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Michael Brooksfe2b2a82024-03-29 17:34:32 +00001/*
2 * Copyright 2024 Google LLC
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef BENCHMARKS_CYCLE_COUNT_H_
18#define BENCHMARKS_CYCLE_COUNT_H_
19
20inline uint64_t mcycle_read(void) {
21 uint32_t cycle_low = 0;
22 uint32_t cycle_high = 0;
23 uint32_t cycle_high_2 = 0;
24 asm volatile(
25 "1:"
26 " csrr %0, mcycleh;" // Read `mcycleh`.
27 " csrr %1, mcycle;" // Read `mcycle`.
28 " csrr %2, mcycleh;" // Read `mcycleh` again.
29 " bne %0, %2, 1b;"
30 : "=r"(cycle_high), "=r"(cycle_low), "=r"(cycle_high_2)
31 :);
32 return static_cast<uint64_t>(cycle_high) << 32 | cycle_low;
33}
34
35#endif // #ifndef BENCHMARKS_CYCLE_COUNT_H_