Module: Webmidi::Message::Parser

Defined in:
lib/webmidi/message/parser.rb

Constant Summary collapse

CHANNEL_LENGTHS = 
{
  0x80 => 3,
  0x90 => 3,
  0xA0 => 3,
  0xB0 => 3,
  0xC0 => 2,
  0xD0 => 2,
  0xE0 => 3
}.freeze
SYSTEM_LENGTHS = 
{
  0xF1 => 2,
  0xF2 => 3,
  0xF3 => 2,
  0xF6 => 1,
  0xF8 => 1,
  0xFA => 1,
  0xFB => 1,
  0xFC => 1,
  0xFE => 1,
  0xFF => 1
}.freeze
REAL_TIME_STATUSES = 
[0xF8, 0xFA, 0xFB, 0xFC, 0xFE, 0xFF].freeze
INVALID_SYSTEM_STATUSES = 
[0xF4, 0xF5, 0xF7, 0xF9, 0xFD].freeze

Class Method Summary collapse

Class Method Details

.parse_many(bytes, normalize_note_on_zero: true) ⇒ Object 



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# File 'lib/webmidi/message/parser.rb', line 68

def parse_many(bytes, normalize_note_on_zero: true)
  parse_stream(bytes, running_status: false, normalize_note_on_zero: normalize_note_on_zero)
end

.parse_single(bytes, normalize_note_on_zero: true) ⇒ Object

Raises:



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# File 'lib/webmidi/message/parser.rb', line 34

def parse_single(bytes, normalize_note_on_zero: true)
  bytes = validate_bytes!(bytes)
  raise InvalidMessageError, "Empty message" if bytes.empty?

  status = bytes[0]
  validate_status!(status)

  if status == 0xF0
    return parse_sysex(bytes)
  end

  validate_exact_length!(bytes, message_length(status))
  validate_data_bytes!(bytes[1..])

  case status & 0xF0
  when 0x80
    parse_note_off(bytes)
  when 0x90
    parse_note_on(bytes, normalize_note_on_zero: normalize_note_on_zero)
  when 0xA0
    parse_polyphonic_pressure(bytes)
  when 0xB0
    parse_control_change(bytes)
  when 0xC0
    parse_program_change(bytes)
  when 0xD0
    parse_channel_pressure(bytes)
  when 0xE0
    parse_pitch_bend(bytes)
  when 0xF0
    parse_system(bytes)
  end
end

.parse_stream(bytes, running_status: true, normalize_note_on_zero: true) ⇒ Object 



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# File 'lib/webmidi/message/parser.rb', line 72

def parse_stream(bytes, running_status: true, normalize_note_on_zero: true)
  bytes = validate_bytes!(bytes)
  messages = []
  pending = []
  needed = nil
  last_channel_status = nil

  bytes.each do |byte|
    if real_time_status?(byte)
      messages << parse_single([byte], normalize_note_on_zero: normalize_note_on_zero)
      next
    end

    if pending.empty?
      if byte < 0x80
        raise InvalidMessageError, "Data byte #{format_byte(byte)} without status" unless running_status && last_channel_status

        pending = [last_channel_status, byte]
        needed = message_length(last_channel_status)
      else
        validate_status!(byte)
        pending = [byte]
        needed = (byte == 0xF0) ? :sysex : message_length(byte)
        last_channel_status = channel_status?(byte) ? byte : nil
      end
    elsif needed == :sysex
      validate_sysex_data_or_end!(byte)
      pending << byte
    else
      raise InvalidMessageError, "Unexpected status byte #{format_byte(byte)} inside message" if byte >= 0x80

      pending << byte
    end

    next unless message_complete?(pending, needed)

    messages << parse_single(pending, normalize_note_on_zero: normalize_note_on_zero)
    pending = []
    needed = nil
  end

  raise_incomplete!(pending, needed) unless pending.empty?

  messages
end