Write ioctl is not guaranteed to write requested number of frames

[djadala]

https://github.com/yobert/alsa/blob/d079056f5370c525161fa2ec4b72d0dfd5ef48b8/device.go#L256

Hi, sometimes write method write less number of frames, here is how i fixed this:

func (device *Device) write1(buf []byte, frames int) (int, error) {
	x := pcm.XferI{
		Buf:    uintptr(unsafe.Pointer(&buf[0])),
		Frames: alsatype.Uframes(frames),
	}
	err := ioctl(device.fh.Fd(), ioctl_encode_ptr(cmdWrite, &x, cmdPCMWriteIFrames), &x)
        written := alsatype.Uframes(frames)
	if  err == syscall.EAGAIN {
		return written, nil
	} 
	return written, err
}


func (device *Device) Write(buf []byte, framesize int) error {

	for len(buf) > 0 {
		w, err := dev.write1(buf, len(buf)/framesize)
		if err != nil {
			return  err
		}
		buf = buf[w*framesize:]
	}
}

i not going to send PR, please update from this issue,

Regards

PS May be Read can also read less that requested frames ?

[yobert]

Great report! That makes sense. I was hoping it would block until it was able to write as many frames as requested. I'll make a PR for this sometime.