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src/Neo.Cryptography.BLS12_381/MathUtility.cs

@@ -26,8 +26,20 @@ public static (ulong low, ulong high) Mac(ulong z, ulong x, ulong y, ulong carry
         return (low, high);
     }
 
+    /// <summary>Produces the full product of two unsigned 64-bit numbers.</summary>
+    /// <param name="a">The first number to multiply.</param>
+    /// <param name="b">The second number to multiply.</param>
+    /// <param name="low">The low 64-bit of the product of the specified numbers.</param>
+    /// <returns>The high 64-bit of the product of the specified numbers.</returns>
     public static ulong BigMul(ulong a, ulong b, out ulong low)
     {
+        // Adaptation of algorithm for multiplication
+        // of 32-bit unsigned integers described
+        // in Hacker's Delight by Henry S. Warren, Jr. (ISBN 0-201-91465-4), Chapter 8
+        // Basically, it's an optimized version of FOIL method applied to
+        // low and high dwords of each operand
+
+        // Use 32-bit uints to optimize the fallback for 32-bit platforms.
         uint al = (uint)a;
         uint ah = (uint)(a >> 32);
         uint bl = (uint)b;