Add nim impl

4 files changed, 349 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..705d80c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/music
\ 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..0ad3e3f
--- /dev/null
+++ b/music.nim
@@ -0,0 +1,273 @@
+import musiclib
+
+# Number of times to sample each second
+let bitrate = 44100
+
+let intro = [
+    n(1,3,3),
+    n(1,3,7),
+    n(1,3,10),
+    n(6,4,2),
+
+    n(1,3,1),
+    n(1,3,5),
+    n(1,3,8),
+    n(3,4,0),
+
+    n(1,2,11),
+    n(1,3,3),
+    n(1,3,6),
+    n(3,3,10),
+
+    n(1,2,8),
+    n(1,3,0),
+    n(1,3,3),
+    n(8,3,7),
+]
+
+let melody = [
+    n(1,3,3),
+    n(1,3,7),
+    n(1,3,10),
+    n(1,4,2),
+    n(1,4,3),
+    n(1,4,7),
+    n(2,4,8),
+
+    n(1,3,1),
+    n(1,3,5),
+    n(1,3,8),
+    n(1,4,0),
+    n(1,4,1),
+    n(1,4,5),
+    n(2,4,8),
+
+    n(1,3,3),
+    n(1,3,7),
+    n(1,3,10),
+    n(1,4,2),
+    n(1,4,3),
+    n(1,4,10),
+    n(2,4,3),
+
+    n(1,3,1),
+    n(1,3,5),
+    n(1,3,8),
+    n(1,4,0),
+    n(1,4,10),
+    n(1,4,8),
+    n(2,4,10),
+
+
+    n(1,3,3),
+    n(1,3,7),
+    n(1,3,10),
+    n(1,4,2),
+    n(1,4,3),
+    n(1,4,7),
+    n(2,4,8),
+
+    n(1,3,1),
+    n(1,3,5),
+    n(1,3,8),
+    n(1,4,0),
+    n(1,4,1),
+    n(1,4,5),
+    n(2,4,1),
+
+    n(1,3,3),
+    n(1,3,7),
+    n(1,3,10),
+    n(1,4,2),
+    n(1,4,3),
+    n(1,4,10),
+    n(1,4,8),
+    n(1,4,7),
+
+    n(1,3,1),
+    n(1,3,5),
+    n(1,3,8),
+    n(1,4,0),
+    n(1,4,10),
+    n(1,4,8),
+    n(2,4,10),
+]
+
+let bass = [
+    n(1,1,3),
+    n(1,1,10),
+    n(1,1,1),
+    n(1,1,8),
+    n(1,1,3),
+    n(1,2,3),
+    n(1,1,1),
+    n(1,1,10),
+]
+
+let melody2 = [
+    n(1,0,0),
+    n(1,5,10),
+    n(1,5,8),
+    n(1,5,7),
+    n(1,5,8),
+    n(3,5,7,2),
+
+    n(1,5,3),
+    n(1,4,10),
+    n(6,5,1,2),
+
+    n(1/2,5,0,2),
+    n(1/2,5,1,2),
+    n(3,5,3,2),
+    n(1/2,5,10,2),
+    n(7/2,5,3,2),
+
+    n(8,0,0),
+
+    n(1,0,0),
+    n(1,5,3),
+    n(1,5,10),
+    n(1,5,10),
+    n(4/3,5,10),
+    n(4/3,5,8),
+    n(4/3,5,7),
+
+    n(1,0,0),
+    n(1,5,1),
+    n(1,5,8),
+    n(1,5,8),
+    n(4/3,5,8),
+    n(4/3,5,8),
+    n(4/3,5,10),
+
+    n(8,0,0),
+
+    n(1,0,0),
+    n(5,5,3,2),
+    n(2,5,10,2),
+]
+
+let melody3 = [
+    n(1,0,0),
+    n(1,5,10),
+    n(1/2,5,8,2/3),
+    n(1/2,5,7,2/3),
+    n(1/4,5,8,1/2),
+    n(1/4,5,7,1/2),
+    n(1/4,5,8,1/2),
+    n(1/4,5,7,1/2),
+    n(1,5,8),
+    n(3,5,7,2),
+
+    n(1,5,3),
+    n(1,4,10),
+    n(1,5,1),
+    n(5,5,7,2),
+
+    n(1/2,5,7),
+    n(1/2,5,10),
+    n(1/4,5,7),
+    n(1/4,5,10),
+    n(1/4,5,7),
+    n(1/4,5,10),
+    n(1,6,3),
+    n(2,5,3,2),
+    n(1/2,6,3),
+    n(5/2,5,3,2),
+
+    n(1/2,5,10),
+    n(1/2,5,8),
+    n(1/2,5,7),
+    n(1/2,5,8),
+    n(1/2,5,7),
+    n(1/2,5,3),
+    n(1/2,4,10),
+    n(1/2,5,1),
+    n(1/2,5,0),
+    n(1/2,4,10),
+    n(1/2,4,8),
+    n(1/2,4,10),
+    n(1/2,5,3),
+    n(1/2,5,7),
+    n(1/2,5,3),
+    n(1/2,5,10),
+
+    n(4/3,5,7),
+    n(4/3,6,3),
+    n(4/3,6,3),
+    n(4/3,6,2),
+    n(4/3,5,10),
+    n(4/3,5,7),
+
+    n(3,5,5),
+    n(2,5,7),
+    n(2,5,8),
+    n(1,6,1),
+
+    n(1,5,3),
+    n(1,5,5),
+    n(2,5,7),
+    n(1,5,3),
+    n(1,5,8),
+    n(2,5,10),
+
+    n(3/2,6,0),
+    n(3/2,6,1),
+    n(5,6,3,2),
+]
+
+let outro = [
+    n(1,3,3),
+    n(1,3,7),
+    n(1,3,10),
+    n(1,4,2),
+    n(1,4,3),
+    n(1,4,7),
+    n(2,4,8),
+
+    n(1,3,1),
+    n(1,3,5),
+    n(1,3,8),
+    n(1,4,0),
+    n(1,4,1),
+    n(1,4,5),
+    n(2,4,8),
+
+    n(1,2,11),
+    n(1,3,3),
+    n(1,3,6),
+    n(1,3,10),
+    n(1.5,3,11),
+    n(1.5,4,3),
+    n(3,4,8),
+
+    n(1.5,2,8),
+    n(1.5,3,0),
+    n(2,3,3),
+    n(16,3,7,2),
+]
+
+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, gain=1.5)
+music.process(bass, 32, gain=1.5)
+music.process(melody, 40, 4)
+music.process(melody2, 40, 4)
+music.process(bass, 40, gain=1.5)
+music.process(bass, 48, gain=1.5)
+music.process(melody, 56, 4)
+music.process(melody3, 56, 4)
+music.process(bass, 56, gain=1.5)
+music.process(bass, 64, gain=1.5)
+music.process(outro, 72, 4)
+music.sort()
+
+# 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..7050dd3
--- /dev/null
+++ b/musiclib.nim
@@ -0,0 +1,68 @@
+import std/[algorithm, math, sugar]
+
+type Note* = tuple
+    len: float
+    octave: float
+    step: float
+    vol: float
+
+func n*(a, b, c, d: float = 1): Note =
+    (a, b, c, d)
+
+type ProcessedNote* = tuple
+    start: float
+    `end`: float
+    octave: float
+    step: float
+    vol: float
+
+func process*(music: var seq[ProcessedNote], notes: openArray[Note]; m_start: float, speed: float=1, gain:float = 1) =
+    ## Adds a list of notes to the music list
+    var start = m_start
+    var t = start
+    for note in notes:
+        let vol = note[3]
+        start = min(t, t + note[0] / speed)
+        let `end` = max(t, t + note[0] / speed)
+        music &= ((start, `end`, note[1], note[2], vol * gain))
+        t = `end`
+
+func bisect(music: openArray[ProcessedNote], x: (float, float)): int =
+    ## Return the index where to insert item `x` in list `music`, assuming `music` is sorted.
+    music.lowerBound(x, (m, key) => cmp((m[0], m[1]), key))
+
+
+func freq(octave, step: float): float =
+    ## Returns the frequency of a note
+    55 * pow(2, (octave + step / 12 - 1))
+
+func tone(f, t: float): float =
+    ## Returns the intensity of a tone of frequency f sampled at time t
+    # 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
+    var Y = 0.6 * math.sin(w * t) * math.exp(-0.001 * w * t)
+    Y += 0.2 * math.sin(2 * w * t) * math.exp(-0.001 * w * t)
+    Y += 0.05 * math.sin(3 * w * t) * math.exp(-0.001 * w * t)
+    Y += Y * Y * Y
+    Y *= 1 + 16 * t * math.exp(-6 * t)
+    Y
+
+const bias: float = pow(2.0, 28.0)
+func at*(music: openArray[ProcessedNote], t: float): int32 =
+    ## Returns the total intensity of music sampled at time t
+    let i: int = music.bisect((t, pow(2.0, 31.0)))
+    # This is actually pretty efficient ngl
+    # Because people usually don't have that many overlapping notes
+    var ret: float = 0
+    # this `32` is flaky
+    # maybe some notes are longer?
+    for j in (max(i - 32, 0) ..< i):
+        let m = music[j]
+        if m[0] + m[1] > t:
+            ret += m[4] * tone(freq(m[2], m[3]), t - m[0])
+    int32(ret * bias)