From 1dd8341715a4444021efa9776da7a907cd622242 Mon Sep 17 00:00:00 2001
From: Terence Parr <parrt@antlr.org>
Date: Tue, 13 May 2014 16:31:38 -0700
Subject: [PATCH] borked up merge. fixed now.

---
 src/vm/Bytecode.java |  8 --------
 src/vm/Test.java     | 14 +++++---------
 src/vm/VM.java       | 22 ++++++++++++++++++++++
 3 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/src/vm/Bytecode.java b/src/vm/Bytecode.java
index ff78a40..e3acfbc 100644
--- a/src/vm/Bytecode.java
+++ b/src/vm/Bytecode.java
@@ -19,13 +19,8 @@ public Instruction(String name, int nargs) {
 	public static final short IEQ  = 5;     // int equal
 	public static final short BR   = 6;     // branch
 	public static final short BRT  = 7;     // branch if true
-<<<<<<< HEAD
 	public static final short BRF  = 8;     // branch if true
 	public static final short ICONST = 9;   // push constant integer
-=======
-	public static final short BRF  = 8;    // branch if true
-	public static final short ICONST = 9;  // push constant integer
->>>>>>> master
 	public static final short LOAD   = 10;  // load from local context
 	public static final short GLOAD  = 11;  // load from global memory
 	public static final short STORE  = 12;  // store in local context
@@ -33,11 +28,8 @@ public Instruction(String name, int nargs) {
 	public static final short PRINT  = 14;  // print stack top
 	public static final short POP  = 15;    // throw away top of stack
 	public static final short HALT = 16;
-<<<<<<< HEAD
 	public static final short CALL = 17;
 	public static final short RET  = 18;    // return with/without value
-=======
->>>>>>> master
 
 	public static Instruction[] instructions = new Instruction[] {
 		null, // <INVALID>
diff --git a/src/vm/Test.java b/src/vm/Test.java
index c473574..fed3886 100644
--- a/src/vm/Test.java
+++ b/src/vm/Test.java
@@ -2,13 +2,18 @@
 
 import static vm.Bytecode.BR;
 import static vm.Bytecode.BRF;
+import static vm.Bytecode.CALL;
 import static vm.Bytecode.GLOAD;
 import static vm.Bytecode.GSTORE;
 import static vm.Bytecode.HALT;
 import static vm.Bytecode.IADD;
 import static vm.Bytecode.ICONST;
 import static vm.Bytecode.ILT;
+import static vm.Bytecode.IMUL;
+import static vm.Bytecode.ISUB;
+import static vm.Bytecode.LOAD;
 import static vm.Bytecode.PRINT;
+import static vm.Bytecode.RET;
 
 public class Test {
 	static int[] hello = {
@@ -44,7 +49,6 @@ public class Test {
 			HALT					// 24
 	};
 
-<<<<<<< HEAD
 	static int[] factorial = {
 //.def fact: ARGS=1, LOCALS=0		ADDRESS
 //	IF N < 2 RETURN 1
@@ -73,14 +77,6 @@ public class Test {
 
 	public static void main(String[] args) {
 		VM vm = new VM(factorial, 22, 0);
-=======
-	public static void main(String[] args) {
-		VM vm = new VM(hello, 0, 0);
-		vm.trace = true;
-		vm.exec();
-
-		vm = new VM(loop, 0, 2);
->>>>>>> master
 		vm.trace = true;
 		vm.exec();
 	}
diff --git a/src/vm/VM.java b/src/vm/VM.java
index 4330603..ca9207a 100644
--- a/src/vm/VM.java
+++ b/src/vm/VM.java
@@ -6,6 +6,7 @@
 import static vm.Bytecode.BR;
 import static vm.Bytecode.BRF;
 import static vm.Bytecode.BRT;
+import static vm.Bytecode.CALL;
 import static vm.Bytecode.GLOAD;
 import static vm.Bytecode.GSTORE;
 import static vm.Bytecode.HALT;
@@ -18,6 +19,7 @@
 import static vm.Bytecode.LOAD;
 import static vm.Bytecode.POP;
 import static vm.Bytecode.PRINT;
+import static vm.Bytecode.RET;
 import static vm.Bytecode.STORE;
 
 /** A simple stack-based interpreter */
@@ -121,6 +123,26 @@ protected void cpu() {
 				case POP:
 					--sp;
 					break;
+				case CALL :
+					// expects all args on stack
+					addr = code[ip++];			// target addr of function
+					int nargs = code[ip++];		// how many args got pushed
+					stack[++sp] = nargs;	 	// save num args
+					stack[++sp] = fp;		 	// save fp
+					stack[++sp] = ip;		 	// push return address
+					fp = sp;					// fp points at ret addr on stack
+					ip = addr;					// jump to function
+					// code preamble of func must push space for locals
+					break;
+				case RET:
+					int rvalue = stack[sp--];	// pop return value
+					sp = fp;					// jump over locals to fp which points at ret addr
+					ip = stack[sp--];			// pop return address, jump to it
+					fp = stack[sp--];			// restore fp
+					nargs = stack[sp--];		// how many args to throw away?
+					sp -= nargs;				// pop args
+					stack[++sp] = rvalue;	  	// leave result on stack
+					break;
 				default :
 					throw new Error("invalid opcode: "+opcode+" at ip="+(ip-1));
 			}