Merge pull request 'Nim port' (#1) from iacore/Lambeat:main into main

Reviewed-on: https://git.exozy.me/a/Lambeat/pulls/1

4 files changed, 424 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..37c3b88
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+/music
+/music.s32
\ No newline at end of file
diff --git a/README.md b/README.md
index 7a50d67..eb1259f 100644
--- a/README.md
+++ b/README.md
@@ -5,3 +5,10 @@ Lambeat is a new way to make music using functional programming. It's heavily in
 First, install [Sox](https://sox.sourceforge.net/) and clone this repo. Write some music in `music.scm`. Enjoy your music with `guile --fresh-auto-compile lambeat.scm | play -r 8000 -t s16 -`!
 
 For the Python version, use `pypy3 music.py | play -r 44100 -t s32 -` to listen and `pypy3 music.py | sox -r 44100 -t s32 - example.ogg` to save to a file.
+
+For the nim version
+```
+nim c --mm:orc -d:release music.nim
+./music > music.s32
+play -r 44100 -t s32 music.s32
+```
diff --git a/music.nim b/music.nim
new file mode 100644
index 0000000..2ad0e3f
--- /dev/null
+++ b/music.nim
@@ -0,0 +1,340 @@
+import musiclib, std/[math, sugar]
+
+# Number of times to sample each second
+const bitrate = 44100
+
+func osc_weird_pluck*(f, t: float): float =
+  # I got this as a bug
+  let w = 2 * PI * f
+  let wxt = w * t
+  let exp_swxt = math.exp(-0.001 * wxt)
+  let y0 = 0.6 * math.sin(wxt)
+  let y1 = 0.2 * math.sin(2 * wxt)
+  let y2 = 0.05 * math.sin(3 * wxt)
+  let y3 = (y0 + y1 + y2) * exp_swxt
+  let y4 = (1+y3)*y3*y3 # this line is different
+  y4 * (1 + 16 * t * math.exp(-6 * t))
+
+func osc_piano*(f, t: float): float =
+  ## Returns the intensity of a tone of frequency f sampled at time t
+  ## t starts at 0 (note start)
+  # https://dsp.stackexchange.com/questions/46598/mathematical-equation-for-the-sound-wave-that-a-piano-makes
+  # https://youtu.be/ogFAHvYatWs?t=254
+  # return int(2**13*(1+square(t, 440*2**(math.floor(5*t)/12))))
+  # Y = sum([math.sin(2 * i * math.pi * t * f) * math.exp(-0.0004 * 2 * math.pi * t * f) / 2**i for i in range(1, 4)])
+  # Y += Y * Y * Y
+  # Y *= 1 + 16 * t * math.exp(-6 * t)
+  let w = 2 * PI * f
+  let ewt = math.exp(-0.001 * w * t)
+  var Y = 0.6 * math.sin(w * t) * ewt +
+        0.2 * math.sin(2 * w * t) * ewt +
+        0.05 * math.sin(3 * w * t) * ewt
+  
+  let Y2 = Y * (Y * Y + 1)
+  Y2 * (1 + 16 * t * math.exp(-6 * t))
+
+func osc_pulse*(f, t: float, phasedrift: float = 0.0): float =
+  let doublewidth = 1.0 / f
+  let width = doublewidth / 2
+  let phase: float = (t + doublewidth * phasedrift) mod doublewidth
+  if phase < width: 1.0 else: -1.0
+
+func osc_saw*(f,t:float, phasedrift: float = 0.0):float =
+  let doublewidth = 1.0 / f
+  let width = doublewidth / 2
+  let phase: float = (t + doublewidth * phasedrift) mod doublewidth
+  if phase < width:
+    -1.0 + 2.0 * phase / width
+  else:
+    1.0 - 2.0 * (phase - width) / (1.0 - width)
+
+func freq*(octave, step: float): float =
+  ## Returns the frequency of a note
+  55 * pow(2, (octave + step / 12 - 1))
+
+var osc: OscFn = (f, t: float) => 0.0
+
+proc p*(len, octave, step, vol: float = 1): Note =
+  ## Note helper constructor
+  (len, freq(octave, step), vol, osc)
+
+#------- song region -------
+
+const GAIN_NORMAL = 0.22
+
+osc = (f, t: float) => osc_piano(f, t) * GAIN_NORMAL
+
+let intro = [
+    p(1, 3, 3),
+    p(1, 3, 7),
+    p(1, 3, 10),
+    p(6, 4, 2),
+
+    p(1, 3, 1),
+    p(1, 3, 5),
+    p(1, 3, 8),
+    p(3, 4, 0),
+
+    p(1, 2, 11),
+    p(1, 3, 3),
+    p(1, 3, 6),
+    p(3, 3, 10),
+
+    p(1, 2, 8),
+    p(1, 3, 0),
+    p(1, 3, 3),
+    p(8, 3, 7),
+]
+
+let outro = [
+    p(1, 3, 3),
+    p(1, 3, 7),
+    p(1, 3, 10),
+    p(1, 4, 2),
+    p(1, 4, 3),
+    p(1, 4, 7),
+    p(2, 4, 8),
+
+    p(1, 3, 1),
+    p(1, 3, 5),
+    p(1, 3, 8),
+    p(1, 4, 0),
+    p(1, 4, 1),
+    p(1, 4, 5),
+    p(2, 4, 8),
+
+    p(1, 2, 11),
+    p(1, 3, 3),
+    p(1, 3, 6),
+    p(1, 3, 10),
+    p(1.5, 3, 11),
+    p(1.5, 4, 3),
+    p(3, 4, 8),
+
+    p(1.5, 2, 8),
+    p(1.5, 3, 0),
+    p(2, 3, 3),
+    p(16, 3, 7, 2),
+]
+
+let melody = [
+    p(1, 3, 3),
+    p(1, 3, 7),
+    p(1, 3, 10),
+    p(1, 4, 2),
+    p(1, 4, 3),
+    p(1, 4, 7),
+    p(2, 4, 8),
+
+    p(1, 3, 1),
+    p(1, 3, 5),
+    p(1, 3, 8),
+    p(1, 4, 0),
+    p(1, 4, 1),
+    p(1, 4, 5),
+    p(2, 4, 8),
+
+    p(1, 3, 3),
+    p(1, 3, 7),
+    p(1, 3, 10),
+    p(1, 4, 2),
+    p(1, 4, 3),
+    p(1, 4, 10),
+    p(2, 4, 3),
+
+    p(1, 3, 1),
+    p(1, 3, 5),
+    p(1, 3, 8),
+    p(1, 4, 0),
+    p(1, 4, 10),
+    p(1, 4, 8),
+    p(2, 4, 10),
+
+
+    p(1, 3, 3),
+    p(1, 3, 7),
+    p(1, 3, 10),
+    p(1, 4, 2),
+    p(1, 4, 3),
+    p(1, 4, 7),
+    p(2, 4, 8),
+
+    p(1, 3, 1),
+    p(1, 3, 5),
+    p(1, 3, 8),
+    p(1, 4, 0),
+    p(1, 4, 1),
+    p(1, 4, 5),
+    p(2, 4, 1),
+
+    p(1, 3, 3),
+    p(1, 3, 7),
+    p(1, 3, 10),
+    p(1, 4, 2),
+    p(1, 4, 3),
+    p(1, 4, 10),
+    p(1, 4, 8),
+    p(1, 4, 7),
+
+    p(1, 3, 1),
+    p(1, 3, 5),
+    p(1, 3, 8),
+    p(1, 4, 0),
+    p(1, 4, 10),
+    p(1, 4, 8),
+    p(2, 4, 10),
+]
+
+osc = (f, t: float) => osc_weird_pluck(f, t) * GAIN_NORMAL
+
+let melody2 = [
+    p(1, 0, 0),
+    p(1, 5, 10),
+    p(1, 5, 8),
+    p(1, 5, 7),
+    p(1, 5, 8),
+    p(3, 5, 7, 2),
+
+    p(1, 5, 3),
+    p(1, 4, 10),
+    p(6, 5, 1, 2),
+
+    p(1/2, 5, 0, 2),
+    p(1/2, 5, 1, 2),
+    p(3, 5, 3, 2),
+    p(1/2, 5, 10, 2),
+    p(7/2, 5, 3, 2),
+
+    p(8, 0, 0),
+
+    p(1, 0, 0),
+    p(1, 5, 3),
+    p(1, 5, 10),
+    p(1, 5, 10),
+    p(4/3, 5, 10),
+    p(4/3, 5, 8),
+    p(4/3, 5, 7),
+
+    p(1, 0, 0),
+    p(1, 5, 1),
+    p(1, 5, 8),
+    p(1, 5, 8),
+    p(4/3, 5, 8),
+    p(4/3, 5, 8),
+    p(4/3, 5, 10),
+
+    p(8, 0, 0),
+
+    p(1, 0, 0),
+    p(5, 5, 3, 2),
+    p(2, 5, 10, 2),
+]
+
+let melody3 = [
+    p(1, 0, 0),
+    p(1, 5, 10),
+    p(1/2, 5, 8, 2/3),
+    p(1/2, 5, 7, 2/3),
+    p(1/4, 5, 8, 1/2),
+    p(1/4, 5, 7, 1/2),
+    p(1/4, 5, 8, 1/2),
+    p(1/4, 5, 7, 1/2),
+    p(1, 5, 8),
+    p(3, 5, 7, 2),
+
+    p(1, 5, 3),
+    p(1, 4, 10),
+    p(1, 5, 1),
+    p(5, 5, 7, 2),
+
+    p(1/2, 5, 7),
+    p(1/2, 5, 10),
+    p(1/4, 5, 7),
+    p(1/4, 5, 10),
+    p(1/4, 5, 7),
+    p(1/4, 5, 10),
+    p(1, 6, 3),
+    p(2, 5, 3, 2),
+    p(1/2, 6, 3),
+    p(5/2, 5, 3, 2),
+
+    p(1/2, 5, 10),
+    p(1/2, 5, 8),
+    p(1/2, 5, 7),
+    p(1/2, 5, 8),
+    p(1/2, 5, 7),
+    p(1/2, 5, 3),
+    p(1/2, 4, 10),
+    p(1/2, 5, 1),
+    p(1/2, 5, 0),
+    p(1/2, 4, 10),
+    p(1/2, 4, 8),
+    p(1/2, 4, 10),
+    p(1/2, 5, 3),
+    p(1/2, 5, 7),
+    p(1/2, 5, 3),
+    p(1/2, 5, 10),
+
+    p(4/3, 5, 7),
+    p(4/3, 6, 3),
+    p(4/3, 6, 3),
+    p(4/3, 6, 2),
+    p(4/3, 5, 10),
+    p(4/3, 5, 7),
+
+    p(3, 5, 5),
+    p(2, 5, 7),
+    p(2, 5, 8),
+    p(1, 6, 1),
+
+    p(1, 5, 3),
+    p(1, 5, 5),
+    p(2, 5, 7),
+    p(1, 5, 3),
+    p(1, 5, 8),
+    p(2, 5, 10),
+
+    p(3/2, 6, 0),
+    p(3/2, 6, 1),
+    p(5, 6, 3, 2),
+]
+
+# clip length to 1 second
+osc = (f, t: float) => (if t > 1: 0.0 else:
+  (osc_saw(f, t) * GAIN_NORMAL * 0.06) + (osc_pulse(f, t) * GAIN_NORMAL * 0.3))
+
+let bass = [
+    p(1, 1, 3),
+    p(1, 1, 10),
+    p(1, 1, 1),
+    p(1, 1, 8),
+    p(1, 1, 3),
+    p(1, 2, 3),
+    p(1, 1, 1),
+    p(1, 1, 10),
+]
+
+from std/algorithm import sort
+
+# Process all lists of notes
+var music: seq[ProcessedNote] = @[]
+music.process(intro, 0, 4)
+music.process(melody, 8, 4)
+music.process(melody, 24, 4)
+music.process(bass, 24)
+music.process(bass, 32)
+music.process(melody, 40, 4)
+music.process(melody2, 40, 4)
+music.process(bass, 40)
+music.process(bass, 48)
+music.process(melody, 56, 4)
+music.process(melody3, 56, 4)
+music.process(bass, 56)
+music.process(bass, 64)
+music.process(outro, 72, 4)
+music.sortByStart()
+
+# Print out music encoded in s16 to standard output
+for i in (0 * bitrate ..< 84 * bitrate):
+  let bytes = cast[array[4, uint8]](music.at(i / bitrate))
+  doAssert 4 == stdout.writeBytes(bytes, 0, 4)
diff --git a/musiclib.nim b/musiclib.nim
new file mode 100644
index 0000000..c21cb95
--- /dev/null
+++ b/musiclib.nim
@@ -0,0 +1,75 @@
+import std/[algorithm, math, sugar, strformat, logging]
+
+type
+    OscFn* = proc (f: float, t: float): float
+
+    Note* = tuple
+        len: float ## seconds
+        freq: float
+        vol: float
+        osc: OscFn
+
+    ProcessedNote* = tuple
+        start: float ## absolute time in seconds
+        stop: float  ## absolute time in seconds
+        freq: float
+        vol: float
+        osc: OscFn
+
+const HACK_LONGEST_NOTE = 16.0
+
+func process*(music: var seq[ProcessedNote], notes: openArray[Note]; start_init: float, speed: float=1) =
+    ## Adds a list of notes to the music list
+    ##
+    ## `notes`  sequence of notes with no rests in between
+    var start = start_init
+    var t = start
+    for note in notes:
+        assert note.len >= 0.0
+        assert note.len <= HACK_LONGEST_NOTE, &"note too long: {note.len}"
+        start = t
+        let stop = t + note.len / speed
+        music &= (start, stop, note.freq, note.vol, note.osc)
+        t = stop
+
+func sortByStart*(music: var seq[ProcessedNote]) =
+    music.sort((a, b) => cmp(a.start, b.start))
+
+func bisect(music: openArray[ProcessedNote], x: float): int =
+    ## Return the index where to insert item `x` in list `music`
+    ## 
+    ## assumes `music` is sorted by `.start`
+
+    music.lowerBound(x, (m, key) => cmp(m.start, key))
+
+const GAIN_BIAS: float = pow(2.0, 31.0)
+
+proc at*(music: openArray[ProcessedNote], t: float): int32 =
+    ## Returns the total intensity of music sampled at time t
+    ## 
+    ## assumes `music` is sorted by `.start`
+
+    var i: int = music.bisect(t) - 1    
+    
+    var ret: float = 0
+
+    while i >= 0:
+        let m = music[i]
+        assert m.start <= t
+        if m.start + HACK_LONGEST_NOTE < t:
+            break
+        else:
+            ret += m.vol * m.osc(m.freq, t - m.start)
+        i -= 1
+
+    ret *= GAIN_BIAS
+    
+    # clip sample
+    if ret >= int32.high.float:
+        warn(&"audio clipping at t={t}")
+        int32.high
+    elif ret <= int32.low.float:
+        warn(&"audio clipping at t={t}")
+        int32.low
+    else:
+        int32(ret)