1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "absl/base/internal/unscaledcycleclock.h"
16
17 #if ABSL_USE_UNSCALED_CYCLECLOCK
18
19 #if defined(_WIN32)
20 #include <intrin.h>
21 #endif
22
23 #if defined(__powerpc__) || defined(__ppc__)
24 #ifdef __GLIBC__
25 #include <sys/platform/ppc.h>
26 #elif defined(__FreeBSD__)
27 #include <sys/sysctl.h>
28 #include <sys/types.h>
29 #endif
30 #endif
31
32 #include "absl/base/internal/sysinfo.h"
33
34 namespace absl {
35 ABSL_NAMESPACE_BEGIN
36 namespace base_internal {
37
38 #if defined(__i386__)
39
Now()40 int64_t UnscaledCycleClock::Now() {
41 int64_t ret;
42 __asm__ volatile("rdtsc" : "=A"(ret));
43 return ret;
44 }
45
Frequency()46 double UnscaledCycleClock::Frequency() {
47 return base_internal::NominalCPUFrequency();
48 }
49
50 #elif defined(__x86_64__)
51
52 double UnscaledCycleClock::Frequency() {
53 return base_internal::NominalCPUFrequency();
54 }
55
56 #elif defined(__powerpc__) || defined(__ppc__)
57
58 int64_t UnscaledCycleClock::Now() {
59 #ifdef __GLIBC__
60 return __ppc_get_timebase();
61 #else
62 #ifdef __powerpc64__
63 int64_t tbr;
64 asm volatile("mfspr %0, 268" : "=r"(tbr));
65 return tbr;
66 #else
67 int32_t tbu, tbl, tmp;
68 asm volatile(
69 "0:\n"
70 "mftbu %[hi32]\n"
71 "mftb %[lo32]\n"
72 "mftbu %[tmp]\n"
73 "cmpw %[tmp],%[hi32]\n"
74 "bne 0b\n"
75 : [ hi32 ] "=r"(tbu), [ lo32 ] "=r"(tbl), [ tmp ] "=r"(tmp));
76 return (static_cast<int64_t>(tbu) << 32) | tbl;
77 #endif
78 #endif
79 }
80
81 double UnscaledCycleClock::Frequency() {
82 #ifdef __GLIBC__
83 return __ppc_get_timebase_freq();
84 #elif defined(_AIX)
85 // This is the same constant value as returned by
86 // __ppc_get_timebase_freq().
87 return static_cast<double>(512000000);
88 #elif defined(__FreeBSD__)
89 static once_flag init_timebase_frequency_once;
90 static double timebase_frequency = 0.0;
91 base_internal::LowLevelCallOnce(&init_timebase_frequency_once, [&]() {
92 size_t length = sizeof(timebase_frequency);
93 sysctlbyname("kern.timecounter.tc.timebase.frequency", &timebase_frequency,
94 &length, nullptr, 0);
95 });
96 return timebase_frequency;
97 #else
98 #error Must implement UnscaledCycleClock::Frequency()
99 #endif
100 }
101
102 #elif defined(__aarch64__)
103
104 // System timer of ARMv8 runs at a different frequency than the CPU's.
105 // The frequency is fixed, typically in the range 1-50MHz. It can be
106 // read at CNTFRQ special register. We assume the OS has set up
107 // the virtual timer properly.
108 int64_t UnscaledCycleClock::Now() {
109 int64_t virtual_timer_value;
110 asm volatile("mrs %0, cntvct_el0" : "=r"(virtual_timer_value));
111 return virtual_timer_value;
112 }
113
114 double UnscaledCycleClock::Frequency() {
115 uint64_t aarch64_timer_frequency;
116 asm volatile("mrs %0, cntfrq_el0" : "=r"(aarch64_timer_frequency));
117 return aarch64_timer_frequency;
118 }
119
120 #elif defined(__riscv)
121
122 int64_t UnscaledCycleClock::Now() {
123 int64_t virtual_timer_value;
124 asm volatile("rdcycle %0" : "=r"(virtual_timer_value));
125 return virtual_timer_value;
126 }
127
128 double UnscaledCycleClock::Frequency() {
129 return base_internal::NominalCPUFrequency();
130 }
131
132 #elif defined(_M_IX86) || defined(_M_X64)
133
134 #pragma intrinsic(__rdtsc)
135
136 int64_t UnscaledCycleClock::Now() { return __rdtsc(); }
137
138 double UnscaledCycleClock::Frequency() {
139 return base_internal::NominalCPUFrequency();
140 }
141
142 #endif
143
144 } // namespace base_internal
145 ABSL_NAMESPACE_END
146 } // namespace absl
147
148 #endif // ABSL_USE_UNSCALED_CYCLECLOCK
149