and return its old value.
*
* Also works for an array of multiple atomic_t variables, in which
* case the bit number may go beyond the number of bits in a single
* atomic_t variable.
*
* @param addr base address to start counting from
* @param bit bit number counted from the base address
*
* @return 1 if the bit was set, 0 if it wasn't
*/
static inline int atomic_test_and_set_bit(atomic_t *addr, int bit)
{
atomic_val_t mask = ATOMIC_MASK(bit);
atomic_val_t old;
old = atomic_or(ATOMIC_ELEM(addr, bit), mask);
return (old & mask) != 0;
}
/** @brief Clear a bit
*
* Atomically clear a bit.
*
* Also works for an array of multiple atomic_t variables, in which
* case the bit number may go beyond the number of bits in a single
* atomic_t variable.
*
* @param addr base address to start counting from
* @param bit bit number counted from the base address
*/
static inline void atomic_clear_bit(atomic_t *addr, int bit)
{
atomic_val_t mask = ATOMIC_MASK(bit);
atomic_and(ATOMIC_ELEM(addr, bit), ~mask);
}
/** @brief Set a bit
*
* Atomically set a bit.
*
* Also works for an array of multiple atomic_t variables, in which
* case the bit number may go beyond the number of bits in a single
* atomic_t variable.
*
* @param addr base address to start counting from
* @param bit bit number counted from the base address
*/
static inline void atomic_set_bit(atomic_t *addr, int bit)
{
atomic_val_t mask = ATOMIC_MASK(bit);
atomic_or(ATOMIC_ELEM(addr, bit), mask);
}
#ifdef __cplusplus
}
#endif
#endif /* __ATOMIC_H__ */