| /* |
| * Copyright (c) 2016 Intel Corporation |
| * Copyright (c) 2011-2014 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. |
| */ |
| |
| /** |
| * @file Atomic ops in pure C |
| * |
| * This module provides the atomic operators for processors |
| * which do not support native atomic operations. |
| * |
| * The atomic operations are guaranteed to be atomic with respect |
| * to interrupt service routines, and to operations performed by peer |
| * processors. |
| * |
| * (originally from x86's atomic.c) |
| */ |
| |
| #include <atomic.h> |
| #include <toolchain.h> |
| #include <arch/cpu.h> |
| |
| /** |
| * |
| * @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. |
| */ |
| int atomic_cas(atomic_t *target, atomic_val_t old_value, |
| atomic_val_t new_value) |
| { |
| unsigned int key; |
| int ret = 0; |
| |
| key = irq_lock(); |
| |
| if (*target == old_value) { |
| *target = new_value; |
| ret = 1; |
| } |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |
| |
| /** |
| * |
| * @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> |
| */ |
| atomic_val_t atomic_add(atomic_t *target, atomic_val_t value) |
| { |
| unsigned int key; |
| atomic_val_t ret; |
| |
| key = irq_lock(); |
| |
| ret = *target; |
| *target += value; |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |
| |
| /** |
| * |
| * @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> |
| */ |
| atomic_val_t atomic_sub(atomic_t *target, atomic_val_t value) |
| { |
| unsigned int key; |
| atomic_val_t ret; |
| |
| key = irq_lock(); |
| |
| ret = *target; |
| *target -= value; |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |
| |
| /** |
| * |
| * @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 |
| */ |
| atomic_val_t atomic_inc(atomic_t *target) |
| { |
| unsigned int key; |
| atomic_val_t ret; |
| |
| key = irq_lock(); |
| |
| ret = *target; |
| (*target)++; |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |
| |
| /** |
| * |
| * @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 |
| */ |
| atomic_val_t atomic_dec(atomic_t *target) |
| { |
| unsigned int key; |
| atomic_val_t ret; |
| |
| key = irq_lock(); |
| |
| ret = *target; |
| (*target)--; |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |
| |
| /** |
| * |
| * @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> |
| */ |
| atomic_val_t atomic_get(const atomic_t *target) |
| { |
| return *target; |
| } |
| |
| /** |
| * |
| * @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> |
| */ |
| atomic_val_t atomic_set(atomic_t *target, atomic_val_t value) |
| { |
| unsigned int key; |
| atomic_val_t ret; |
| |
| key = irq_lock(); |
| |
| ret = *target; |
| *target = value; |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |
| |
| /** |
| * |
| * @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> |
| */ |
| atomic_val_t atomic_clear(atomic_t *target) |
| { |
| unsigned int key; |
| atomic_val_t ret; |
| |
| key = irq_lock(); |
| |
| ret = *target; |
| *target = 0; |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |
| |
| /** |
| * |
| * @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> |
| */ |
| atomic_val_t atomic_or(atomic_t *target, atomic_val_t value) |
| { |
| unsigned int key; |
| atomic_val_t ret; |
| |
| key = irq_lock(); |
| |
| ret = *target; |
| *target |= value; |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |
| |
| /** |
| * |
| * @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> |
| */ |
| atomic_val_t atomic_xor(atomic_t *target, atomic_val_t value) |
| { |
| unsigned int key; |
| atomic_val_t ret; |
| |
| key = irq_lock(); |
| |
| ret = *target; |
| *target ^= value; |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |
| |
| /** |
| * |
| * @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> |
| */ |
| atomic_val_t atomic_and(atomic_t *target, atomic_val_t value) |
| { |
| unsigned int key; |
| atomic_val_t ret; |
| |
| key = irq_lock(); |
| |
| ret = *target; |
| *target &= value; |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |
| |
| /** |
| * |
| * @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. |
| * |
| * @param target the memory location to be modified |
| * @param value the value to NAND |
| * |
| * @return The previous value from <target> |
| */ |
| atomic_val_t atomic_nand(atomic_t *target, atomic_val_t value) |
| { |
| unsigned int key; |
| atomic_val_t ret; |
| |
| key = irq_lock(); |
| |
| ret = *target; |
| *target = ~(*target & value); |
| |
| irq_unlock(key); |
| |
| return ret; |
| } |