Class: RubyTDMS::Objects::Channel

Inherits:
Base
  • Object
show all
Defined in:
lib/ruby_tdms/objects/channel.rb

Instance Attribute Summary collapse

Attributes inherited from Base

#path, #properties, #segment, #stream

Instance Method Summary collapse

Constructor Details

#initialize(path, document, segment) ⇒ Channel

Returns a new instance of Channel.



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# File 'lib/ruby_tdms/objects/channel.rb', line 11

def initialize(path, document, segment)
	super
	@chunk_offsets = []
	@value_count = 0
end

Instance Attribute Details

#chunk_length ⇒ Object (readonly)

Returns the value of attribute chunk_length.



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# File 'lib/ruby_tdms/objects/channel.rb', line 8

def chunk_length
  @chunk_length
end

#chunk_offsets ⇒ Object (readonly)

Returns the value of attribute chunk_offsets.



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# File 'lib/ruby_tdms/objects/channel.rb', line 8

def chunk_offsets
  @chunk_offsets
end

#chunk_value_count ⇒ Object (readonly)

Returns the value of attribute chunk_value_count.



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# File 'lib/ruby_tdms/objects/channel.rb', line 8

def chunk_value_count
  @chunk_value_count
end

#data_length ⇒ Object (readonly)

Returns the value of attribute data_length.



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# File 'lib/ruby_tdms/objects/channel.rb', line 8

def data_length
  @data_length
end

#data_type ⇒ Object (readonly)

Returns the value of attribute data_type.



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# File 'lib/ruby_tdms/objects/channel.rb', line 8

def data_type
  @data_type
end

#data_type_id ⇒ Object (readonly)

Returns the value of attribute data_type_id.



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# File 'lib/ruby_tdms/objects/channel.rb', line 8

def data_type_id
  @data_type_id
end

#dimensions ⇒ Object (readonly)

Returns the value of attribute dimensions.



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# File 'lib/ruby_tdms/objects/channel.rb', line 8

def dimensions
  @dimensions
end

#raw_data_offset ⇒ Object (readonly)

Returns the value of attribute raw_data_offset.



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# File 'lib/ruby_tdms/objects/channel.rb', line 8

def raw_data_offset
  @raw_data_offset
end

#value_count ⇒ Object (readonly)

Returns the value of attribute value_count.



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# File 'lib/ruby_tdms/objects/channel.rb', line 8

def value_count
  @value_count
end

#value_offset ⇒ Object (readonly)

Returns the value of attribute value_offset.



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# File 'lib/ruby_tdms/objects/channel.rb', line 8

def value_offset
  @value_offset
end

Instance Method Details

#as_json ⇒ Object 



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# File 'lib/ruby_tdms/objects/channel.rb', line 23

def as_json
	super.merge({
		name: name,
		data_type: data_type.name.split('::').last,
		dimensions: dimensions,
		values: values.to_a
	})
end

#calculate_offsets ⇒ Object

After all channels in a segment have been read, we have to determine our raw data starting offset and the offsets for all individual values, based on the number of chunks in the segment as well as whether the segment is interleaved.



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# File 'lib/ruby_tdms/objects/channel.rb', line 67

def calculate_offsets
	previous_channel = nil
	channels = @segment.raw_channels
	me = channels.index self
	previous_channel = channels[me - 1] if me and me > 0

	if @segment.interleaved_data?
		@value_offset = @segment.raw_channels.map(&:data_length).reduce :+
	else
		@value_offset = @data_length
	end

	@raw_data_offset = @segment.raw_data_offset
	if previous_channel
		@raw_data_offset = previous_channel.raw_data_offset
		@raw_data_offset += @segment.interleaved_data? ? previous_channel.data_length : previous_channel.chunk_length
	end

	@segment.chunk_count.times do
		@chunk_offsets << @raw_data_offset + @chunk_offsets.length * @chunk_length
	end
	@value_count = @chunk_value_count * @segment.chunk_count
end

#continue_stream(stream, raw_index, previous_channel) ⇒ Object

When a channel is continued in a new segment, this method is called rather than #parse_stream



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# File 'lib/ruby_tdms/objects/channel.rb', line 51

def continue_stream(stream, raw_index, previous_channel)
	@chunk_value_count = previous_channel.chunk_value_count
	@data_length = previous_channel.data_length
	@data_type = previous_channel.data_type
	@data_type_id = previous_channel.data_type_id
	@dimensions = previous_channel.dimensions

	@chunk_length = @data_length * @dimensions * @chunk_value_count # Size of the data for this channel in a given chunk.

	super stream, previous_channel
end

#name ⇒ Object 



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# File 'lib/ruby_tdms/objects/channel.rb', line 18

def name
	path.to_a.last
end

#parse_stream(stream, raw_index) ⇒ Object

Get all data from the stream to configure ourself with data type, number of values, etc.



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# File 'lib/ruby_tdms/objects/channel.rb', line 34

def parse_stream(stream, raw_index)
	@data_type_id = stream.read_u32
	@dimensions = stream.read_u32
	@chunk_value_count = stream.read_u64

	@data_type = DataTypes.find_by_id @data_type_id
	# Get the data length for variable length types (when DataTypes::LENGTH_IN_BYTES is nil)
	@data_length = @data_type::LENGTH_IN_BYTES || stream.read_u64

	# Chunk length is the same as data length for variable length types
	@chunk_length = @data_type::LENGTH_IN_BYTES.nil? ? @data_length : @data_length * @dimensions * @chunk_value_count # Size of the data for this channel in a given chunk.

	super stream
end

#values ⇒ Object 



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# File 'lib/ruby_tdms/objects/channel.rb', line 92

def values
	@values ||= begin
		klass = if @data_type::LENGTH_IN_BYTES.nil?
			StringChannelEnumerator
		else
			ChannelEnumerator
		end

		klass.new self
	end
end