| /* |
| * Copyright (c) 2019 ARM Limited. |
| * |
| * SPDX-License-Identifier: MIT |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy |
| * of this software and associated documentation files (the "Software"), to |
| * deal in the Software without restriction, including without limitation the |
| * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or |
| * sell copies of the Software, and to permit persons to whom the Software is |
| * furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in all |
| * copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| * SOFTWARE. |
| */ |
| #pragma once |
| |
| #ifndef NO_MULTI_THREADING |
| |
| #include <atomic> |
| |
| namespace arm_gemm { |
| |
| class barrier { |
| private: |
| unsigned int m_threads; |
| |
| std::atomic<unsigned int> m_waiters; |
| std::atomic<unsigned int> m_leavers; |
| |
| public: |
| barrier(unsigned int threads) : m_threads(threads), m_waiters(0), m_leavers(0) { } |
| |
| /* This isn't safe if any thread is waiting... */ |
| void set_nthreads(unsigned int nthreads) { |
| m_threads = nthreads; |
| } |
| |
| void arrive_and_wait() { |
| m_waiters++; |
| |
| while (m_waiters != m_threads) { |
| ; /* spin */ |
| } |
| |
| unsigned int v = m_leavers.fetch_add(1); |
| |
| if (v == (m_threads - 1)) { |
| m_waiters -= m_threads; |
| m_leavers = 0; |
| } else { |
| while (m_leavers > 0) { |
| ; /* spin */ |
| } |
| } |
| } |
| }; |
| |
| } // namespace arm_gemm |
| |
| #else |
| |
| namespace arm_gemm { |
| |
| class barrier { |
| public: |
| barrier(unsigned int) { } |
| |
| void arrive_and_wait() { } |
| void set_nthreads(unsigned int ) { } |
| }; |
| |
| } // namespace arm_gemm |
| |
| #endif |