Implement some ARM32 memory instructions and CMP (#565)

* Implement ARM32 memory instructions: LDM, LDR, LDRB, LDRD, LDRH, LDRSB, LDRSH, STM, STR, STRB, STRD, STRH (immediate and register + immediate variants), implement CMP (immediate and register shifted by immediate variants)

* Rename some opcode classes and flag masks for consistency

* Fix a few suboptimal ARM32 codegen issues, only loads should be considered on decoder when checking if Rt == PC, and only NZCV flags should be considered for comparison optimizations

* Take into account Rt2 for LDRD instructions aswell when checking if the instruction changes PC

* Re-align arm32 instructions on the opcode table

1 files changed, 57 insertions, 0 deletions

diff --git a/ChocolArm64/Decoders/OpCode32MemMult.cs b/ChocolArm64/Decoders/OpCode32MemMult.cs
new file mode 100644
index 00000000..652da8a5
--- /dev/null
+++ b/ChocolArm64/Decoders/OpCode32MemMult.cs
@@ -0,0 +1,57 @@
+using ChocolArm64.Instructions;
+
+namespace ChocolArm64.Decoders
+{
+    class OpCode32MemMult : OpCode32, IOpCode32MemMult
+    {
+        public int Rn { get; private set; }
+
+        public int RegisterMask { get; private set; }
+        public int Offset       { get; private set; }
+        public int PostOffset   { get; private set; }
+
+        public bool IsLoad { get; private set; }
+
+        public OpCode32MemMult(Inst inst, long position, int opCode) : base(inst, position, opCode)
+        {
+            Rn = (opCode >> 16) & 0xf;
+
+            bool isLoad = (opCode & (1 << 20)) != 0;
+            bool w      = (opCode & (1 << 21)) != 0;
+            bool u      = (opCode & (1 << 23)) != 0;
+            bool p      = (opCode & (1 << 24)) != 0;
+
+            RegisterMask = opCode & 0xffff;
+
+            int regsSize = 0;
+
+            for (int index = 0; index < 16; index++)
+            {
+                regsSize += (RegisterMask >> index) & 1;
+            }
+
+            regsSize *= 4;
+
+            if (!u)
+            {
+                Offset -= regsSize;
+            }
+
+            if (u == p)
+            {
+                Offset += 4;
+            }
+
+            if (w)
+            {
+                PostOffset = u ? regsSize : -regsSize;
+            }
+            else
+            {
+                PostOffset = 0;
+            }
+
+            IsLoad = isLoad;
+        }
+    }
+}
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