Initial code commit.

src/vm.h

@@ -0,0 +1,55 @@
+#ifndef FUN_VM_H
+#define FUN_VM_H
+
+#include "bytecode.h"
+
+#define VM_STACK_SIZE 1024
+#define VM_MAX_FRAMES 128
+#define VM_MAX_GLOBALS 128
+#define VM_OUTPUT_SIZE 1024
+#define FRAME_MAX_LOCALS 64
+
+static const char *opcode_names[] = {
+    "NOP","LOAD_CONST","LOAD_LOCAL","STORE_LOCAL",
+    "LOAD_GLOBAL","STORE_GLOBAL","ADD","SUB","MUL","DIV",
+    "LT","LTE","GT","GTE","EQ","NEQ","POP","JUMP",
+    "JUMP_IF_FALSE","CALL","RETURN","PRINT","HALT",
+    "MOD","AND","OR","NOT","DUP","SWAP"
+};
+
+typedef struct {
+    Bytecode *fn;
+    int ip;
+    Value locals[FRAME_MAX_LOCALS];
+} Frame;
+
+typedef struct {
+    Value stack[VM_STACK_SIZE];
+    int sp;
+
+    Frame frames[VM_MAX_FRAMES];
+    int fp; // frame pointer, -1 when no frame
+
+    Value globals[VM_MAX_GLOBALS];
+
+    Value output[VM_OUTPUT_SIZE]; // store printed values
+    int output_count;
+} VM;
+
+// initialize VM (zero state)
+void vm_init(VM *vm);
+
+// run entry Bytecode (pushes first frame)
+void vm_run(VM *vm, Bytecode *entry);
+
+// helper function to clear the output
+void vm_clear_output(VM *vm);
+
+void vm_free(VM *vm);
+
+static inline int opcode_is_valid(int op) {
+    return op >= OP_NOP && op <= OP_SWAP;  // all current opcodes
+}
+
+#endif
+