refactor: setup infrastructure of the new architecture (call stack, stack frames) in the vm

Author: aymaneelmaini

src/vm.c

@@ -17,6 +17,7 @@ VM vm;
 static void reset_stack()
 {
     vm.stack_top = vm.stack;
+    vm.frame_count = 0;
 }
 
 static void runtime_error(const char* format, ...)
@@ -27,8 +28,9 @@ static void runtime_error(const char* format, ...)
     va_end(args);
     fputs("\n", stderr);
 
-    size_t instruction = vm.ip - vm.chunk->code - 1;
-    int    line = vm.chunk->lines[instruction];
+    CallFrame* frame = &vm.frames[vm.frame_count - 1];
+    size_t     instruction = frame->ip - frame->function->chunk.code - 1;
+    int        line = frame->function->chunk.lines[instruction];
     fprintf(stderr, "[Line %d] in script\n", line);
 
     reset_stack();
@@ -88,9 +90,11 @@ static void concatenate()
 
 static InterpretResult run()
 {
-#define READ_BYTE() (*vm.ip++)
-#define READ_CONSTANT() (vm.chunk->constants.values[READ_BYTE()])
-#define READ_SHORT() (vm.ip += 2, (u16)(vm.ip[-2] << 8) | vm.ip[-1])
+    CallFrame* frame = &vm.frames[vm.frame_count - 1];
+
+#define READ_BYTE() (*frame->ip++)
+#define READ_SHORT() (frame->ip += 2, (u16)(frame->ip[-2] << 8) | frame->ip[-1])
+#define READ_CONSTANT() (frame->function->chunk.constants.values[READ_BYTE()])
 #define READ_STRING() AS_STRING(READ_CONSTANT())
 #define BINARY_OP(value_type, op)                                              \
     do                                                                         \
@@ -116,7 +120,8 @@ static InterpretResult run()
             printf(" ]");
         }
         printf("\n");
-        disassemble_instruction(vm.chunk, (int)(vm.ip - vm.chunk->code));
+        disassemble_instruction(&frame->function->chunk,
+                                (int)(frame->ip - frame->function->chunk.code));
 #endif
         u8 instruction;
         switch (instruction = READ_BYTE())
@@ -142,13 +147,13 @@ static InterpretResult run()
         case OP_GET_LOCAL:
         {
             u8 slot = READ_BYTE();
-            push(vm.stack[slot]);
+            push(frame->slots[slot]);
             break;
         }
         case OP_SET_LOCAL:
         {
             u8 slot = READ_BYTE();
-            vm.stack[slot] = peek(0);
+            frame->slots[slot] = peek(0);
             break;
         }
         case OP_GET_GLOBAL:
@@ -241,20 +246,20 @@ static InterpretResult run()
         case OP_JUMP:
         {
             u16 offset = READ_SHORT();
-            vm.ip += offset;
+            frame->ip += offset;
             break;
         }
         case OP_JUMP_IF_FALSE:
         {
             u16 offset = READ_SHORT();
             if (is_falsey(peek(0)))
-                vm.ip += offset;
+                frame->ip += offset;
             break;
         }
         case OP_LOOP:
         {
             u16 offset = READ_SHORT();
-            vm.ip -= offset;
+            frame->ip -= offset;
             break;
         }
         case OP_RETURN:
@@ -274,17 +279,15 @@ InterpretResult interpret(char* source)
     Chunk chunk;
     init_chunk(&chunk);
 
-    if (!compile(source, &chunk))
-    {
-        free_chunk(&chunk);
+    ObjFunction* function = compile(source, &chunk);
+    if (function == NULL)
         return INTERPRET_COMPILE_ERROR;
-    }
-
-    vm.chunk = &chunk;
-    vm.ip = vm.chunk->code;
 
-    InterpretResult result = run();
+    push(OBJ_VAL(function));
+    CallFrame* frame = &vm.frames[vm.frame_count++];
+    frame->function = function;
+    frame->ip = function->chunk.code;
+    frame->slots = vm.stack;
 
-    free_chunk(&chunk);
-    return result;
+    return run();
 }

src/vm.h

@@ -3,20 +3,29 @@
 
 #include "chunk.h"
 #include "common.h"
+#include "object.h"
 #include "table.h"
 #include "value.h"
 
-#define STACK_MAX 256
+#define FRAMES_MAX 64
+#define STACK_MAX (FRAMES_MAX * UINT8_COUNT)
 
 typedef struct
 {
-    Chunk* chunk;
-    u8*    ip;  // aka of Instrction Pointer
-    Value  stack[STACK_MAX];
-    Value* stack_top;
-    Table  globals;
-    Table  strings;  // for string interning just like (string pool in java)
-    Obj*   objects;
+    ObjFunction* function;
+    u8*          ip;
+    Value*       slots;
+} CallFrame;
+
+typedef struct
+{
+    CallFrame frames[FRAMES_MAX];
+    int       frame_count;
+    Value     stack[STACK_MAX];
+    Value*    stack_top;
+    Table     globals;
+    Table     strings;  // for string interning just like (string pool in java)
+    Obj*      objects;
 } VM;
 
 typedef enum