Flesh it out more.

devices/geiger/gqgmc.go

@@ -8,6 +8,7 @@
 package geiger
 
 import (
+	"errors"
 	"fmt"
 	"time"
 
@@ -356,17 +357,13 @@ func (gc *GQGMCCounter) sendCmd(cmd []byte) {
 }
 
 func (gc *GQGMCCounter) readCmdReturn(length uint32) ([]byte, error) {
-	// Now read the returned raw byte string. Do this by reading one byte
-	// at a time until the requested number of bytes are attained. However,
-	// the serial port has been setup to timeout each read attempt. So if
-	// after N calls to read, we haven't yet read all N bytes, declare
-	// a failure. The read is done this way to avoid an indefinite blocking
-	// situation when 0 bytes are returned by the GQ GMC. The only good thing
-	// about this methodology is that the largest possible read is only 4K
-	// for the history data. So the read never really takes that much time.
-	//for(uint32_t i=0; i<retbytes; i++)
-	//  rcvd += read(mUSB_serial, inp, 1);
-	//  inp   = &retdata[rcvd];
-	//  if (rcvd >= retbytes) break;
-	return nil, nil
+	buf := make([]byte, length)
+	n, err := gc.port.Read(buf)
+	if err != nil {
+		return nil, err
+	}
+	if uint32(n) != length {
+		return nil, errors.New("Short read")
+	}
+	return buf, nil
 }