format nim

slight performance improvement

music.nim

@@ -26,9 +26,11 @@ func osc_piano*(f, t: float): float =
   # 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
+  var Y = (
+    0.6 * math.sin(w * t) +
+    0.2 * math.sin(2 * w * t) +
+    0.05 * math.sin(3 * w * t)
+  ) * ewt
   
   let Y2 = Y * (Y * Y + 1)
   Y2 * (1 + 16 * t * math.exp(-6 * t))

musiclib.nim

@@ -1,75 +1,77 @@
 import std/[algorithm, math, sugar, strformat, logging]
 
 type
-    OscFn* = proc (f: float, t: float): float
+  OscFn* = proc (f: float, t: float): float {.gcsafe.}
+  Note* = tuple
+    len: float ## seconds
+    freq: float
+    vol: float
+    osc: OscFn
 
-    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
+  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 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))
+  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`
+  ## 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))
+  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`
+  ## 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
+  var i: int = music.bisect(t) - 1
 
-    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
+  var notes: seq[ProcessedNote] = @[]
+  while i >= 0:
+    let m = music[i]
+    assert m.start <= t
+    if m.start + HACK_LONGEST_NOTE < t:
+      break
     else:
-        int32(ret)
+      notes &= m
+    i -= 1
+
+  var sample_sum: float = 0
+  for m in notes:
+    sample_sum += (m.vol * m.osc(m.freq, t - m.start))
+
+  let ret = sample_sum * 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)