From 9b60cf334cdb030759c54f700d5c122338c5b3a8 Mon Sep 17 00:00:00 2001
From: Tom Willemse
Date: Thu, 29 Jul 2021 23:56:42 -0700
Subject: Chapter 15.3.1

---
 clox/src/chunk.h |  4 ++++
 clox/src/debug.c |  8 ++++++++
 clox/src/main.c  | 12 ++++++++++++
 clox/src/vm.c    | 19 +++++++++++++++++++
 4 files changed, 43 insertions(+)

diff --git a/clox/src/chunk.h b/clox/src/chunk.h
index dcab3df..185f13c 100644
--- a/clox/src/chunk.h
+++ b/clox/src/chunk.h
@@ -6,6 +6,10 @@
 
 typedef enum {
   OP_CONSTANT,
+  OP_ADD,
+  OP_SUBTRACT,
+  OP_MULTIPLY,
+  OP_DIVIDE,
   OP_NEGATE,
   OP_RETURN,
 } OpCode;
diff --git a/clox/src/debug.c b/clox/src/debug.c
index 91fe139..570bde9 100644
--- a/clox/src/debug.c
+++ b/clox/src/debug.c
@@ -36,6 +36,14 @@ int disassembleInstruction(Chunk *chunk, int offset) {
   switch (instruction) {
   case OP_CONSTANT:
     return constantInstruction("OP_CONSTANT", chunk, offset);
+  case OP_ADD:
+    return simpleInstruction("OP_ADD", offset);
+  case OP_SUBTRACT:
+    return simpleInstruction("OP_SUBTRACT", offset);
+  case OP_MULTIPLY:
+    return simpleInstruction("OP_MULTIPLY", offset);
+  case OP_DIVIDE:
+    return simpleInstruction("OP_DIVIDE", offset);
   case OP_NEGATE:
     return simpleInstruction("OP_NEGATE", offset);
   case OP_RETURN:
diff --git a/clox/src/main.c b/clox/src/main.c
index d2cb6bd..d1e747f 100644
--- a/clox/src/main.c
+++ b/clox/src/main.c
@@ -12,6 +12,18 @@ int main(int argc, const char *argv[]) {
   int constant = addConstant(&chunk, 1.2);
   writeChunk(&chunk, OP_CONSTANT, 123);
   writeChunk(&chunk, constant, 123);
+
+  constant = addConstant(&chunk, 3.4);
+  writeChunk(&chunk, OP_CONSTANT, 123);
+  writeChunk(&chunk, constant, 123);
+
+  writeChunk(&chunk, OP_ADD, 123);
+
+  constant = addConstant(&chunk, 5.6);
+  writeChunk(&chunk, OP_CONSTANT, 123);
+  writeChunk(&chunk, constant, 123);
+
+  writeChunk(&chunk, OP_DIVIDE, 123);
   writeChunk(&chunk, OP_NEGATE, 123);
 
   writeChunk(&chunk, OP_RETURN, 123);
diff --git a/clox/src/vm.c b/clox/src/vm.c
index e05a0c8..a775acb 100644
--- a/clox/src/vm.c
+++ b/clox/src/vm.c
@@ -25,6 +25,12 @@ Value pop() {
 static InterpretResult run() {
 #define READ_BYTE() (*vm.ip++)
 #define READ_CONSTANT() (vm.chunk->constants.values[READ_BYTE()])
+#define BINARY_OP(op)                                                          \
+  do {                                                                         \
+    double b = pop();                                                          \
+    double a = pop();                                                          \
+    push(a op b);                                                              \
+  } while (false)
 
   for (;;) {
 #ifdef DEBUG_TRACE_EXECUTION
@@ -45,6 +51,18 @@ static InterpretResult run() {
       push(constant);
       break;
     }
+    case OP_ADD:
+      BINARY_OP(+);
+      break;
+    case OP_SUBTRACT:
+      BINARY_OP(-);
+      break;
+    case OP_MULTIPLY:
+      BINARY_OP(*);
+      break;
+    case OP_DIVIDE:
+      BINARY_OP(/);
+      break;
     case OP_NEGATE:
       push(-pop());
       break;
@@ -58,6 +76,7 @@ static InterpretResult run() {
 
 #undef READ_BYTE
 #undef READ_CONSTANT
+#undef BINARY_OP
 }
 
 InterpretResult interpret(Chunk *chunk) {
-- 
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