# Thunderstruck - Angus Young and Malcolm Young (AC/DC, The Razors Edge, 1990) - https://lab.glossema.dev/play/thunderstruck/code
# It plays the notes of https://lab.glossema.dev/play/thunderstruck, tone for tone.
# The guitar riff that opens the record, one octave above the recording, at 112 ms a sixteenth.
# One guitar, one note at a time: a fretted line on the B string, and the open B string
# between every two of its notes, so that one line is heard as two voices.
# The two opening figures play twice, two bars each; then the descent, one phrase of two bars, six times.
# The last B is held as the arrangement's ending, where the record's riff runs on.

{
  # Hz for each pitch: the riff one octave above the record, and the low B of the ending
  :local pitch {"B3"=247; "B4"=494; "D#5"=622; "E5"=659; "F#5"=740; "G5"=784; "G#5"=831; "A5"=880; "B5"=988}

  # The riff: each fretted note fills its sixteenth, and the open B answers it, cut short.
  # A bar holds eight fretted notes; a figure repeats until its bars are full.
  :local riff do={
    :for pass from=1 to=((8 * $bars) / [:len $notes]) do={
      :foreach note in=$notes do={
        :beep frequency=($pitch->$note) length=107ms
        :delay 112ms
        :beep frequency=($pitch->"B4") length=85ms
        :delay 112ms
      }
    }
  }

  # The fretted notes of each part: G natural in the E and G figure, G sharp in the descent
  :local openDF {"D#5";"F#5"}
  :local openEG {"E5";"G5"}
  :local descent {"B5";"A5";"G#5";"A5";"G#5";"F#5";"G#5";"E5";"F#5";"D#5";"E5";"D#5";"E5";"D#5";"E5";"D#5"}

  :put "Intro"
  # The pickup: the open B alone
  :beep frequency=($pitch->"B4") length=85ms
  :delay 112ms
  # D sharp and F sharp for two bars, E and G for two, all four bars twice
  :for pass from=1 to=2 do={
    $riff notes=$openDF bars=2 pitch=$pitch
    $riff notes=$openEG bars=2 pitch=$pitch
  }

  :put "The descent"
  # One phrase of two bars, from the top B down to D sharp, six times
  :for pass from=1 to=6 do={
    $riff notes=$descent bars=2 pitch=$pitch
  }

  # The arrival: a bass B, then the top B that would open a seventh descent, held
  :beep frequency=($pitch->"B3") length=30ms
  :delay 35ms
  :beep frequency=($pitch->"B5") length=1500ms
  :delay 1500ms
}