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Task/Pi/Nim/pi.nim

@@ -0,0 +1,50 @@
+import strutils, unsigned, bigints
+
+var
+  tmp1, tmp2, tmp3, acc, k, dd = initBigInt(0)
+  den, num, k2 = initBigInt(1)
+
+proc extractDigit(): int32 =
+  if num > acc:
+    return -1
+
+  tmp3 = num shl 1
+  tmp3 += num
+  tmp3 += acc
+  tmp2 = tmp3 mod den
+  tmp1 = tmp3 div den
+  tmp2 += num
+
+  if tmp2 >= den:
+    return -1
+
+  result = int32(tmp1.limbs[0])
+
+proc eliminateDigit(d: int32) =
+  acc -= den * d
+  acc *= 10
+  num *= 10
+
+proc nextTerm() =
+  k += 1
+  k2 += 2
+  tmp1 = num shl 1
+  acc += tmp1
+  acc *= k2
+  den *= k2
+  num *= k
+
+var i = 0
+
+while true:
+  var d: int32 = -1
+  while d < 0:
+    nextTerm()
+    d = extractDigit()
+
+  stdout.write chr(ord('0') + d)
+  inc i
+  if i == 40:
+    echo ""
+    i = 0
+  eliminateDigit d