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55 lines
2.3 KiB
C++
Executable File
55 lines
2.3 KiB
C++
Executable File
#ifndef AWS_COMMON_RING_BUFFER_INL
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#define AWS_COMMON_RING_BUFFER_INL
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/*
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* Copyright 2010-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License").
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* You may not use this file except in compliance with the License.
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* A copy of the License is located at
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*
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* http://aws.amazon.com/apache2.0
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*
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* or in the "license" file accompanying this file. This file is distributed
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* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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* express or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*/
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#include <aws/common/ring_buffer.h>
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AWS_EXTERN_C_BEGIN
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/*
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* Checks whether atomic_ptr correctly points to a memory location within the bounds of the aws_ring_buffer
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*/
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AWS_STATIC_IMPL bool aws_ring_buffer_check_atomic_ptr(
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const struct aws_ring_buffer *ring_buf,
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const uint8_t *atomic_ptr) {
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return (atomic_ptr >= ring_buf->allocation && atomic_ptr <= ring_buf->allocation_end);
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}
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/**
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* Checks whether the ring buffer is empty
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*/
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AWS_STATIC_IMPL bool aws_ring_buffer_is_empty(const struct aws_ring_buffer *ring_buf) {
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uint8_t *head = (uint8_t *)aws_atomic_load_ptr(&ring_buf->head);
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uint8_t *tail = (uint8_t *)aws_atomic_load_ptr(&ring_buf->tail);
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return head == tail;
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}
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/**
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* Evaluates the set of properties that define the shape of all valid aws_ring_buffer structures.
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* It is also a cheap check, in the sense it run in constant time (i.e., no loops or recursion).
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*/
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AWS_STATIC_IMPL bool aws_ring_buffer_is_valid(const struct aws_ring_buffer *ring_buf) {
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uint8_t *head = (uint8_t *)aws_atomic_load_ptr(&ring_buf->head);
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uint8_t *tail = (uint8_t *)aws_atomic_load_ptr(&ring_buf->tail);
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bool head_in_range = aws_ring_buffer_check_atomic_ptr(ring_buf, head);
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bool tail_in_range = aws_ring_buffer_check_atomic_ptr(ring_buf, tail);
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/* if head points-to the first element of the buffer then tail must too */
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bool valid_head_tail = (head != ring_buf->allocation) || (tail == ring_buf->allocation);
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return ring_buf && AWS_MEM_IS_READABLE(ring_buf->allocation, ring_buf->allocation_end - ring_buf->allocation) &&
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head_in_range && tail_in_range && valid_head_tail && (ring_buf->allocator != NULL);
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}
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AWS_EXTERN_C_END
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#endif /* AWS_COMMON_RING_BUFFER_INL */
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