From b44355f367a3a7df09b33c290c60ffc16dbd3163 Mon Sep 17 00:00:00 2001
From: Alessandro Gatti <a.gatti@frob.it>
Date: Wed, 8 Jun 2022 20:36:33 +0200
Subject: [PATCH] Use pcodeops for `bitrev` and `byterev`.

---
 .../68000/data/languages/68000.sinc           | 16 ++----
 .../m68kEmulateInstructionStateModifier.java  | 56 +++++++++++++++++++
 2 files changed, 62 insertions(+), 10 deletions(-)

diff --git a/Ghidra/Processors/68000/data/languages/68000.sinc b/Ghidra/Processors/68000/data/languages/68000.sinc
index 5c6ffba27b..f361d129c0 100644
--- a/Ghidra/Processors/68000/data/languages/68000.sinc
+++ b/Ghidra/Processors/68000/data/languages/68000.sinc
@@ -860,20 +860,16 @@ define pcodeop countLeadingZeros;
 
 @ifdef COLDFIRE
 
+define pcodeop bitReverse;
+
 :bitrev regdn is reg315=0x18 & regdn {
-	local dword = regdn;
-	regdn[31,1] = dword[0,1]; regdn[30,1] = dword[1,1]; regdn[29,1] = dword[2,1]; regdn[28,1] = dword[3,1];
-	regdn[27,1] = dword[4,1]; regdn[26,1] = dword[5,1]; regdn[25,1] = dword[6,1]; regdn[24,1] = dword[7,1];
-	regdn[23,1] = dword[8,1]; regdn[22,1] = dword[9,1]; regdn[21,1] = dword[10,1]; regdn[20,1] = dword[11,1];
-	regdn[19,1] = dword[12,1]; regdn[18,1] = dword[13,1]; regdn[17,1] = dword[14,1]; regdn[16,1] = dword[15,1];
-	regdn[15,1] = dword[16,1]; regdn[14,1] = dword[17,1]; regdn[13,1] = dword[18,1]; regdn[12,1] = dword[19,1];
-	regdn[11,1] = dword[20,1]; regdn[10,1] = dword[21,1]; regdn[9,1] = dword[22,1]; regdn[8,1] = dword[23,1];
-	regdn[7,1] = dword[24,1]; regdn[6,1] = dword[25,1]; regdn[5,1] = dword[26,1]; regdn[4,1] = dword[27,1];
-	regdn[3,1] = dword[28,1]; regdn[2,1] = dword[29,1]; regdn[1,1] = dword[30,1]; regdn[0,1] = dword[31,1];
+	regdn = bitReverse(regdn);
 }
 
+define pcodeop byteReverse;
+
 :byterev regdn is reg315=0x58 & regdn {
-	regdn = ((regdn & 0x000000FF) << 24) | ((regdn & 0x0000FF00) << 8) | ((regdn & 0x00FF0000) >> 8) | ((regdn & 0xFF000000) >> 24);
+	regdn = byteReverse(regdn);
 }
 
 @endif # COLDFIRE
diff --git a/Ghidra/Processors/68000/src/main/java/ghidra/program/emulation/m68kEmulateInstructionStateModifier.java b/Ghidra/Processors/68000/src/main/java/ghidra/program/emulation/m68kEmulateInstructionStateModifier.java
index 98a56cd986..04536687ef 100644
--- a/Ghidra/Processors/68000/src/main/java/ghidra/program/emulation/m68kEmulateInstructionStateModifier.java
+++ b/Ghidra/Processors/68000/src/main/java/ghidra/program/emulation/m68kEmulateInstructionStateModifier.java
@@ -50,6 +50,8 @@ public class m68kEmulateInstructionStateModifier extends EmulateInstructionState
 
 		registerPcodeOpBehavior("countLeadingZeros", new CountLeadingZerosOpBehavior());
 		registerPcodeOpBehavior("findFirstOne", new FindFirstOneOpBehavior());
+		registerPcodeOpBehavior("bitReverse", new BitReverseOpBehavior());
+		registerPcodeOpBehavior("byteReverse", new ByteReverseOpBehavior());
 	}
 
 	/**
@@ -142,4 +144,58 @@ public class m68kEmulateInstructionStateModifier extends EmulateInstructionState
 		}
 
 	}
+
+	private static class BitReverseOpBehavior implements OpBehaviorOther {
+
+		@Override
+		public void evaluate(Emulate emu, Varnode out, Varnode[] inputs) {
+			if (out == null) {
+				throw new LowlevelError("CALLOTHER: Bit Reverse op missing required output");
+			}
+
+			if (inputs.length != 2 || inputs[1].getSize() == 0 || !inputs[1].isRegister()) {
+				throw new LowlevelError(
+					"CALLOTHER: Bit Reverse op requires one register varnode input");
+			}
+
+			Varnode in = inputs[1];
+			MemoryState memoryState = emu.getMemoryState();
+
+			long value = memoryState.getValue(in);
+			long size = in.getSize() * 8;
+			long bitFrom = size - 1;
+			long bitTo = 0;
+			long reversed = 0;
+			while (bitFrom >= 0) {
+				reversed |= ((value >> bitFrom) & 1L) << bitTo;
+				bitTo++;
+			}
+
+			memoryState.setValue(out, reversed);
+		}
+
+	}
+
+	private static class ByteReverseOpBehavior implements OpBehaviorOther {
+
+		@Override
+		public void evaluate(Emulate emu, Varnode out, Varnode[] inputs) {
+			if (out == null) {
+				throw new LowlevelError("CALLOTHER: Byte Reverse op missing required output");
+			}
+
+			if (inputs.length != 2 || inputs[1].getSize() == 0 || !inputs[1].isRegister()) {
+				throw new LowlevelError(
+					"CALLOTHER: Byte Reverse op requires one register varnode input");
+			}
+
+			Varnode in = inputs[1];
+			MemoryState memoryState = emu.getMemoryState();
+
+			long value = memoryState.getValue(in);
+			memoryState.setValue(out, ((value & 0x000000FF) << 24) | ((value & 0x0000FF00) << 8) |
+					((value & 0x00FF0000) >> 8) | ((value & 0xFF000000) >> 24));
+		}
+
+	}
 }