add: humidity (WIP)

vendor/periph.io/x/periph/host/cpu/cpu.go

@@ -0,0 +1,83 @@
+// Copyright 2016 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package cpu
+
+import (
+	"io"
+	"io/ioutil"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"periph.io/x/periph/host/fs"
+)
+
+// MaxSpeed returns the processor maximum speed in Hz.
+//
+// Returns 0 if it couldn't be calculated.
+func MaxSpeed() int64 {
+	if isLinux {
+		return getMaxSpeedLinux()
+	}
+	return 0
+}
+
+// Nanospin spins for a short amount of time doing a busy loop.
+//
+// This function should be called with durations of 10µs or less.
+func Nanospin(d time.Duration) {
+	// TODO(maruel): Use runtime.LockOSThread()?
+	if isLinux {
+		nanospinLinux(d)
+	} else {
+		nanospinTime(d)
+	}
+}
+
+//
+
+var (
+	mu       sync.Mutex
+	maxSpeed int64 = -1
+	openFile       = openFileOrig
+)
+
+func openFileOrig(path string, flag int) (io.ReadCloser, error) {
+	f, err := fs.Open(path, flag)
+	if err != nil {
+		return nil, err
+	}
+	return f, nil
+}
+
+func getMaxSpeedLinux() int64 {
+	mu.Lock()
+	defer mu.Unlock()
+	if maxSpeed == -1 {
+		maxSpeed = 0
+		if f, err := openFile("/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq", os.O_RDONLY); err == nil {
+			defer f.Close()
+			if b, err := ioutil.ReadAll(f); err == nil {
+				s := strings.TrimSpace(string(b))
+				if i, err := strconv.ParseInt(s, 10, 64); err == nil {
+					// Weirdly, the speed is listed as khz. :(
+					maxSpeed = i * 1000
+				}
+			}
+		}
+	}
+	return maxSpeed
+}
+
+func nanospinTime(d time.Duration) {
+	// TODO(maruel): That's not optimal; it's actually pretty bad.
+	// time.Sleep() sleeps for really too long, calling it repeatedly with
+	// minimal value will give the caller a wake rate of 5KHz or so, depending on
+	// the host. This makes it useless for bitbanging protocol implementations.
+	for start := time.Now(); time.Since(start) < d; {
+	}
+}

vendor/periph.io/x/periph/host/cpu/cpu_linux.go

@@ -0,0 +1,22 @@
+// Copyright 2016 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package cpu
+
+import (
+	"syscall"
+	"time"
+)
+
+const isLinux = true
+
+func nanospinLinux(d time.Duration) {
+	// runtime.nanotime() is not exported so it cannot be used to busy loop for
+	// very short sleep (10µs or less).
+	time := syscall.NsecToTimespec(d.Nanoseconds())
+	leftover := syscall.Timespec{}
+	for syscall.Nanosleep(&time, &leftover) != nil {
+		time = leftover
+	}
+}

vendor/periph.io/x/periph/host/cpu/cpu_other.go

@@ -0,0 +1,14 @@
+// Copyright 2016 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+// +build !linux
+
+package cpu
+
+import "time"
+
+const isLinux = false
+
+func nanospinLinux(d time.Duration) {
+}

vendor/periph.io/x/periph/host/cpu/doc.go

@@ -0,0 +1,6 @@
+// Copyright 2016 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+// Package cpu implements functions relating to the host CPU itself.
+package cpu