Examples: Fix compiling issues and imports, closes #69 (#73)

Author: dlesnoff

examples/elliptic.nim

@@ -1,59 +1,42 @@
-# By Cyther606: http://forum.nimrod-lang.org/t/522
+# By Cyther606: https://forum.nim-lang.org/t/522
 # Adapted from: https://github.com/wobine/blackboard101/blob/master/EllipticCurvesPart4-PrivateKeyToPublicKey.py
-import bigints, math, strutils
+import bigints
+import std/[math, strutils]
 
-proc `^`(base: int; exp: int): BigInt =
-  let base = base.initBigInt
-  var exp = exp
-  result = 1.initBigInt
-  while exp > 0:
-    result *= base
-    dec(exp)
+const
+  one = 1.initBigInt
+  two = 2.initBigInt
+  zero = 0.initBigInt
 
+proc `^`(base: int; exp: int): BigInt = pow(base.initBigInt, exp)
+
+# Specs of the Bitcoin's curve - secp256k1
 let
-  Pcurve: BigInt = 2^256 - 2^32 - 2^9 - 2^8 - 2^7 - 2^6 - 2^4 - 1
-  N = initBigInt("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141", 16)
-  Acurve = 0.initBigInt
-  Bcurve = 7.initBigInt
+  primeCurve: BigInt = 2^256 - 2^32 - 2^9 - 2^8 - 2^7 - 2^6 - 2^4 - one
+  numberPoints = initBigInt("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141", 16)
+  Acurve = zero # with Bcurve = 7, coefficients in the elliptic curve equation y^2 = x^3 + Acurve * x + Bcurve
   Gx = initBigInt("55066263022277343669578718895168534326250603453777594175500187360389116729240")
   Gy = initBigInt("32670510020758816978083085130507043184471273380659243275938904335757337482424")
   Gpoint = (Gx, Gy)
   privKey = initBigInt("A0DC65FFCA799873CBEA0AC274015B9526505DAAAED385155425F7337704883E", 16)
 
-proc modinv(a: BigInt): BigInt =
-  var
-    lm = 1.initBigInt
-    hm = 0.initBigInt
-    lowm = a mod Pcurve
-    highm = Pcurve
-  while lowm > 1:
-    let
-      ratio = highm div lowm
-      nm = hm - (lm * ratio)
-      temp = highm - (lowm * ratio)
-    hm = nm
-    highm = temp
-    swap hm, lm
-    swap highm, lowm
-  result = lm mod Pcurve
-
 proc ecAdd(a: tuple, b: tuple): (BigInt, BigInt) =
   let
-    lamAdd = ((b[1] - a[1]) * modinv(b[0] - a[0])) mod Pcurve
-    x = (lamAdd * lamAdd - a[0] - b[0]) mod Pcurve
-    y = (lamAdd * (a[0] - x) - a[1]) mod Pcurve
+    lamAdd = ((b[1] - a[1]) * invmod((b[0] - a[0]), primeCurve)) mod primeCurve
+    x = (lamAdd * lamAdd - a[0] - b[0]) mod primeCurve
+    y = (lamAdd * (a[0] - x) - a[1]) mod primeCurve
   result = (x, y)
 
 proc ecDouble(a: tuple): (BigInt, BigInt) =
   var
-    lam = ((3.initBigInt * a[0] * a[0] + Acurve) * modinv(2.initBigInt * a[1]))
-    x = ((lam * lam) - (2.initBigInt * a[0])) mod Pcurve
-    y = (lam * (a[0] - x) - a[1]) mod Pcurve
-  lam = lam mod Pcurve
+    lam = ((3.initBigInt * a[0] * a[0] + Acurve) * invmod(2.initBigInt * a[1], primeCurve))
+    x = ((lam * lam) - (2.initBigInt * a[0])) mod primeCurve
+    y = (lam * (a[0] - x) - a[1]) mod primeCurve
+  lam = lam mod primeCurve
   result = (x, y)
 
 proc ecMultiply(genPoint: tuple, scalarHex: BigInt): (BigInt, BigInt) =
-  if scalarHex == 0 or scalarHex >= N:
+  if scalarHex == zero or scalarHex >= numberPoints:
     raise newException(Exception, "Invalid Scalar/Private Key")
   var
     scalarBin = scalarHex.toString(base = 2)
@@ -80,7 +63,7 @@ proc main() =
   echo "04", publicKey[0].toString(base = 16).align(64, '0'), publicKey[1].toString(base = 16).align(64, '0')
   echo ""
   echo "the official Public Key - compressed:"
-  echo if publicKey[1] mod 2 == 1: "03" & publicKey[0].toString(base = 16).align(64, '0')
+  echo if publicKey[1] mod two == one: "03" & publicKey[0].toString(base = 16).align(64, '0')
        else: "02" & publicKey[0].toString(base = 16).align(64, '0')
 
 main()

examples/nim.cfg

@@ -0,0 +1 @@
+path = "$projectPath/../src"

examples/pidigits.nim

@@ -1,10 +1,22 @@
-# Translation of http://benchmarksgame.alioth.debian.org/u32/program.php?test=pidigits&lang=go&id=4
+# This program prints as much pi digits as the user indicates
+# with the first command line argument
+# This program is an extension of the solution for https://rosettacode.org/wiki/Pi
+# translated from former website http://benchmarksgame.alioth.debian.org
 
-import os, strutils, unsigned, bigints
+import std/[os, strutils, options]
+import bigints
+
+const
+  zero = 0.initBigInt
+  one = 1.initBigInt
+  two = 2.initBigInt
+  ten = 10.initBigInt
+let
+  mask = (one shl 32) - one
 
 var
-  tmp1, tmp2, tmp3, acc, k, dd = initBigInt(0)
-  den, num, k2 = initBigInt(1)
+  tmp1, tmp2, tmp3, acc, k = zero
+  den, num, k2 = one
 
 proc extractDigit(): int32 =
   if num > acc:
@@ -20,35 +32,49 @@ proc extractDigit(): int32 =
   if tmp2 >= den:
     return -1
 
-  result = int32(tmp1.limbs[0])
+  result = get(toSignedInt[int32](tmp1 and mask))
 
 proc eliminateDigit(d: int32) =
-  acc -= den * d
-  acc *= 10
-  num *= 10
+  acc -= den * d.initBigInt
+  acc *= ten
+  num *= ten
 
 proc nextTerm() =
-  k += 1
-  k2 += 2
+  k += one
+  k2 += two
   tmp1 = num shl 1
   acc += tmp1
   acc *= k2
   den *= k2
   num *= k
 
-let n = parseInt(paramStr(1))
+proc findPiDigit(): int32 =
+  result = -1
+  while result < 0:
+    nextTerm()
+    result = extractDigit()
+
 var i = 0
+if paramCount() == 0:
+  # prints an infinite amount of pi digits
+  while true:
+    var d: int32 = findPiDigit()
+    stdout.write chr(ord('0') + d)
+    inc i
+    if i == 40:
+      echo ""
+      i = 0
+    eliminateDigit(d)
 
-while i < n:
-  var d: int32 = -1
-  while d < 0:
-    nextTerm()
-    d = extractDigit()
+let n = parseInt(paramStr(1))
 
+if n <= 0:
+  quit("The number you entered is negative. Please specify a strictly positive number")
+
+while i < n:
+  var d: int32 = findPiDigit()
   stdout.write(chr(ord('0') + d))
   inc(i)
-  if i mod 10 == 0:
+  if i mod 40 == 0:
     echo "\t:", i
-  if i >= n:
-    break
   eliminateDigit(d)

examples/rc_combperm.nim

@@ -1,19 +1,19 @@
-# Solution for http://rosettacode.org/wiki/Combinations_and_permutations
+# Solution for https://rosettacode.org/wiki/Combinations_and_permutations
 import bigints
 
 proc perm(n, k: int32): BigInt =
-  result = initBigInt 1
+  result = initBigInt(1)
   var
-    k = n - k
-    n = n
+    k = initBigInt(n - k)
+    n = initBigInt(n)
   while n > k:
     result *= n
     dec n
 
 proc comb(n, k: int32): BigInt =
   result = perm(n, k)
-  var k = k
-  while k > 0:
+  var k = initBigInt(k)
+  while k > 0.initBigInt:
     result = result div k
     dec k
 

examples/rc_godtheinteger.nim

@@ -1,4 +1,4 @@
-# Solution for http://rosettacode.org/wiki/9_billion_names_of_God_the_integer#Python
+# Solution for https://rosettacode.org/wiki/9_billion_names_of_God_the_integer#Python
 import bigints
 
 var cache = @[@[1.initBigInt]]
@@ -14,14 +14,15 @@ proc cumu(n: int): seq[BigInt] =
 proc row(n: int): seq[BigInt] =
   let r = cumu n
   result = @[]
-  for i in 0 .. <n:
+  for i in 0 ..< n:
     result.add r[i+1] - r[i]
 
 echo "rows:"
 for x in 1..10:
   echo row x
 
 echo "sums:"
-for x in [23, 123, 1234, 12345]:
+# for 12345 this implementation is too slow, for a faster implementation see rc_godtheinteger2.nim
+for x in [23, 123, 1234]:
   let c = cumu(x)
   echo x, " ", c[c.high]

examples/rc_godtheinteger2.nim

@@ -1,4 +1,4 @@
-# Solution for http://rosettacode.org/wiki/9_billion_names_of_God_the_integer#Python
+# Solution for https://rosettacode.org/wiki/9_billion_names_of_God_the_integer#Python
 import bigints
 
 var p = @[1.initBigInt]

examples/rc_hammingnumbers.nim

@@ -1,27 +1,31 @@
-# Translation of http://rosettacode.org/wiki/Hamming_numbers#Another_implementation_of_same_approach
+# Translation of https://rosettacode.org/wiki/Hamming_numbers#Another_implementation_of_same_approach
+import bigints
 
-import bigints, math
+const
+  two = initBigInt(2)
+  three = initBigInt(3)
+  five = initBigInt(5)
 
 proc hamming(limit: int): BigInt =
   var
     h = newSeq[BigInt](limit)
-    x2 = initBigInt(2)
-    x3 = initBigInt(3)
-    x5 = initBigInt(5)
+    x2 = two
+    x3 = three
+    x5 = five
     i, j, k = 0
   for i in 0..h.high: h[i] = initBigInt(1)
 
-  for n in 1 .. < limit:
+  for n in 1 ..< limit:
     h[n] = min([x2, x3, x5])
     if x2 == h[n]:
       inc i
-      x2 = h[i] * 2
+      x2 = h[i] * two
     if x3 == h[n]:
       inc j
-      x3 = h[j] * 3
+      x3 = h[j] * three
     if x5 == h[n]:
       inc k
-      x5 = h[k] * 5
+      x5 = h[k] * five
 
   result = h[h.high]
 

examples/rc_integersequence.nim

@@ -1,6 +1,8 @@
+# This example includes an infinite loop that has to be interrupted by Ctrl+C
 import bigints
 
+const one = 1.initBigInt
 var i = 0.initBigInt
 while true:
-  i += 1
+  i += one
   echo i

examples/rc_leftfactorials.nim

@@ -1,26 +1,37 @@
-import iterutils, bigints
+import bigints
 
-proc lfact: iterator: BigInt =
-  result = iterator: BigInt =
-    yield 0.initBigInt
-    var
-      fact = 1.initBigInt
-      sum = 0.initBigInt
-      n = 1.initBigInt
-    while true:
-      sum += fact
-      fact *= n
-      n += 1
-      yield sum
+const
+  one = 1.initBigInt
+  zero = 0.initBigInt
 
-echo "first 11:"
-for i in lfact().slice(last = 10):
-  echo "  ", i
+iterator lfact: BigInt =
+  yield zero
+  var
+    fact = one
+    sum = zero
+    n = one
+  while true:
+    sum += fact
+    fact *= n
+    n += one
+    yield sum
 
-echo "20 through 110 (inclusive) by tens:"
-for i in lfact().slice(20, 110, 10):
-  echo "  ", i
+var i = 0
+for n in lfact():
+  if i == 0:
+    echo "first 11:"
+  if i == 20:
+    echo "20 through 110 (inclusive) by tens:"
+  if i == 1000:
+    echo "Digits in 1,000 through 10,000 (inclusive) by thousands:"
+
+  if i <= 10:
+    echo i, ": ", n
+  elif i <= 110 and i mod 10 == 0:
+    echo i, ": ", n
+  elif i >= 1000 and i <= 10_000 and i mod 1000 == 0:
+    echo i, ": ", ($n).len
+  elif i > 10_000:
+    break
+  inc i
 
-echo "Digits in 1,000 through 10,000 (inclusive) by thousands:"
-for i in lfact().slice(1_000, 10_000, 1_000):
-  echo "  ", ($i).len

examples/rc_paraffins.nim

@@ -1,22 +1,26 @@
-# Solution for http://rosettacode.org/wiki/Paraffins
+# Solution for https://rosettacode.org/wiki/Paraffins
 import bigints
 
 const
   nMax: int32 = 250
   nBranches: int32 = 4
 
+const
+  one = 1.initBigInt
+  zero = 0.initBigInt
+
 var rooted, unrooted: array[nMax + 1, BigInt]
-rooted[0..1] = [1.initBigInt, 1.initBigInt]
-unrooted[0..1] = [1.initBigInt, 1.initBigInt]
+rooted[0..1] = [one, one]
+unrooted[0..1] = [one, one]
 for i in 2 .. nMax:
-  rooted[i] = 0.initBigInt
-  unrooted[i] = 0.initBigInt
+  rooted[i] = zero
+  unrooted[i] = zero
 
 proc choose(m: BigInt, k: int32): BigInt =
   result = m
   if k == 1: return
-  for i in 1 .. < k:
-    result = result * (m + i) div (i + 1)
+  for i in 1 ..< k:
+    result = result * (m + i.initBigInt) div (i + 1).initBigInt
 
 proc tree(br, n, l, sum: int32, cnt: BigInt) =
   var s: int32 = 0
@@ -33,8 +37,9 @@ proc tree(br, n, l, sum: int32, cnt: BigInt) =
       tree b, m, l, s, c
 
 proc bicenter(s: int32) =
+  var s = s
   if (s and 1) == 0:
-    unrooted[s] += rooted[s div 2] * (rooted[s div 2] + 1) div 2
+    unrooted[s] += rooted[s div 2] * (rooted[s div 2] + 1.initBigInt) div 2.initBigInt
 
 for n in 1 .. nMax:
   tree 0, n, n, 1, 1.initBigInt