Split main project into core,graphics and chocolarm4 subproject (#29)

1 files changed, 107 insertions, 0 deletions

diff --git a/ChocolArm64/Decoder/ADecoderHelper.cs b/ChocolArm64/Decoder/ADecoderHelper.cs
new file mode 100644
index 00000000..a2179f49
--- /dev/null
+++ b/ChocolArm64/Decoder/ADecoderHelper.cs
@@ -0,0 +1,107 @@
+using System;
+
+namespace ChocolArm64.Decoder
+{
+    static class ADecoderHelper
+    {
+        public struct BitMask
+        {
+            public long WMask;
+            public long TMask;
+            public int  Pos;
+            public int  Shift;
+            public bool IsUndefined;
+
+            public static BitMask Invalid => new BitMask { IsUndefined = true };
+        }
+
+        public static BitMask DecodeBitMask(int OpCode, bool Immediate)
+        {
+            int ImmS = (OpCode >> 10) & 0x3f;
+            int ImmR = (OpCode >> 16) & 0x3f;
+
+            int N  = (OpCode >> 22) & 1;
+            int SF = (OpCode >> 31) & 1;
+
+            int Length = ABitUtils.HighestBitSet32((~ImmS & 0x3f) | (N << 6));
+
+            if (Length < 1 || (SF == 0 && N != 0))
+            {
+                return BitMask.Invalid;
+            }
+
+            int Size = 1 << Length;
+
+            int Levels = Size - 1;
+
+            int S = ImmS & Levels;
+            int R = ImmR & Levels;
+
+            if (Immediate && S == Levels)
+            {
+                return BitMask.Invalid;
+            }
+
+            long WMask = ABitUtils.FillWithOnes(S + 1);
+            long TMask = ABitUtils.FillWithOnes(((S - R) & Levels) + 1);
+
+            if (R > 0)
+            {
+                WMask  = ABitUtils.RotateRight(WMask, R, Size);
+                WMask &= ABitUtils.FillWithOnes(Size);
+            }
+
+            return new BitMask()
+            {
+                WMask = ABitUtils.Replicate(WMask, Size),
+                TMask = ABitUtils.Replicate(TMask, Size),
+
+                Pos   = ImmS,
+                Shift = ImmR
+            };
+        }
+
+        public static long DecodeImm8Float(long Imm, int Size)
+        {
+            int E = 0, F = 0;
+
+            switch (Size)
+            {
+                case 0: E =  8; F = 23; break;
+                case 1: E = 11; F = 52; break;
+
+                default: throw new ArgumentOutOfRangeException(nameof(Size));
+            }
+
+            long Value = (Imm & 0x3f) << F - 4;
+
+            long EBit = (Imm >> 6) & 1;
+            long SBit = (Imm >> 7) & 1;
+
+            if (EBit != 0)
+            {
+                Value |= (1L << E - 3) - 1 << F + 2;
+            }
+
+            Value |= (EBit ^ 1) << F + E - 1;
+            Value |=  SBit      << F + E;
+
+            return Value;
+        }
+
+        public static long DecodeImm26_2(int OpCode)
+        {
+            return ((long)OpCode << 38) >> 36;
+        }
+
+        public static long DecodeImmS19_2(int OpCode)
+        {
+            return (((long)OpCode << 40) >> 43) & ~3;
+        }
+
+        public static long DecodeImmS14_2(int OpCode)
+        {
+            return (((long)OpCode << 45) >> 48) & ~3;
+        }
+    }
+}
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