From 15eb68f1d0c251ea80a97fed3bbdc2237fa15268 Mon Sep 17 00:00:00 2001
From: LDj3SNuD <35856442+LDj3SNuD@users.noreply.github.com>
Date: Sat, 13 Oct 2018 01:10:05 +0200
Subject: [PATCH] Update ASoftFallback.cs

---
 ChocolArm64/Instruction/ASoftFallback.cs | 59 ++++++++++++++++--------
 1 file changed, 40 insertions(+), 19 deletions(-)

diff --git a/ChocolArm64/Instruction/ASoftFallback.cs b/ChocolArm64/Instruction/ASoftFallback.cs
index a7bc108591..c356048923 100644
--- a/ChocolArm64/Instruction/ASoftFallback.cs
+++ b/ChocolArm64/Instruction/ASoftFallback.cs
@@ -386,7 +386,7 @@ namespace ChocolArm64.Instruction
 #endregion
 
 #region "Count"
-        public static ulong CountLeadingSigns(ulong Value, int Size)
+        public static ulong CountLeadingSigns(ulong Value, int Size) // Size is 8, 16, 32 or 64 (SIMD&FP or Base Inst.).
         {
             Value ^= Value >> 1;
 
@@ -405,33 +405,54 @@ namespace ChocolArm64.Instruction
 
         private static readonly byte[] ClzNibbleTbl = { 4, 3, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0 };
 
-        public static ulong CountLeadingZeros(ulong Value, int Size)
+        public static ulong CountLeadingZeros(ulong Value, int Size) // Size is 8, 16, 32 or 64 (SIMD&FP or Base Inst.).
         {
-            if (Value == 0)
+            if (Lzcnt.IsSupported && Size >= 32)
             {
-                return (ulong)Size;
+                return Size == 32
+                    ? (ulong)Lzcnt.LeadingZeroCount((uint)Value)
+                    : Lzcnt.LeadingZeroCount(Value);
             }
-
-            int NibbleIdx = Size;
-            int PreCount, Count = 0;
-
-            do
+            else
             {
-                NibbleIdx -= 4;
-                PreCount = ClzNibbleTbl[(Value >> NibbleIdx) & 0b1111];
-                Count += PreCount;
-            }
-            while (PreCount == 4);
+                if (Value == 0ul)
+                {
+                    return (ulong)Size;
+                }
 
-            return (ulong)Count;
+                int NibbleIdx = Size;
+                int PreCount, Count = 0;
+
+                do
+                {
+                    NibbleIdx -= 4;
+                    PreCount = ClzNibbleTbl[(Value >> NibbleIdx) & 0b1111];
+                    Count += PreCount;
+                }
+                while (PreCount == 4);
+
+                return (ulong)Count;
+            }
         }
 
-        public static uint CountSetBits8(uint Value)
+        public static ulong CountSetBits8(ulong Value) // "Size" is 8 (SIMD&FP Inst.).
         {
-            Value = ((Value >> 1) & 0x55) + (Value & 0x55);
-            Value = ((Value >> 2) & 0x33) + (Value & 0x33);
+            if (Popcnt.IsSupported)
+            {
+                return (ulong)Popcnt.PopCount(Value);
+            }
+            else
+            {
+                if (Value == 0xfful)
+                {
+                    return 8ul;
+                }
 
-            return (Value >> 4) + (Value & 0x0f);
+                Value = ((Value >> 1) & 0x55ul) + (Value & 0x55ul);
+                Value = ((Value >> 2) & 0x33ul) + (Value & 0x33ul);
+
+                return (Value >> 4) + (Value & 0x0ful);
+            }
         }
 #endregion