add vm

src/'

@@ -0,0 +1,47 @@
+#include "common.h"
+#include "vm.h"
+
+VM vm; 
+
+void newVM() {
+
+}
+
+void freeVM() {
+
+}
+
+static InterpretResult run() {
+#define READ_BYTE() (*vm.ip++)
+#define READ_CONSTANT() (vm.chunk->constants.values[READ_BYTE()])
+
+  for (;;) {
+#ifdef DEBUG_TRACE_EXECUTION
+    disassembleInstruction(vm.chunk,
+                           (int)(vm.ip - vm.chunk->code));
+#endif
+
+    uint8_t instruction;
+    switch (instruction = READ_BYTE()) {
+      case OP_CONSTANT: {
+        Value constant = READ_CONSTANT();
+        printValue(constant);
+        printf("\n");
+        break;
+      }
+      case OP_RETURN: {
+        return INTERPRET_OK;
+      }
+    }
+  }
+
+#undef READ_BYTE
+#undef READ_CONSTANT
+}
+
+InterpretResult interpret(Chunk* chunk) {
+  vm.chunk = chunk;
+  vm.ip = vm.chunk->code;
+  return run();
+}
+

src/common.h

@@ -5,4 +5,6 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#define DEBUG_TRACE_EXECUTION
+
 #endif

src/main.c

@@ -1,8 +1,11 @@
 #include "common.h"
 #include "chunk.h"
 #include "debug.h"
+#include "vm.h"
 
 int main(int argc, const char** argv) {
+  newVM();
+  
   Chunk chunk;
   newChunk(&chunk);
 
@@ -13,6 +16,7 @@ int main(int argc, const char** argv) {
   writeChunk(&chunk, OP_RETURN, 1);
 
   disassembleChunk(&chunk, "test chunk");
+  freeVM();
   freeChunk(&chunk);
   return 0;
 }

src/vm.c

@@ -0,0 +1,72 @@
+#include "common.h"
+#include "debug.h"
+#include "vm.h"
+
+#include <stdio.h>
+
+VM vm; 
+
+static void resetStack() {
+  vm.stackTop = vm.stack;
+}
+
+void newVM() {
+  resetStack();
+}
+
+void freeVM() {
+
+}
+
+void push(Value value) {
+  *vm.stackTop = value;
+  vm.stackTop++;
+}
+
+Value pop() {
+  vm.stackTop--;
+  return *vm.stackTop;
+}
+
+static InterpretResult run() {
+#define READ_BYTE() (*vm.ip++)
+#define READ_CONSTANT() (vm.chunk->constants.values[READ_BYTE()])
+
+  for (;;) {
+#ifdef DEBUG_TRACE_EXECUTION
+    printf("          ");
+    for (Value* slot = vm.stack; slot < vm.stackTop; slot++) {
+      printf("[ ");
+      printValue(*slot);
+      printf(" ]");
+    }
+    printf("\n");
+    disassembleInstruction(vm.chunk,
+                           (int)(vm.ip - vm.chunk->code));
+#endif
+
+    uint8_t instruction;
+    switch (instruction = READ_BYTE()) {
+      case OP_CONSTANT: {
+        Value constant = READ_CONSTANT();
+	push(constant);
+        break;
+      }
+      case OP_RETURN: {
+	printValue(pop());
+	printf("\n");
+        return INTERPRET_OK;
+      }
+    }
+  }
+
+#undef READ_BYTE
+#undef READ_CONSTANT
+}
+
+InterpretResult interpret(Chunk* chunk) {
+  vm.chunk = chunk;
+  vm.ip = vm.chunk->code;
+  return run();
+}
+

src/vm.h

@@ -0,0 +1,29 @@
+#ifndef ztl_vm_h
+#define ztl_vm_h
+
+#include "chunk.h"
+#include "value.h"
+
+#define STACK_MAX 256
+
+typedef struct {
+  Chunk *chunk;
+  uint8_t *ip;
+  Value stack[STACK_MAX];
+  Value *stackTop;
+} VM;
+
+typedef enum {
+  INTERPRET_OK,
+  INTERPRET_COMPILE_ERROR,
+  INTERPRET_RUNTIME_ERROR
+} InterpretResult;
+
+void newVM();
+void freeVM();
+InterpretResult interpret(Chunk *chunk);
+void push(Value value);
+Value pop();
+
+#endif
+