1 files changed, 83 insertions, 0 deletions
diff --git a/src/inc/opinfo.h b/src/inc/opinfo.h
new file mode 100644
index 0000000000..d98c006ecd
--- /dev/null
+++ b/src/inc/opinfo.h
@@ -0,0 +1,83 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+
+/***************************************************************************/
+/*                                OpInfo.h                                 */
+/***************************************************************************/
+
+/* contains OpInfo, a wrapper that allows you to get useful information
+   about IL opcodes, and how to decode them */
+
+/***************************************************************************/
+
+#ifndef OpInfo_h
+#define OpInfo_h
+
+#include "openum.h"
+
+	// Decribes the flow of control properties of the instruction
+enum OpFlow {
+	FLOW_META,			// not a real instuction
+	FLOW_CALL,			// a call instruction
+	FLOW_BRANCH,			// unconditional branch, does not fall through
+	FLOW_COND_BRANCH,	// may fall through
+	FLOW_PHI,			
+	FLOW_THROW,
+	FLOW_BREAK,
+	FLOW_RETURN,		
+	FLOW_NEXT,			// flows into next instruction (none of the above)
+};
+
+	// These are all the possible arguments for the instruction
+/****************************************************************************/
+union OpArgsVal {
+	__int32  i;
+	__int64 i8;
+	double   r;
+	struct {
+		unsigned count;
+		int* targets;   // targets are pcrelative displacements (little-endian)
+		} switch_;
+	struct {
+		unsigned count;
+		unsigned short* vars;
+		} phi;
+};
+
+/***************************************************************************/
+
+	// OpInfo parses a il instrution into an opcode, and a arg and updates the IP
+class OpInfo {
+public:
+	OpInfo()			  { data = 0; }
+	OpInfo(OPCODE opCode) { _ASSERTE(opCode < CEE_COUNT); data = &table[opCode]; } 
+
+		// fetch instruction at 'instrPtr, fills in 'args' returns pointer 
+		// to next instruction 
+	const unsigned char* fetch(const unsigned char* instrPtr, OpArgsVal* args);	
+
+	const char* getName() 	 	{ return(data->name); }
+	OPCODE_FORMAT getArgsInfo()	{ return(OPCODE_FORMAT(data->format & PrimaryMask)); }
+	OpFlow 		getFlow()	 	{ return(data->flow); }
+	OPCODE 		getOpcode()	 	{ return((OPCODE) (data-table)); }
+    int         getNumPop()     { return(data->numPop); }
+    int         getNumPush()    { return(data->numPush); }
+
+private:
+	struct OpInfoData {
+        const char* name;
+        OPCODE_FORMAT format  	: 8;
+		OpFlow     	flow		: 8;
+		int     	numPop		: 3;	// < 0 means depends on instr args
+		int       	numPush		: 3;	// < 0 means depends on instr args
+        OPCODE      opcode      : 10;  	// This is the same as the index into the table
+    };
+
+	static OpInfoData table[];
+private:
+	OpInfoData* data;
+};
+
+#endif