Module: AlsaRawMIDI::API::Input

Extended by:
Input
Included in:
Input
Defined in:
lib/alsa-rawmidi/api.rb

Overview

Wrapper for ALSA methods dealing with input

Constant Summary collapse

BUFFER_SIZE = 
256

Instance Method Summary collapse

Instance Method Details

#open(id) ⇒ Fixnum

Open the output with the given ID

Parameters:

  • id (Fixnum)

Returns:

  • (Fixnum) 


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# File 'lib/alsa-rawmidi/api.rb', line 246

def open(id)
  API::Device.open(id) do |pointer|
    API.snd_rawmidi_open(pointer, nil, id,  API::CONSTANTS[:SND_RAWMIDI_NONBLOCK])
  end
end

#poll(handle) ⇒ String

Get the next bytes from the buffer

Returns:

  • (String) 


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# File 'lib/alsa-rawmidi/api.rb', line 254

def poll(handle)
  buffer = FFI::MemoryPointer.new(:uint8, BUFFER_SIZE)
  if (err = API.snd_rawmidi_read(handle, buffer, BUFFER_SIZE)) < 0
    raise "Can't read MIDI input: #{API.snd_strerror(err)}" unless err.eql?(-11)
  end
  # Upon success, err is positive and equal to the number of bytes read
  # into the buffer.
  if err > 0
    bytes = buffer.get_bytes(0,err).unpack("a*").first.unpack("H*")
    bytes.first.upcase
  end
end