VM Chapter

include/chunk.h

@@ -7,6 +7,11 @@
 typedef enum {
     OP_CONSTANT_LONG,
     OP_CONSTANT,
+    OP_ADD,
+    OP_SUBTRACT,
+    OP_MULTIPLY,
+    OP_DIVIDE,
+    OP_NEGATE,
     OP_RETURN,
     OP_COUNT,
 }OpCode;

include/common.h

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

include/vm.h

@@ -2,13 +2,29 @@
 #define VM_INLCUDED
 
 #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,
+    INTERPRET_RESULT_COUNT,
+} InterpretResult;
+
 void initVM(void);
 void freeVM(void);
 
+InterpretResult interpret(Chunk *chunk);
+void push(Value value);
+Value pop();
+
 #endif

src/debug.c

@@ -43,10 +43,19 @@ int disassembleInstruction(Chunk *chunk, int offset){
     switch(instruction){
         case OP_CONSTANT:
             return constantInstruction("OP_CONSTANT", chunk,offset);
-
         case OP_CONSTANT_LONG:
             return longConstantInstruction("OP_CONSTANT_LONG", chunk, offset);
+        case OP_ADD:
+            return simpleInstruction("OP_ADD", offset);
+        case OP_SUBTRACT:
+            return simpleInstruction("OP_SUBTRACT", offset);
+        case OP_MULTIPLY:
+            return simpleInstruction("OP_MULTIPLY", offset);
+        case OP_DIVIDE:
+            return simpleInstruction("OP_DIVIDE", offset);
 
+        case OP_NEGATE:
+            return simpleInstruction("OP_NEGATE", offset);
         case OP_RETURN:
             return simpleInstruction("OP_RETURN",offset);
         default:

src/vm.c

@@ -1,11 +1,75 @@
 #include "../include/common.h"
 #include "../include/vm.h"
+#include "../include/debug.h"
+#include <stdio.h>
 
-
+VM vm;
+static void resetStack(void){
+    vm.stackTop = vm.stack;
+}
 void initVM(void){
-
+    resetStack();
 }
 void freeVM(void){
 
 }
+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()])    
+#define BINARY_OP(op) \
+    do{ \
+    double b = pop(); \
+    double a = pop(); \
+    push(a op b); \
+    } while (false)
+    for(;;){
+#ifndef 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_ADD:         BINARY_OP(+); break;                    
+            case OP_SUBTRACT:    BINARY_OP(-); break;                    
+            case OP_MULTIPLY:    BINARY_OP(*); break;                    
+            case OP_DIVIDE:    BINARY_OP(/); break;                    
+            case OP_NEGATE: push(-pop()); break;
+            case OP_RETURN: {
+                                printValue(pop());
+                                printf("\n");
+                                return INTERPRET_OK;          
+                            }
+        }
+    }
+#undef BINARY_OP
+#undef READ_CONSTANT
+#undef READ_BYTE
+}
+
+InterpretResult interpret(Chunk *chunk){
+    vm.chunk = chunk;
+    vm.ip = vm.chunk->code;
+    return run();
+}
 

tests/01_main.c

@@ -9,12 +9,23 @@ int main(void){
     Chunk chunk;
     initChunk(&chunk);
  
-    int constant = addConstant(&chunk,1.2);
-    writeChunk(&chunk, OP_CONSTANT,10);
-    writeChunk(&chunk,constant,10); 
- //   writeChunk(&chunk, OP_RETURN,10);
+    int constant = addConstant(&chunk,1.25);
+    writeChunk(&chunk, OP_CONSTANT,1);
+    writeChunk(&chunk,constant,1);
+
+
+
+    constant = addConstant(&chunk,10);
+    writeChunk(&chunk, OP_CONSTANT,2);
+    writeChunk(&chunk,constant,2);
+
+
+    writeChunk(&chunk, OP_DIVIDE, 3);
+    writeChunk(&chunk, OP_RETURN,5);
 
     disassembleChunk(&chunk,"Test Chunk");
+    int res = interpret(&chunk);
+    (void) res;
     freeVM();
     freeChunk(&chunk);