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102 lines
3.3 KiB
102 lines
3.3 KiB
/*
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* Copyright (C) 2020 The Android Open Source Project
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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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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <assert.h>
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#include <string>
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namespace android {
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namespace hardware {
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enum MQFlavor : uint32_t {
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/*
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* kSynchronizedReadWrite represents the wait-free synchronized flavor of the
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* FMQ. It is intended to be have a single reader and single writer.
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* Attempts to overflow/underflow returns a failure.
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*/
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kSynchronizedReadWrite = 0x01,
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/*
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* kUnsynchronizedWrite represents the flavor of FMQ where writes always
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* succeed. This flavor allows one writer and many readers. A read operation
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* can detect an overwrite and reset the read counter.
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*/
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kUnsynchronizedWrite = 0x02
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};
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struct GrantorDescriptor {
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uint32_t flags __attribute__((aligned(4)));
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uint32_t fdIndex __attribute__((aligned(4)));
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uint32_t offset __attribute__((aligned(4)));
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uint64_t extent __attribute__((aligned(8)));
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};
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static_assert(offsetof(GrantorDescriptor, flags) == 0, "wrong offset");
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static_assert(offsetof(GrantorDescriptor, fdIndex) == 4, "wrong offset");
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static_assert(offsetof(GrantorDescriptor, offset) == 8, "wrong offset");
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static_assert(offsetof(GrantorDescriptor, extent) == 16, "wrong offset");
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static_assert(sizeof(GrantorDescriptor) == 24, "wrong size");
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static_assert(__alignof(GrantorDescriptor) == 8, "wrong alignment");
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namespace details {
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void logError(const std::string& message);
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void errorWriteLog(int tag, const char* message);
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typedef uint64_t RingBufferPosition;
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enum GrantorType : int { READPTRPOS = 0, WRITEPTRPOS, DATAPTRPOS, EVFLAGWORDPOS };
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/*
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* There should at least be GrantorDescriptors for the read counter, write
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* counter and data buffer. A GrantorDescriptor for an EventFlag word is
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* not required if there is no need for blocking FMQ operations.
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*/
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static constexpr int32_t kMinGrantorCount = DATAPTRPOS + 1;
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/*
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* Minimum number of GrantorDescriptors required if EventFlag support is
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* needed for blocking FMQ operations.
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*/
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static constexpr int32_t kMinGrantorCountForEvFlagSupport = EVFLAGWORDPOS + 1;
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static inline size_t alignToWordBoundary(size_t length) {
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constexpr size_t kAlignmentSize = 64;
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if (kAlignmentSize % __WORDSIZE != 0) {
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#ifdef __BIONIC__
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__assert(__FILE__, __LINE__, "Incompatible word size");
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#endif
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}
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/*
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* Check if alignment to word boundary would cause an overflow.
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*/
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if (length > SIZE_MAX - kAlignmentSize / 8 + 1) {
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#ifdef __BIONIC__
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__assert(__FILE__, __LINE__, "Queue size too large");
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#endif
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}
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return (length + kAlignmentSize / 8 - 1) & ~(kAlignmentSize / 8 - 1U);
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}
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static inline size_t isAlignedToWordBoundary(size_t offset) {
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constexpr size_t kAlignmentSize = 64;
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return (offset & (kAlignmentSize / 8 - 1)) == 0;
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}
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} // namespace details
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} // namespace hardware
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} // namespace android
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