switch to fastrand (not actually any faster)

combinators.nim

@@ -1,5 +1,5 @@
 import algorithm, random, sugar
-import fixedseq, game
+import fastrand, fixedseq, game
 
 
 proc nextPermutation(x: var FixedSeq): bool =
@@ -93,4 +93,4 @@ proc randomFuture*(dice: FixedSeq, r: var Rand): FixedSeq[5, Die, int8] =
   result.initFixedSeq
   let order = dice.dup(shuffle(r))
   for i, color in order:
-    result.add((color, r.rand(1..3)))
+    result.add((color, r.fastRand(1..3)))

config.nims

@@ -2,4 +2,4 @@
 --d: release
 --opt: speed
 --passC: -flto
---passL: -flto
+--passL: -flto

fastrand.nim

@@ -0,0 +1,74 @@
+import random, math
+import times, std/monotimes, strformat, strutils
+
+
+proc formatNum(n: SomeNumber): string =
+  let s = $(n.round)
+  let t = s[0 .. s.len - 3]
+  var count = 1
+  for i in countdown(t.high, 0):
+    result.insert($t[i], 0)
+    if count mod 3 == 0 and i != 0:
+      result.insert(",", 0)
+    count += 1
+
+
+proc formatRate(n: Natural, d: Duration): string =
+  result = formatNum(1_000_000'f64 * n.float64 / d.inMicroseconds.float64)
+
+
+const upperBound = uint64(uint32.high)
+
+
+proc fastRand*[T: Natural](r: var Rand, x: T): T =
+  # Nim ranges are usually inclusive, but this algorithm is exclusive
+  let x = x.uint64 + 1
+  let num = if x <= upperBound:
+    ((r.next shr 32) * x.uint64) shr 32
+  else:
+    r.next mod x.uint64
+  result = T(num)
+
+
+proc fastRand*(r: var Rand; x, y: Natural): Natural =
+  let lim = (y - x)
+  result = fastRand(r, lim) + x
+
+
+proc fastRand*[T](r: var Rand, slice: HSlice[T, T]): T =
+  let n = fastRand(r, slice.a.Natural, slice.b.Natural)
+  result = T(n)
+
+
+proc testFastRand(num = 1_000_000_000): Duration =
+  var r = initRand(rand(int64))
+  let start = getMonoTime()
+  for i in 1 .. num:
+    discard r.fastRand(5)
+  result = getMonoTime() - start
+  # echo "fastrand execution rate: ",  1000 * num / dur.inMilliseconds.int, " generated per second."
+
+
+proc testStdRand(num = 1_000_000_000): Duration =
+  var r = initRand(rand(int64))
+  let start = getMonoTime()
+  for i in 1 .. num:
+    discard r.rand(4)
+  result = getMonoTime() - start
+  # echo "std rand execution rate: ", 1000 * num / dur.inMilliseconds.int, " generated per second."
+
+
+when isMainModule:
+  randomize()
+  var r = initRand(rand(int64))
+  let runs = 100_000_000
+  var totals: array[5..9, int]
+  for i in 1 .. runs:
+    let n = r.fastRand(5..9)
+    totals[n] += 1
+  echo totals
+
+  # let fr = testFastRand(runs)
+  # echo "fastrand execution rate: ", formatNum(1_000_000 * runs / fr.inMicroseconds.int)
+  # let sr = testStdRand(runs)
+  # echo "standard execution rate: ", formatNum(1_000_000 * runs / sr.inMicroseconds.int)

game.nim

@@ -57,7 +57,7 @@ type
     squares*: array[1..16, Square]
     camels*: array[Color, range[1..16]]
     diceRolled*: array[Color, bool]
-    winner*: Option[Color]
+    leader*: Option[Color]
     gameOver*: bool
     initialized: bool
 
@@ -66,10 +66,6 @@ type
 template `[]`*[T](b: var Board, idx: T): var Square =
   b.squares[idx]
 
-# apparently we need separate ones for mutable and non-mutable
-template `[]`*[T](b: Board, idx: T): Square =
-  b.squares[idx]
-
 
 proc hash*(b: Board): Hash =
   var h: Hash = 0
@@ -91,11 +87,6 @@ proc init*(b: var Board) =
   b.initialized = true
 
 
-proc leader*(b: Board): Color =
-  let leadSquare = max(b.camels)
-  result = b[leadSquare].camels[^1]
-
-
 proc display*(b: Board, start, stop: int) =
   for i in start..stop:
     let sq = b.squares[i]
@@ -117,6 +108,9 @@ proc setState*(b: var Board;
   for (tile, dest) in tiles:
     b[dest].tile = some(tile)
 
+  let leadCamel = b[max(b.camels)].camels[^1] # top camel in the last currently-occupied space
+  b.leader = some(leadCamel)
+
 
 proc diceRemaining*(b: Board): ColorStack =
   result.initFixedSeq
@@ -125,7 +119,7 @@ proc diceRemaining*(b: Board): ColorStack =
 
 
 proc resetDice*(b: var Board) =
-  for c in Color:
+  for c, rolled in b.diceRolled:
     b.diceRolled[c] = false
 
 
@@ -136,7 +130,7 @@ proc advance*(b: var Board, die: Die) =
   var endPos = startPos + roll
   
   if endPos > 16: # camel has passed the finish line
-    b.winner = some(b[startPos].camels[^1])
+    b.leader = some(b[startPos].camels[^1])
     b.gameOver = true
     return
 
@@ -160,4 +154,8 @@ proc advance*(b: var Board, die: Die) =
     for i in (dstPrevHigh + 1) .. b[endPos].camels.high:
       b.camels[b[endPos].camels[i]] = endPos
   
+  # if we are stacking on or moving past the previous leader
+  if endPos >= b.camels[b.leader.get]:
+    b.leader = some(b[endPos].camels[^1])
+  
   b.diceRolled[color] = true

simulation.nim

@@ -52,7 +52,7 @@ iterator legEndStates(b: Board): Board =
 
 proc getLegScores*(b: Board): ScoreSet =
   for prediction in b.legEndStates:
-    inc result[prediction.winner.get]
+    inc result[prediction.leader.get]
 
 
 # =====================
@@ -65,7 +65,7 @@ proc randomGame*(b: Board, r: var Rand): Color =
     for roll in randomFuture(projection.diceRemaining, r):
       projection.advance(roll)
       if projection.gameOver:
-        return projection.winner.get
+        return projection.leader.get
     projection.resetDice()