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internal/clock: Integrate 'now' implementations

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The Go runtime already uses QueryPerformanceCounter at runtime.nanotime.
This commit is contained in:
Hajime Hoshi 2021-04-24 22:32:44 +09:00
parent 011a524ac7
commit 2e6ecc766d
2 changed files with 0 additions and 66 deletions
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2
internal/clock/now_notwindows.go → internal/clock/now.go
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@ -12,8 +12,6 @@
// See the License for the specific language governing permissions and
// limitations under the License.
// +build !windows
package clock
import (

64
internal/clock/now_windows.go
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@ -1,64 +0,0 @@
// Copyright 2019 The Ebiten 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
//
// http://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.
package clock
import (
"fmt"
"unsafe"
"golang.org/x/sys/windows"
)
var (
kernel32 = windows.NewLazySystemDLL("kernel32")
)
var (
procQueryPerformanceFrequency = kernel32.NewProc("QueryPerformanceFrequency")
procQueryPerformanceCounter = kernel32.NewProc("QueryPerformanceCounter")
)
func queryPerformanceFrequency() int64 {
var freq int64
// TODO: Should the returned value be checked?
_, _, e := procQueryPerformanceFrequency.Call(uintptr(unsafe.Pointer(&freq)))
if e != nil && e.(windows.Errno) != 0 {
panic(fmt.Sprintf("clock: QueryPerformanceFrequency failed: errno: %d", e.(windows.Errno)))
}
return freq
}
func queryPerformanceCounter() int64 {
var ctr int64
// TODO: Should the returned value be checked?
_, _, e := procQueryPerformanceCounter.Call(uintptr(unsafe.Pointer(&ctr)))
if e != nil && e.(windows.Errno) != 0 {
panic(fmt.Sprintf("clock: QueryPerformanceCounter failed: errno: %d", e.(windows.Errno)))
}
return ctr
}
var (
freq = queryPerformanceFrequency()
initCtr = queryPerformanceCounter()
)
func now() int64 {
// Use the time duration instead of the current counter to avoid overflow.
duration := queryPerformanceCounter() - initCtr
// Use float64 not to overflow int64 values (#862).
return int64(float64(duration) / float64(freq) * 1e9)
}