class ZXUtils::MusicBox::Envelope

MusicBox Envelope ↑

Instances of this class represent the envelopes applicable to the volume level or the noise pitch.

Attributes

code[R]

A compiled body of the evelope as a binary string.

Public Class Methods

new [counter, delta], ... click to toggle source
new [counter, delta], ..., :loop, ..., [counter, delta]

Creates an instance of the Envelope with the given tuples shaping the envelope.

counter

How many ticks should pass to reach the desired delta: 1 to 255.

delta

A floating point number in the range: from -1 to 1.

:loop

An indicator where to go back when the end of the envelope is being reached. If not present the whole envelope is being repeated.

# File lib/zxutils/music_box/song.rb, line 438
def initialize(*args)
        loop_offset = nil
        bytes = []
        args.each do |arg|
                case arg
                when Array
                        bytes.concat Array(tuple_to_value(*arg))
                when :loop
                        raise ArgumentError, "There's more than one loop marker" unless loop_offset.nil?
                        loop_offset = bytes.length
                else
                        raise ArgumentError, "A tuple of [counter, value] is expected or :loop"
                end
        end
        raise ArgumentError, "Envelope requires at least one tuple argument" if bytes.empty?
        loop_offset = loop_offset.to_i
        raise ArgumentError, "Loop indicator must be placed before at least one argument tuple" if loop_offset == bytes.length
        raise ArgumentError, "Loop offset too large" if loop_offset > 255
        @code = [loop_offset].concat(bytes).pack('c*')
end