From f0cd7a3cab56a6f8d7b4520aaa168a271a94d6d4 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Wed, 27 Oct 2021 10:43:30 +0200
Subject: Add initial implementation of locals

---
 src/bytecode/vm.h | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

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

diff --git a/src/bytecode/vm.h b/src/bytecode/vm.h
index 3f59aff..84d2432 100755
--- a/src/bytecode/vm.h
+++ b/src/bytecode/vm.h
@@ -183,6 +183,11 @@ vm_interpret(VM *vm) {
                 Object obj = frame->chunk->constants[constant];
                 array_push(vm->stack, obj);
             } break;
+            case OP_DEF_LOCAL: {
+                Object value = array_pop(vm->stack);
+                ssize_t idx = AS_FIXNUM(array_pop(vm->stack));
+                vm->stack[frame->stack_offset + idx] = value;
+            } break;
             case OP_DEF: {
                 Object value = array_pop(vm->stack);
                 Object name = array_pop(vm->stack);
@@ -281,12 +286,15 @@ vm_interpret(VM *vm) {
                 } else if (n_args > n_params) {
                     RUNTIME_ERROR(ERR_TOO_MANY_ARGS);
                 }
+                ssize_t n_locals = array_size(proc.chunk->locals) - n_params;
 
-                // DEBUG:...
-                // disassemble_chunk(proc.chunk);
+#ifdef DEBUG
+                disassemble_chunk(proc.chunk);
+#endif
 
                 // Tail-call optimization.
                 if (proc.chunk != frame->chunk || *vm->pc != OP_RETURN) {
+                    // Prepare new call frame.
                     CallFrame new_frame = (CallFrame){
                         .chunk = proc.chunk,
                         .rp = vm->pc,
@@ -294,14 +302,20 @@ vm_interpret(VM *vm) {
                     };
                     array_push(vm->frames, new_frame);
                     frame = &vm->frames[array_size(vm->frames) - 1];
+
+                    // Prepare local slots.
+                    for (ssize_t i = 0; i < n_locals; i++) {
+                        array_push(vm->stack, NIL_VAL);
+                    }
                 } else {
                     // Bind tail-call parameters.
-                    for (size_t i = 0; i < (size_t)n_params; i++) {
-                        Object obj = array_peek(vm->stack, n_params - 1 - i);
+                    for (ssize_t i = 0; i < n_params; i++) {
+                        Object obj = array_peek(vm->stack, n_locals + n_params - 1 - i);
                         vm->stack[frame->stack_offset + i] = obj;
                     }
+
                     // Reset stack size.
-                    array_head(vm->stack)->size = frame->stack_offset + n_params;
+                    array_head(vm->stack)->size = frame->stack_offset + n_params + n_locals;
                 }
                 vm->pc = frame->chunk->code;
             } break;
-- 
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