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Use corefx implementation

This commit is contained in:
Ben Adams 2015-10-07 16:51:10 -04:00
parent 8bf2c814d6
commit 05418dd18a
1 changed files with 11 additions and 5 deletions
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16
src/Microsoft.AspNet.Server.Kestrel/Infrastructure/LongExtensions.cs
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@ -7,12 +7,18 @@ namespace Microsoft.AspNet.Server.Kestrel.Extensions
{
public static int BitCount(this long value)
{
// Parallel bit count for a 64-bit integer
// see https://github.com/dotnet/corefx/blob/master/src/System.Reflection.Metadata/src/System/Reflection/Internal/Utilities/BitArithmetic.cs
const ulong Mask01010101 = 0x5555555555555555UL;
const ulong Mask00110011 = 0x3333333333333333UL;
const ulong Mask00001111 = 0x0F0F0F0F0F0F0F0FUL;
const ulong Mask00000001 = 0x0101010101010101UL;
var v = (ulong)value;
v = v - ((v >> 1) & 0x5555555555555555);
v = (v & 0x3333333333333333) + ((v >> 2) & 0x3333333333333333);
v = (v + (v >> 4) & 0x0f0f0f0f0f0f0f0f);
return (int)((v * 0x0101010101010101) >> 56);
v = v - ((v >> 1) & Mask01010101);
v = (v & Mask00110011) + ((v >> 2) & Mask00110011);
return (int)(unchecked(((v + (v >> 4)) & Mask00001111) * Mask00000001) >> 56);
}
}
}