1 files changed, 40 insertions, 0 deletions
diff --git a/vendor/github.com/tetratelabs/wazero/internal/platform/time_windows.go b/vendor/github.com/tetratelabs/wazero/internal/platform/time_windows.go
new file mode 100644
index 000000000..58731fc8e
--- /dev/null
+++ b/vendor/github.com/tetratelabs/wazero/internal/platform/time_windows.go
@@ -0,0 +1,40 @@
+//go:build windows
+
+package platform
+
+import (
+	"math/bits"
+	"time"
+	"unsafe"
+)
+
+var (
+	_QueryPerformanceCounter   = kernel32.NewProc("QueryPerformanceCounter")
+	_QueryPerformanceFrequency = kernel32.NewProc("QueryPerformanceFrequency")
+)
+
+var qpcfreq uint64
+
+func init() {
+	_, _, _ = _QueryPerformanceFrequency.Call(uintptr(unsafe.Pointer(&qpcfreq)))
+}
+
+// On Windows, time.Time handled in time package cannot have the nanosecond precision.
+// The reason is that by default, it doesn't use QueryPerformanceCounter[1], but instead, use "interrupt time"
+// which doesn't support nanoseconds precision (though it is a monotonic) [2, 3, 4, 5].
+//
+// [1] https://learn.microsoft.com/en-us/windows/win32/api/profileapi/nf-profileapi-queryperformancecounter
+// [2] https://github.com/golang/go/blob/0cd309e12818f988693bf8e4d9f1453331dcf9f2/src/runtime/sys_windows_amd64.s#L297-L298
+// [3] https://github.com/golang/go/blob/0cd309e12818f988693bf8e4d9f1453331dcf9f2/src/runtime/os_windows.go#L549-L551
+// [4] https://github.com/golang/go/blob/master/src/runtime/time_windows.h#L7-L13
+// [5] http://web.archive.org/web/20210411000829/https://wrkhpi.wordpress.com/2007/08/09/getting-os-information-the-kuser_shared_data-structure/
+//
+// Therefore, on Windows, we directly invoke the syscall for QPC instead of time.Now or runtime.nanotime.
+// See https://github.com/golang/go/issues/31160 for example.
+func nanotime() int64 {
+	var counter uint64
+	_, _, _ = _QueryPerformanceCounter.Call(uintptr(unsafe.Pointer(&counter)))
+	hi, lo := bits.Mul64(counter, uint64(time.Second))
+	nanos, _ := bits.Div64(hi, lo, qpcfreq)
+	return int64(nanos)
+}