1 files changed, 88 insertions, 0 deletions
diff --git a/src/ARMeilleure/Decoders/OpCodeSimdHelper.cs b/src/ARMeilleure/Decoders/OpCodeSimdHelper.cs
new file mode 100644
index 00000000..02f74d03
--- /dev/null
+++ b/src/ARMeilleure/Decoders/OpCodeSimdHelper.cs
@@ -0,0 +1,88 @@
+namespace ARMeilleure.Decoders
+{
+    public static class OpCodeSimdHelper
+    {
+        public static (long Immediate, int Size) GetSimdImmediateAndSize(int cMode, int op, long imm)
+        {
+            int modeLow = cMode & 1;
+            int modeHigh = cMode >> 1;
+            int size = 0;
+
+            if (modeHigh == 0b111)
+            {
+                switch (op | (modeLow << 1))
+                {
+                    case 0:
+                        // 64-bits Immediate.
+                        // Transform abcd efgh into abcd efgh abcd efgh ...
+                        size = 3;
+                        imm = (long)((ulong)imm * 0x0101010101010101);
+                        break;
+
+                    case 1:
+                        // 64-bits Immediate.
+                        // Transform abcd efgh into aaaa aaaa bbbb bbbb ...
+                        size = 3;
+                        imm = (imm & 0xf0) >> 4 | (imm & 0x0f) << 4;
+                        imm = (imm & 0xcc) >> 2 | (imm & 0x33) << 2;
+                        imm = (imm & 0xaa) >> 1 | (imm & 0x55) << 1;
+
+                        imm = (long)((ulong)imm * 0x8040201008040201);
+                        imm = (long)((ulong)imm & 0x8080808080808080);
+
+                        imm |= imm >> 4;
+                        imm |= imm >> 2;
+                        imm |= imm >> 1;
+                        break;
+
+                    case 2:
+                        // 2 x 32-bits floating point Immediate.
+                        size = 3;
+                        imm = (long)DecoderHelper.Imm8ToFP32Table[(int)imm];
+                        imm |= imm << 32;
+                        break;
+
+                    case 3:
+                        // 64-bits floating point Immediate.
+                        size = 3;
+                        imm = (long)DecoderHelper.Imm8ToFP64Table[(int)imm];
+                        break;
+                }
+            }
+            else if ((modeHigh & 0b110) == 0b100)
+            {
+                // 16-bits shifted Immediate.
+                size = 1; imm <<= (modeHigh & 1) << 3;
+            }
+            else if ((modeHigh & 0b100) == 0b000)
+            {
+                // 32-bits shifted Immediate.
+                size = 2; imm <<= modeHigh << 3;
+            }
+            else if ((modeHigh & 0b111) == 0b110)
+            {
+                // 32-bits shifted Immediate (fill with ones).
+                size = 2; imm = ShlOnes(imm, 8 << modeLow);
+            }
+            else
+            {
+                // 8-bits without shift.
+                size = 0;
+            }
+
+            return (imm, size);
+        }
+
+        private static long ShlOnes(long value, int shift)
+        {
+            if (shift != 0)
+            {
+                return value << shift | (long)(ulong.MaxValue >> (64 - shift));
+            }
+            else
+            {
+                return value;
+            }
+        }
+    }
+}