1 files changed, 117 insertions, 0 deletions
diff --git a/T0/Opcode.cs b/T0/Opcode.cs
new file mode 100644
index 000000000000..81d1e9d7d3d8
--- /dev/null
+++ b/T0/Opcode.cs
@@ -0,0 +1,117 @@
+/*
+ * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining 
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+using System;
+using System.Collections.Generic;
+
+abstract class Opcode {
+
+	internal Opcode()
+	{
+	}
+
+	/*
+	 * Execute this opcode.
+	 */
+	internal abstract void Run(CPU cpu);
+
+	/*
+	 * Resolve the target (word reference) for this opcode.
+	 */
+	internal virtual void ResolveTarget(Word target)
+	{
+		throw new Exception("Not a call opcode");
+	}
+
+	/*
+	 * Resolve the jump offset for this opcode. Displacement is
+	 * relative to the address of the opcode that immediately follows
+	 * the jump code; thus, 0 implies no jump at all.
+	 */
+	internal virtual void ResolveJump(int disp)
+	{
+		throw new Exception("Not a jump opcode");
+	}
+
+	/*
+	 * Get the Word that this opcode references; this can happen
+	 * only with "call" and "const" opcodes. For all other opcodes,
+	 * this method returns null.
+	 */
+	internal virtual Word GetReference(T0Comp ctx)
+	{
+		return null;
+	}
+
+	/*
+	 * Get the data block that this opcode references; this can happen
+	 * only with "const" opcodes. For all other opcodes, this method
+	 * returns null.
+	 */
+	internal virtual ConstData GetDataBlock(T0Comp ctx)
+	{
+		return null;
+	}
+
+	/*
+	 * Test whether this opcode may "fall through", i.e. execution
+	 * may at least potentially proceed to the next opcode.
+	 */
+	internal virtual bool MayFallThrough {
+		get {
+			return true;
+		}
+	}
+
+	/*
+	 * Get jump displacement. For non-jump opcodes, this returns 0.
+	 */
+	internal virtual int JumpDisp {
+		get {
+			return 0;
+		}
+	}
+
+	/*
+	 * Get stack effect for this opcode (number of elements added to
+	 * the stack, could be negative). For OpcodeCall, this returns
+	 * 0.
+	 */
+	internal virtual int StackAction {
+		get {
+			return 0;
+		}
+	}
+
+	internal abstract CodeElement ToCodeElement();
+
+	/*
+	 * This method is called for the CodeElement corresponding to
+	 * this opcode, at gcode[off]; it is used to compute actual
+	 * byte jump offsets when converting code to C.
+	 */
+	internal virtual void FixUp(CodeElement[] gcode, int off)
+	{
+	}
+}