New mechanism

internal/temper/temperctx_linux.go

@@ -0,0 +1,73 @@
+package temper
+
+import (
+	"context"
+	"encoding/hex"
+	"strconv"
+	"time"
+)
+
+func (t *Temper) ReadCWithContext(ctx context.Context) (float32, error) {
+	t.lock.Lock()
+	defer t.lock.Unlock()
+
+	deadline, ok := ctx.Deadline()
+	if !ok {
+		deadline = time.Time{}
+	}
+	err := t.writer.SetWriteDeadline(deadline)
+	if err != nil {
+		panic(err)
+	}
+	defer t.writer.SetDeadline(time.Time{})
+	err = t.reader.SetReadDeadline(deadline)
+	if err != nil {
+		panic(err)
+	}
+	defer t.reader.SetDeadline(time.Time{})
+	tempChan := make(chan reading)
+	go func() {
+		// prepare a buffer and get ready to read
+		// from the temper hid device
+		response := make([]byte, 8)
+		err := t.reader.SetDeadline(deadline)
+		if err != nil {
+			panic(err)
+		}
+		_, err = t.reader.Read(response)
+		if err != nil {
+			tempChan <- reading{0, err}
+			return
+		}
+		// interpret the bytes as hex
+		hexStr := hex.EncodeToString(response)
+		// extract the temperature fields from the string
+		temp := hexStr[4:8]
+		// convert the hex ints to an integer
+		tempInt, err := strconv.ParseInt(temp, 16, 64)
+		if err != nil {
+			tempChan <- reading{0, err}
+			return
+		}
+		// divide the result by 100 and send to chan
+		float := float32(tempInt) / 100
+		tempChan <- reading{error: nil, value: float}
+	}()
+	// send magic byte sequence to request a temperature reading
+	_, wErr := t.writer.Write([]byte{0, 1, 128, 51, 1, 0, 0, 0, 0})
+	if wErr != nil {
+		return 0, err
+	}
+	read := <-tempChan
+	return read.value, read.error
+}
+
+// Read the internal sensor temperature in Fahrenheit
+func (t *Temper) ReadFWithContext(ctx context.Context) (float32, error) {
+	c, err := t.ReadCWithContext(ctx)
+	if err != nil {
+		return 0, err
+	}
+	f := c*9.0/5.0 + 32.0
+	return f, err
+}