From 9286c148f601072dded92233a328a8867ff7ab0c Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Fri, 22 Oct 2021 12:24:10 +0200
Subject: Add a stack for our VM

---
 src/bytecode/vm.h | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

(limited to 'src/bytecode/vm.h')

diff --git a/src/bytecode/vm.h b/src/bytecode/vm.h
index d53fcf9..d9b37a3 100644
--- a/src/bytecode/vm.h
+++ b/src/bytecode/vm.h
@@ -7,9 +7,15 @@
 #include "ops.h"
 #include "debug.h"
 
+#define VM_STACK_CAP 1024
+
 typedef struct VM {
+    // Program code.
     Chunk *chunk;
+    // Program counter.
     u8 *pc;
+    // Stack.
+    Object *stack;
 } VM;
 
 VM vm_init(void);
@@ -21,12 +27,14 @@ vm_init(void) {
     VM vm = {
         .chunk = chunk_init(),
     };
+    array_init(vm.stack, VM_STACK_CAP);
     return vm;
 }
 
 void
 vm_free(VM vm) {
     chunk_free(vm.chunk);
+    array_free(vm.stack);
 }
 
 void
@@ -43,17 +51,26 @@ vm_interpret(VM vm) {
     u8 *last = vm.chunk->code + array_size(vm.chunk->code);
     while (vm.pc < last) {
 #ifdef DEBUG_TRACE_EXECUTION
-    disassemble_instruction(vm.chunk, (vm.pc - vm.chunk->code));
+        printf("stack:  [ ");
+        for (size_t i = 0; i < array_size(vm.stack); i++) {
+            display(vm.stack[i]);
+            if (i < array_size(vm.stack) - 1) {
+                printf(" | ");
+            }
+        }
+        printf(" ]\nop: ");
+        disassemble_instruction(vm.chunk, (vm.pc - vm.chunk->code));
 #endif
         u8 instruction = *vm.pc++;
         switch (instruction) {
             case OP_CONSTANT: {
                 u8 constant = *vm.pc++;
                 Object obj = vm.chunk->constants[constant];
-                display(obj);
-                printf("\n");
+                array_push(vm.stack, obj);
             } break;
             case OP_RETURN: {
+                display(array_pop(vm.stack));
+                printf("\n");
                 return;
             } break;
             default: {
-- 
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