diff --git a/crypto/src/math/BigInteger.cs b/crypto/src/math/BigInteger.cs
index 5b2ea0d87..d84680de5 100644
--- a/crypto/src/math/BigInteger.cs
+++ b/crypto/src/math/BigInteger.cs
@@ -942,7 +942,7 @@ namespace Org.BouncyCastle.Math
int sum = 0;
for (int i = 0; i < magnitude.Length; ++i)
{
- sum += BitCnt(magnitude[i]);
+ sum += Integers.PopCount(magnitude[i]);
}
nBits = sum;
}
@@ -952,21 +952,6 @@ namespace Org.BouncyCastle.Math
}
}
- internal static int BitCnt(uint u)
- {
-#if NETCOREAPP3_0_OR_GREATER
- return BitOperations.PopCount(u);
-#else
- u = u - ((u >> 1) & 0x55555555);
- u = (u & 0x33333333) + ((u >> 2) & 0x33333333);
- u = (u + (u >> 4)) & 0x0f0f0f0f;
- u += (u >> 8);
- u += (u >> 16);
- u &= 0x3f;
- return (int)u;
-#endif
- }
-
private static int CalcBitLength(int sign, int indx, uint[] mag)
{
for (;;)
diff --git a/crypto/src/pqc/crypto/picnic/PicnicUtilities.cs b/crypto/src/pqc/crypto/picnic/PicnicUtilities.cs
index a2f1ca080..d77d7ce29 100644
--- a/crypto/src/pqc/crypto/picnic/PicnicUtilities.cs
+++ b/crypto/src/pqc/crypto/picnic/PicnicUtilities.cs
@@ -34,48 +34,19 @@ namespace Org.BouncyCastle.Pqc.Crypto.Picnic
x ^= data[i];
}
- return (int)Parity16(x);
+ return Integers.PopCount(x) & 1;
}
internal static uint Parity16(uint x)
{
-#if NETCOREAPP3_0_OR_GREATER
- if (Popcnt.IsSupported)
- {
- return Popcnt.PopCount(x & 0xFFFF) & 1U;
- }
-#endif
-
- uint y = x ^ (x >> 1);
-
- y ^= (y >> 2);
- y ^= (y >> 4);
- y ^= (y >> 8);
- return y & 1;
+ return (uint)(Integers.PopCount(x & 0xFFFF) & 1);
}
internal static uint Parity32(uint x)
{
-#if NETCOREAPP3_0_OR_GREATER
- if (Popcnt.IsSupported)
- {
- return Popcnt.PopCount(x) & 1U;
- }
-#endif
-
- /* Compute parity of x using code from Section 5-2 of
- * H.S. Warren, *Hacker's Delight*, Pearson Education, 2003.
- * http://www.hackersdelight.org/hdcodetxt/parity.c.txt
- */
- uint y = (x ^ (x >> 1));
- y ^= (y >> 2);
- y ^= (y >> 4);
- y ^= (y >> 8);
- y ^= (y >> 16);
- return (y & 1);
+ return (uint)(Integers.PopCount(x) & 1);
}
-
/* Set a specific bit in a byte array to a given value */
internal static void SetBitInWordArray(uint[] array, int bitNumber, uint val)
{
diff --git a/crypto/src/util/Integers.cs b/crypto/src/util/Integers.cs
index eff7056b6..87ba9cbb0 100644
--- a/crypto/src/util/Integers.cs
+++ b/crypto/src/util/Integers.cs
@@ -79,6 +79,27 @@ namespace Org.BouncyCastle.Utilities
#endif
}
+ public static int PopCount(int i)
+ {
+ return PopCount((uint)i);
+ }
+
+ [CLSCompliant(false)]
+ public static int PopCount(uint u)
+ {
+#if NETCOREAPP3_0_OR_GREATER
+ return BitOperations.PopCount(u);
+#else
+ u -= (u >> 1) & 0x55555555;
+ u = (u & 0x33333333) + ((u >> 2) & 0x33333333);
+ u = (u + (u >> 4)) & 0x0f0f0f0f;
+ u += (u >> 8);
+ u += (u >> 16);
+ u &= 0x3f;
+ return (int)u;
+#endif
+ }
+
public static int Reverse(int i)
{
return (int)Reverse((uint)i);
diff --git a/crypto/test/src/util/utiltest/IntegersTest.cs b/crypto/test/src/util/utiltest/IntegersTest.cs
index a661144db..91c0bf2b6 100644
--- a/crypto/test/src/util/utiltest/IntegersTest.cs
+++ b/crypto/test/src/util/utiltest/IntegersTest.cs
@@ -32,5 +32,38 @@ namespace Org.BouncyCastle.Utilities.UtilTests
Assert.AreEqual(31, Integers.NumberOfTrailingZeros(int.MinValue));
Assert.AreEqual(32, Integers.NumberOfTrailingZeros(0));
}
+
+ [Test]
+ public void TestPopCount()
+ {
+ Random random = new Random();
+
+ for (int pos = 0; pos <= 24; ++pos)
+ {
+ int seed = Integers.RotateLeft(random.Next(0xFFFFFF) << 8, pos);
+ ImplTestPopCountRange(seed, pos, 0xFF);
+ }
+ }
+
+ private static void ImplTestPopCountRange(int seed, int pos, int count)
+ {
+ for (int i = 0; i < count; ++i)
+ {
+ int n = seed + (i << pos);
+ int expected = SimpleBitCount(n);
+ Assert.AreEqual(expected, Integers.PopCount(n));
+ Assert.AreEqual(expected, Integers.PopCount((uint)n));
+ }
+ }
+
+ private static int SimpleBitCount(int n)
+ {
+ int count = 0;
+ for (int i = 0; i < 32; ++i)
+ {
+ count += (n >> i) & 1;
+ }
+ return count;
+ }
}
}
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