From fcbea5f617edb6e3dfa68eb31efa402b4916c032 Mon Sep 17 00:00:00 2001
From: Tom Willemse
Date: Mon, 20 Sep 2021 21:47:41 -0700
Subject: Chapter 21.1 - 21.3

---
 clox/src/vm.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

(limited to 'clox/src/vm.c')

diff --git a/clox/src/vm.c b/clox/src/vm.c
index e35a1e0..709f3d1 100644
--- a/clox/src/vm.c
+++ b/clox/src/vm.c
@@ -29,10 +29,13 @@ static void runtimeError(const char *format, ...) {
 void initVM() {
   resetStack();
   vm.objects = NULL;
+
+  initTable(&vm.globals);
   initTable(&vm.strings);
 }
 
 void freeVM() {
+  freeTable(&vm.globals);
   freeTable(&vm.strings);
   freeObjects();
 }
@@ -70,6 +73,7 @@ static void concatenate() {
 static InterpretResult run() {
 #define READ_BYTE() (*vm.ip++)
 #define READ_CONSTANT() (vm.chunk->constants.values[READ_BYTE()])
+#define READ_STRING() AS_STRING(READ_CONSTANT())
 #define BINARY_OP(valueType, op)                                               \
   do {                                                                         \
     if (!IS_NUMBER(peek(0)) || !IS_NUMBER(peek(1))) {                          \
@@ -108,6 +112,15 @@ static InterpretResult run() {
     case OP_FALSE:
       push(BOOL_VAL(false));
       break;
+    case OP_POP:
+      pop();
+      break;
+    case OP_DEFINE_GLOBAL: {
+      ObjString *name = READ_STRING();
+      tableSet(&vm.globals, name, peek(0));
+      pop();
+      break;
+    }
     case OP_EQUAL: {
       Value b = pop();
       Value a = pop();
@@ -152,7 +165,15 @@ static InterpretResult run() {
       }
       push(NUMBER_VAL(-AS_NUMBER(pop())));
       break;
+    case OP_PRINT: {
+      printValue(pop());
+      printf("\n");
+      break;
+    }
     case OP_RETURN: {
+      /* The book said to remove this, but when I do I get an infinite loop and
+         then a segfault because it keeps trying to add the constant 1 to the
+         stack. */
       printValue(pop());
       printf("\n");
       return INTERPRET_OK;
@@ -162,6 +183,7 @@ static InterpretResult run() {
 
 #undef READ_BYTE
 #undef READ_CONSTANT
+#undef READ_STRING
 #undef BINARY_OP
 }
 
-- 
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