From e619f7016feeaa572924b7efd6374abb9f6830f6 Mon Sep 17 00:00:00 2001
From: Patrick MARIE <pm@mkz.me>
Date: Sat, 24 Aug 2024 19:50:00 +0200
Subject: [PATCH] arithmetic calculator

---
 src/chunk.zig  |  5 +++++
 src/main.zig   | 16 +++++++++++++++-
 src/opcode.zig |  2 +-
 src/vm.zig     | 28 +++++++++++++++++++++++++---
 4 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/src/chunk.zig b/src/chunk.zig
index 2db5177..bb64175 100644
--- a/src/chunk.zig
+++ b/src/chunk.zig
@@ -77,6 +77,11 @@ pub const Chunk = struct {
 
         switch (instruction) {
             @intFromEnum(OpCode.OP_RETURN) => return utils.simple_instruction("OP_RETURN", offset),
+            @intFromEnum(OpCode.OP_ADD) => return utils.simple_instruction("OP_ADD", offset),
+            @intFromEnum(OpCode.OP_SUBSTRACT) => return utils.simple_instruction("OP_SUBSTRACT", offset),
+            @intFromEnum(OpCode.OP_MULTIPLY) => return utils.simple_instruction("OP_MULTIPLY", offset),
+            @intFromEnum(OpCode.OP_DIVIDE) => return utils.simple_instruction("OP_DIVIDE", offset),
+            @intFromEnum(OpCode.OP_NEGATE) => return utils.simple_instruction("OP_NEGATE", offset),
             @intFromEnum(OpCode.OP_CONSTANT) => return utils.constant_instruction("OP_CONSTANT", self, offset),
             else => {
                 debug.print("unknown opcode {d}\n", .{instruction});
diff --git a/src/main.zig b/src/main.zig
index f716e1f..76924a0 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -18,9 +18,23 @@ pub fn main() !void {
     var chunk = Chunk.new();
     try chunk.init(allocator);
 
-    const constant = try chunk.add_constant(allocator, 1.2);
+    var constant = try chunk.add_constant(allocator, 1.2);
     try chunk.write(allocator, @intFromEnum(OpCode.OP_CONSTANT), 123);
     try chunk.write(allocator, @intCast(constant), 123);
+
+    constant = try chunk.add_constant(allocator, 3.4);
+    try chunk.write(allocator, @intFromEnum(OpCode.OP_CONSTANT), 123);
+    try chunk.write(allocator, @intCast(constant), 123);
+
+    try chunk.write(allocator, @intFromEnum(OpCode.OP_ADD), 123);
+
+    constant = try chunk.add_constant(allocator, 5.6);
+    try chunk.write(allocator, @intFromEnum(OpCode.OP_CONSTANT), 123);
+    try chunk.write(allocator, @intCast(constant), 123);
+
+    try chunk.write(allocator, @intFromEnum(OpCode.OP_DIVIDE), 123);
+
+    try chunk.write(allocator, @intFromEnum(OpCode.OP_NEGATE), 123);
     try chunk.write(allocator, @intFromEnum(OpCode.OP_RETURN), 123);
 
     chunk.dissassemble("test chunk");
diff --git a/src/opcode.zig b/src/opcode.zig
index c99ab1b..44dac22 100644
--- a/src/opcode.zig
+++ b/src/opcode.zig
@@ -1 +1 @@
-pub const OpCode = enum(u8) { OP_CONSTANT, OP_RETURN };
+pub const OpCode = enum(u8) { OP_CONSTANT, OP_ADD, OP_SUBSTRACT, OP_MULTIPLY, OP_DIVIDE, OP_NEGATE, OP_RETURN };
diff --git a/src/vm.zig b/src/vm.zig
index bfc94ad..3547969 100644
--- a/src/vm.zig
+++ b/src/vm.zig
@@ -46,7 +46,7 @@ pub const VM = struct {
         while (true) {
             if (DEBUG_TRACE_EXECUTION) {
                 if (self.stack.items.len > 0) {
-                    debug.print("S:        ", .{});
+                    debug.print("{s:32}", .{""});
                     for (self.stack.items) |item| {
                         debug.print("[ ", .{});
                         print_value(item);
@@ -59,11 +59,18 @@ pub const VM = struct {
 
             const instruction = self.read_byte();
 
-            switch (instruction) {
+            try switch (instruction) {
                 @intFromEnum(OpCode.OP_CONSTANT) => {
                     const constant = self.read_constant();
                     try self.push(constant);
                 },
+                @intFromEnum(OpCode.OP_ADD) => self.binary_op(OpCode.OP_ADD),
+                @intFromEnum(OpCode.OP_SUBSTRACT) => self.binary_op(OpCode.OP_SUBSTRACT),
+                @intFromEnum(OpCode.OP_MULTIPLY) => self.binary_op(OpCode.OP_SUBSTRACT),
+                @intFromEnum(OpCode.OP_DIVIDE) => self.binary_op(OpCode.OP_SUBSTRACT),
+                @intFromEnum(OpCode.OP_NEGATE) => {
+                    try self.push(-self.pop());
+                },
                 @intFromEnum(OpCode.OP_RETURN) => {
                     print_value(self.pop());
                     return InterpretResult.OK;
@@ -72,7 +79,7 @@ pub const VM = struct {
                     debug.print("Invalid instruction: {d}\n", .{instruction});
                     return InterpretResult.RUNTIME_ERROR;
                 },
-            }
+            };
         }
 
         return InterpretResult.OK;
@@ -98,4 +105,19 @@ pub const VM = struct {
     pub fn pop(self: *VM) Value {
         return self.stack.pop();
     }
+
+    pub fn binary_op(self: *VM, op: OpCode) !void {
+        const b = self.pop();
+        const a = self.pop();
+
+        const res: Value = switch (op) {
+            OpCode.OP_ADD => a + b,
+            OpCode.OP_SUBSTRACT => a - b,
+            OpCode.OP_MULTIPLY => a * b,
+            OpCode.OP_DIVIDE => a / b,
+            else => unreachable,
+        };
+
+        try self.push(res);
+    }
 };