optimize arithmetics

examples/pi-bench.py

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+#  Copyright 2026 Sergey S. Chernov real.sergeych@gmail.com
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+import time
+from multiprocessing import Process
+
+def piSpigot(iThread, nx):
+    piIter = 0
+    pi = [None] * nx
+    boxes = nx * 10 // 3
+    reminders = [None]*boxes
+    i = 0
+    while i < boxes:
+        reminders[i] = 2
+        i += 1
+    heldDigits = 0
+    i = 0
+    while i < nx:
+        carriedOver = 0
+        sum = 0
+        j = boxes - 1
+        while j >= 0:
+            reminders[j] *= 10
+            sum = reminders[j] + carriedOver
+            quotient = sum // (j * 2 + 1)
+            reminders[j] = sum % (j * 2 + 1)
+            carriedOver = quotient * j
+            j -= 1
+        reminders[0] = sum % 10
+        q = sum // 10
+        if q == 9:
+            heldDigits += 1
+        elif q == 10:
+            q = 0
+            k = 1
+            while k <= heldDigits:
+                replaced = pi[i - k]
+                if replaced == 9:
+                    replaced = 0
+                else:
+                    replaced += 1
+                pi[i - k] = replaced
+                k += 1
+            heldDigits = 1
+        else:
+            heldDigits = 1
+        pi[piIter] = q
+        piIter += 1
+        i += 1
+    res = ""
+    for i in range(len(pi)-8, len(pi), 1):
+        res += str(pi[i])
+    print(str(iThread) + ": " + res)
+
+def createProcesses():
+    THREADS = 1
+    WORK_SIZE = 500
+    print("piBench (python3): THREADS = " + str(THREADS) + ", WORK_SIZE = " + str(WORK_SIZE))
+    pa = []
+    for i in range(THREADS):
+        p = Process(target=piSpigot, args=(i, WORK_SIZE))
+        p.start()
+        pa.append(p)
+    for p in pa:
+        p.join()
+
+if __name__ == "__main__":
+    t1 = time.time()
+    createProcesses()
+    dt = time.time() - t1
+    print("total time: %i ms" % (dt*1000))