Implement exponentiation, test mul, split mul/div tests

stint/private/uint_exp.nim

@@ -1,50 +0,0 @@
-# Stint
-# Copyright 2018 Status Research & Development GmbH
-# Licensed under either of
-#
-#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
-#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
-#
-# at your option. This file may not be copied, modified, or distributed except according to those terms.
-
-import
-  ./datatypes,
-  ./uint_bitwise_ops, ./uint_mul, ./initialization, ./uint_comparison
-
-func pow*(x: UintImpl, y: Natural): UintImpl =
-  ## Compute ``x`` to the power of ``y``,
-  ## ``x`` must be non-negative
-
-  # Implementation uses exponentiation by squaring
-  # See Nim math module: https://github.com/nim-lang/Nim/blob/4ed24aa3eb78ba4ff55aac3008ec3c2427776e50/lib/pure/math.nim#L429
-  # And Eli Bendersky's blog: https://eli.thegreenplace.net/2009/03/21/efficient-integer-exponentiation-algorithms
-
-  var (x, y) = (x, y)
-  result = one(type x)
-
-  while true:
-    if bool(y and 1): # if y is odd
-      result = result * x
-    y = y shr 1
-    if y == 0:
-      break
-    x = x * x
-
-func pow*(x: UintImpl, y: UintImpl): UintImpl =
-  ## Compute ``x`` to the power of ``y``,
-  ## ``x`` must be non-negative
-
-  # Implementation uses exponentiation by squaring
-  # See Nim math module: https://github.com/nim-lang/Nim/blob/4ed24aa3eb78ba4ff55aac3008ec3c2427776e50/lib/pure/math.nim#L429
-  # And Eli Bendersky's blog: https://eli.thegreenplace.net/2009/03/21/efficient-integer-exponentiation-algorithms
-
-  var (x, y) = (x, y)
-  result = one(type x)
-
-  while true:
-    if y.isOdd:
-      result = result * x
-    y = y shr 1
-    if y.isZero:
-      break
-    x = x * x

stint/uintops.nim

@@ -23,18 +23,22 @@ export StUint
 
 func setZero*(a: var StUint) =
   ## Set ``a`` to 0
-  zeroMem(a[0].addr, sizeof(a))
+  for i in 0 ..< a.limbs.len:
+    a[i] = 0
+
+func setSmallInt(a: var StUint, k: Word) =
+  ## Set ``a`` to k
+  when cpuEndian == littleEndian:
+    a.limbs[0] = k
+    for i in 1 ..< a.limbs.len:
+      a.limbs[i] = 0
+  else:
+    a.limbs[^1] = k
+    for i in 0 ..< a.limb.len - 1:
+      a.limbs[i] = 0
 
 func setOne*(a: var StUint) =
-  ## Set ``a`` to 1
+  setSmallInt(a, 1)
-  when cpuEndian == littleEndian:
-    a.limbs[0] = 1
-    when a.limbs.len > 1:
-      zeroMem(a.limbs[1].addr, (a.limbs.len - 1) * sizeof(SecretWord))
-  else:
-    a.limbs[^1] = 1
-    when a.limbs.len > 1:
-      zeroMem(a.limbs[0].addr, (a.len - 1) * sizeof(SecretWord))
 
 func zero*[bits: static[int]](T: typedesc[Stuint[bits]]): T {.inline.} =
   ## Returns the zero of the input type
@@ -42,7 +46,7 @@ func zero*[bits: static[int]](T: typedesc[Stuint[bits]]): T {.inline.} =
 
 func one*[bits: static[int]](T: typedesc[Stuint[bits]]): T {.inline.} =
   ## Returns the one of the input type
-  result.limbs.setOne()
+  result.setOne()
 
 func high*[bits](_: typedesc[Stuint[bits]]): Stuint[bits] {.inline.} =
   for wr in leastToMostSig(result):
@@ -279,8 +283,52 @@ func `*`*(a, b: Stuint): Stuint =
   result.clearExtraBits()
 
 {.pop.}
-# Division & Modulo
-# --------------------------------------------------------
 
 # Exponentiation
 # --------------------------------------------------------
+
+{.push raises: [], noInit, gcsafe.}
+
+func pow*(a: Stuint, e: Natural): Stuint =
+  ## Compute ``a`` to the power of ``e``,
+  ## ``e`` must be non-negative
+
+  # Implementation uses exponentiation by squaring
+  # See Nim math module: https://github.com/nim-lang/Nim/blob/4ed24aa3eb78ba4ff55aac3008ec3c2427776e50/lib/pure/math.nim#L429
+  # And Eli Bendersky's blog: https://eli.thegreenplace.net/2009/03/21/efficient-integer-exponentiation-algorithms
+
+  var (a, e) = (a, e)
+  result.setOne()
+
+  while true:
+    if bool(e and 1): # if y is odd
+      result = result * a
+    e = e shr 1
+    if e == 0:
+      break
+    a = a * a
+
+func pow*[aBits, eBits](a: Stuint[aBits], e: Stuint[eBits]): Stuint[aBits] =
+  ## Compute ``x`` to the power of ``y``,
+  ## ``x`` must be non-negative
+
+  # Implementation uses exponentiation by squaring
+  # See Nim math module: https://github.com/nim-lang/Nim/blob/4ed24aa3eb78ba4ff55aac3008ec3c2427776e50/lib/pure/math.nim#L429
+  # And Eli Bendersky's blog: https://eli.thegreenplace.net/2009/03/21/efficient-integer-exponentiation-algorithms
+
+  var (a, e) = (a, e)
+  result.setOne()
+
+  while true:
+    if e.isOdd:
+      result = result * a
+    e = e shr 1
+    if e.isZero:
+      break
+    a = a * a
+
+{.pop.}
+
+
+# Division & Modulo
+# --------------------------------------------------------

tests/test_uint_divmod.nim

@@ -9,9 +9,6 @@
 
 import ../stint, unittest, test_helpers
 
-template chkMul(chk: untyped, a, b, c: string, bits: int) =
-  chk (fromHex(StUint[bits], a) * fromHex(StUint[bits], b)) == fromHex(StUint[bits], c)
-
 template chkDiv(chk: untyped, a, b, c: string, bits: int) =
   chk (fromHex(StUint[bits], a) div fromHex(StUint[bits], b)) == fromHex(StUint[bits], c)
 
@@ -21,41 +18,7 @@ template chkMod(chk: untyped, a, b, c: string, bits: int) =
 template chkDivMod(chk: untyped, a, b, c, d: string, bits: int) =
   chk divmod(fromHex(StUint[bits], a), fromHex(StUint[bits], b)) == (fromHex(StUint[bits], c), fromHex(StUint[bits], d))
 
-template testMuldiv(chk, tst: untyped) =
+template testdivmod(chk, tst: untyped) =
-  tst "operator `mul`":
-    chkMul(chk, "0", "3", "0", 8)
-    chkMul(chk, "1", "3", "3", 8)
-    chkMul(chk, "64", "3", "2C", 8) # overflow
-
-    chkMul(chk, "0", "3", "0", 16)
-    chkMul(chk, "1", "3", "3", 16)
-    chkMul(chk, "64", "3", "12C", 16)
-    chkMul(chk, "1770", "46", "68A0", 16) # overflow
-
-    chkMul(chk, "0", "3", "0", 32)
-    chkMul(chk, "1", "3", "3", 32)
-    chkMul(chk, "64", "3", "12C", 32)
-    chkMul(chk, "1770", "46", "668A0", 32)
-    chkMul(chk, "13880", "13880", "7D784000", 32) # overflow
-
-    chkMul(chk, "0", "3", "0", 64)
-    chkMul(chk, "1", "3", "3", 64)
-    chkMul(chk, "64", "3", "12C", 64)
-    chkMul(chk, "1770", "46", "668A0", 64)
-    chkMul(chk, "13880", "13880", "17D784000", 64)
-    chkMul(chk, "3B9ACA00", "E8D4A51000", "35C9ADC5DEA00000", 64) # overflow
-
-    chkMul(chk, "0", "3", "0", 128)
-    chkMul(chk, "1", "3", "3", 128)
-    chkMul(chk, "64", "3", "12C", 128)
-    chkMul(chk, "1770", "46", "668A0", 128)
-    chkMul(chk, "13880", "13880", "17D784000", 128)
-    chkMul(chk, "3B9ACA00", "E8D4A51000", "3635C9ADC5DEA00000", 128)
-    chkMul(chk, "25295F0D1", "10", "25295F0D10", 128)
-    chkMul(chk, "123456789ABCDEF00", "123456789ABCDEF00", "4b66dc33f6acdca5e20890f2a5210000", 128) # overflow
-
-    chkMul(chk, "123456789ABCDEF00", "123456789ABCDEF00", "14b66dc33f6acdca5e20890f2a5210000", 256)
-
   tst "operator `div`":
     chkDiv(chk, "0", "3", "0", 8)
     chkDiv(chk, "1", "3", "0", 8)
@@ -212,44 +175,10 @@ template testMuldiv(chk, tst: untyped) =
     chkDivMod(chk, "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", "27", "6906906906906906906906906906906", "15", 128)
 
 static:
-  testMuldiv(ctCheck, ctTest)
+  testdivmod(ctCheck, ctTest)
 
 suite "Wider unsigned int muldiv coverage":
-  testMuldiv(check, test)
+  testdivmod(check, test)
-
-suite "Testing unsigned int multiplication implementation":
-  test "Multiplication with result fitting in low half":
-
-    let a = 10000.stuint(64)
-    let b = 10000.stuint(64)
-
-    check: cast[uint64](a*b) == 100_000_000'u64 # need 27-bits
-
-  test "Multiplication with result overflowing low half":
-
-    let a = 1_000_000.stuint(64)
-    let b = 1_000_000.stuint(64)
-
-    check: cast[uint64](a*b) == 1_000_000_000_000'u64 # need 40 bits
-
-  test "Full overflow is handled like native unsigned types":
-
-    let a = 1_000_000_000.stuint(64)
-    let b = 1_000_000_000.stuint(64)
-    let c = 1_000.stuint(64)
-
-    let x = 1_000_000_000'u64
-    let y = 1_000_000_000'u64
-    let z = 1_000'u64
-    let w = x*y*z
-
-    #check: cast[uint64](a*b*c) == 1_000_000_000_000_000_000_000'u64 # need 70-bits
-    check: cast[uint64](a*b*c) == w
-
-  test "Nim v1.0.2 32 bit type inference rule changed":
-    let x = 9975492817.stuint(256)
-    let y = 16.stuint(256)
-    check x * y == 159607885072.stuint(256)
 
 suite "Testing unsigned int division and modulo implementation":
   test "Divmod(100, 13) returns the correct result":

tests/test_uint_endians2.nim

@@ -9,6 +9,7 @@
 
 import ../stint, unittest, stew/byteutils, test_helpers
 
+
 template chkSwapBytes(chk: untyped, bits: int, hex: string) =
   # dumpHex already do the job to swap the output if
   # we use `littleEndian` on both platform

tests/test_uint_mul.nim

@@ -0,0 +1,88 @@
+# Stint
+# Copyright 2018 Status Research & Development GmbH
+# Licensed under either of
+#
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+#
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+import ../stint, unittest, test_helpers
+
+template chkMul(chk: untyped, a, b, c: string, bits: int) =
+  chk (fromHex(Stuint[bits], a) * fromHex(Stuint[bits], b)) == fromHex(Stuint[bits], c)
+
+template testMul(chk, tst: untyped) =
+  tst "operator `mul`":
+    chkMul(chk, "0", "3", "0", 8)
+    chkMul(chk, "1", "3", "3", 8)
+    chkMul(chk, "64", "3", "2C", 8) # overflow
+
+    chkMul(chk, "0", "3", "0", 16)
+    chkMul(chk, "1", "3", "3", 16)
+    chkMul(chk, "64", "3", "12C", 16)
+    chkMul(chk, "1770", "46", "68A0", 16) # overflow
+
+    chkMul(chk, "0", "3", "0", 32)
+    chkMul(chk, "1", "3", "3", 32)
+    chkMul(chk, "64", "3", "12C", 32)
+    chkMul(chk, "1770", "46", "668A0", 32)
+    chkMul(chk, "13880", "13880", "7D784000", 32) # overflow
+
+    chkMul(chk, "0", "3", "0", 64)
+    chkMul(chk, "1", "3", "3", 64)
+    chkMul(chk, "64", "3", "12C", 64)
+    chkMul(chk, "1770", "46", "668A0", 64)
+    chkMul(chk, "13880", "13880", "17D784000", 64)
+    chkMul(chk, "3B9ACA00", "E8D4A51000", "35C9ADC5DEA00000", 64) # overflow
+
+    chkMul(chk, "0", "3", "0", 128)
+    chkMul(chk, "1", "3", "3", 128)
+    chkMul(chk, "64", "3", "12C", 128)
+    chkMul(chk, "1770", "46", "668A0", 128)
+    chkMul(chk, "13880", "13880", "17D784000", 128)
+    chkMul(chk, "3B9ACA00", "E8D4A51000", "3635C9ADC5DEA00000", 128)
+    chkMul(chk, "25295F0D1", "10", "25295F0D10", 128)
+    chkMul(chk, "123456789ABCDEF00", "123456789ABCDEF00", "4b66dc33f6acdca5e20890f2a5210000", 128) # overflow
+
+    chkMul(chk, "123456789ABCDEF00", "123456789ABCDEF00", "14b66dc33f6acdca5e20890f2a5210000", 256)
+
+static:
+  testMul(ctCheck, ctTest)
+
+suite "Wider unsigned int muldiv coverage":
+  testMul(check, test)
+
+suite "Testing unsigned int multiplication implementation":
+  test "Multiplication with result fitting in low half":
+
+    let a = 10000.stuint(64)
+    let b = 10000.stuint(64)
+
+    check: cast[uint64](a*b) == 100_000_000'u64 # need 27-bits
+
+  test "Multiplication with result overflowing low half":
+
+    let a = 1_000_000.stuint(64)
+    let b = 1_000_000.stuint(64)
+
+    check: cast[uint64](a*b) == 1_000_000_000_000'u64 # need 40 bits
+
+  test "Full overflow is handled like native unsigned types":
+
+    let a = 1_000_000_000.stuint(64)
+    let b = 1_000_000_000.stuint(64)
+    let c = 1_000.stuint(64)
+
+    let x = 1_000_000_000'u64
+    let y = 1_000_000_000'u64
+    let z = 1_000'u64
+    let w = x*y*z
+
+    #check: cast[uint64](a*b*c) == 1_000_000_000_000_000_000_000'u64 # need 70-bits
+    check: cast[uint64](a*b*c) == w
+
+  test "Nim v1.0.2 32 bit type inference rule changed":
+    let x = 9975492817.stuint(256)
+    let y = 16.stuint(256)
+    check x * y == 159607885072.stuint(256)