// Copyright 2017 The Abseil Authors.

//

// 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

//

//      https://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.

#include "absl/base/internal/unscaledcycleclock.h"

#if ABSL_USE_UNSCALED_CYCLECLOCK

#if defined(_WIN32)

#include <intrin.h>

#endif

#if defined(__powerpc__) || defined(__ppc__)

#ifdef __GLIBC__

#include <sys/platform/ppc.h>

#elif defined(__FreeBSD__)

// clang-format off

// This order does actually matter =(.

#include <sys/types.h>

#include <sys/sysctl.h>

// clang-format on

#include "absl/base/call_once.h"

#endif

#endif

#include "absl/base/internal/sysinfo.h"

namespace absl {

ABSL_NAMESPACE_BEGIN

namespace base_internal {

#if defined(__i386__)

int64_t UnscaledCycleClock::Now() {

  int64_t ret;

  __asm__ volatile("rdtsc" : "=A"(ret));

  return ret;

}

double UnscaledCycleClock::Frequency() {

  return base_internal::NominalCPUFrequency();

}

#elif defined(__x86_64__)

double UnscaledCycleClock::Frequency() {

  return base_internal::NominalCPUFrequency();

}

#elif defined(__powerpc__) || defined(__ppc__)

int64_t UnscaledCycleClock::Now() {

#ifdef __GLIBC__

  return __ppc_get_timebase();

#else

#ifdef __powerpc64__

  int64_t tbr;

  asm volatile("mfspr %0, 268" : "=r"(tbr));

  return tbr;

#else

  int32_t tbu, tbl, tmp;

  asm volatile(

      "mftbu %[hi32]\n"

      "mftb %[lo32]\n"

      "mftbu %[tmp]\n"

      "cmpw %[tmp],%[hi32]\n"

      "bne $-16\n"  // Retry on failure.

      : [hi32] "=r"(tbu), [lo32] "=r"(tbl), [tmp] "=r"(tmp));

  return (static_cast<int64_t>(tbu) << 32) | tbl;

#endif

#endif

}

double UnscaledCycleClock::Frequency() {

#ifdef __GLIBC__

  return __ppc_get_timebase_freq();

#elif defined(_AIX)

  // This is the same constant value as returned by

  // __ppc_get_timebase_freq().

  return static_cast<double>(512000000);

#elif defined(__FreeBSD__)

  static once_flag init_timebase_frequency_once;

  static double timebase_frequency = 0.0;

  base_internal::LowLevelCallOnce(&init_timebase_frequency_once, [&]() {

    size_t length = sizeof(timebase_frequency);

    sysctlbyname("kern.timecounter.tc.timebase.frequency", &timebase_frequency,

                 &length, nullptr, 0);

  });

  return timebase_frequency;

#else

#error Must implement UnscaledCycleClock::Frequency()

#endif

}

#elif defined(__aarch64__)

// System timer of ARMv8 runs at a different frequency than the CPU's.

// The frequency is fixed, typically in the range 1-50MHz.  It can be

// read at CNTFRQ special register.  We assume the OS has set up

// the virtual timer properly.

int64_t UnscaledCycleClock::Now() {

  int64_t virtual_timer_value;

  asm volatile("mrs %0, cntvct_el0" : "=r"(virtual_timer_value));

  return virtual_timer_value;

}

double UnscaledCycleClock::Frequency() {

  uint64_t aarch64_timer_frequency;

  asm volatile("mrs %0, cntfrq_el0" : "=r"(aarch64_timer_frequency));

  return aarch64_timer_frequency;

}

#elif defined(_M_IX86) || defined(_M_X64)

#pragma intrinsic(__rdtsc)

int64_t UnscaledCycleClock::Now() { return __rdtsc(); }

double UnscaledCycleClock::Frequency() {

  return base_internal::NominalCPUFrequency();

}

#endif

}  // namespace base_internal

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_USE_UNSCALED_CYCLECLOCK