Added arithmetic and control flow functions.

It passes very simple test files.

src/c0vm.js

@@ -3,6 +3,15 @@ pc = 0;
 program = [];
 variables = [];
 
+function doIf(shouldJump) {
+    if (shouldJump) {
+        var address_offset = (program[pc+1] * 0x1000) + program[pc+2];
+        pc += address_offset;
+    } else {
+        pc += 3;
+    }
+}
+
 // Takes in a parsed .bc0 file and runs it
 function execute(file) {
     console.log("Beginning execution of file " + file);
@@ -33,7 +42,12 @@ function execute(file) {
             break;
         case BIPUSH:
             pc += 2;
-            stack.push(program[pc-1]);
+            var val = program[pc-1];
+
+            // Do sign extension if necessary
+            if (val & 0x80 != 0)
+                val = -0x80 + (val & 0x7F);
+            stack.push(val);
             break;
 
             // Returning from a function
@@ -47,19 +61,147 @@ function execute(file) {
             var y = stack.pop();
             var x = stack.pop();
             console.log("Adding " + x + " and " + y);
-            stack.push((x+y) % 0x100);
+            stack.push((x+y) % 0x100000000);
             break;
         case ISUB:
             pc++;
             var y = stack.pop();
             var x = stack.pop();
-            stack.push((x-y) % 0x100);
+            stack.push((x-y) % 0x100000000);
             break;
         case IMUL:
             pc++;
             var y = stack.pop();
             var x = stack.pop();
-            stack.push((x*y) % 0x100);
+            stack.push((x*y) % 0x100000000);
+            break;
+        case IDIV:
+            pc++;
+            var y = stack.pop();
+            var x = stack.pop();
+            if (y == 0) c0_arith_error("Divide by zero");
+            if (x == INT_MIN && y == -1) c0_arith_error("Arithmetic overflow");
+
+            // This does int division.
+            // As I understand it, the ~~ is treated as the identity on integers
+            // which forces the type to int, not float
+            stack.push(~~(x/y));
+            break;
+        case IREM:
+            pc++;
+            var y = stack.pop();
+            var x = stack.pop();
+            if (y == 0) c0_arith_error("Divide by zero");
+            if (x == INT_MIN && y == -1) c0_arith_error("Arithmetic overflow");
+            stack.push(x%y);
+            break;
+        case IAND:
+            pc++;
+            var y = stack.pop();
+            var x = stack.pop();
+            stack.push(x&y);
+            break;
+        case IOR:
+            pc++;
+            var y = stack.pop();
+            var x = stack.pop();
+            stack.push(x|y);
+            break;
+        case IXOR:
+            pc++;
+            var y = stack.pop();
+            var x = stack.pop();
+            stack.push(x^y);
+            break;
+        case ISHL:
+            pc++;
+            var y = stack.pop();
+            var x = stack.pop();
+            if (y < 0 || y > 31) c0_arith_error("Shifting by too many bits");
+            stack.push(x<<y);
+            break;
+        case ISHR:
+            pc++;
+            var y = stack.pop();
+            var x = stack.pop();
+            if (y < 0 || y > 31) c0_arith_error("Shifting by too many bits");
+            stack.push(x>>y);
+            break;
+
+            // Operations on local variables
+
+        case VLOAD:
+            pc += 2;
+            var index = program[pc-1];
+            stack.push(variables[index]);
+            break;
+        case VSTORE:
+            pc +=2 ;
+            var index = program[pc-1];
+            variables[index] = stack.pop();
+            break;
+        case ACONST_NULL:
+            pc++;
+            stack.push(0);
+            break;
+        case ILDC:
+            pc += 3;
+            var c1 = program[pc-2];
+            var c2 = program[pc-1];
+            var index = (c1 * 0x1000) + c2;
+
+            stack.push(file.int_pool[index]);
+            break;
+        case ALDC:
+            console.log("Error: I don't know how to handle ALDC yet");
+            return;
+
+            // Control flow
+        case NOP:
+            pc++;
+            break;
+        case IF_CMPEQ:
+            var y = stack.pop();
+            var x = stack.pop();
+            doIf(y == x);
+            break;
+        case IF_CMPNE:
+            var y = stack.pop();
+            var x = stack.pop();
+            doIf(y != x);
+            break;
+        case IF_CMPLT:
+            var y = stack.pop();
+            var x = stack.pop();
+            doIf(y > x);
+            break;
+        case IF_CMPGE:
+            var y = stack.pop();
+            var x = stack.pop();
+            doIf(y <= x);
+            break;
+        case IF_CMPGT:
+            var y = stack.pop();
+            var x = stack.pop();
+            doIf(y < x);
+            break;
+        case IF_CMPLE:
+            var y = stack.pop();
+            var x = stack.pop();
+            doIf(y >= x);
+            break;
+        case GOTO:
+            doIf(true);
+            break;
+        case ATHROW:
+            pc++;
+            c0_user_error(stack.pop());
+            break;
+        case ASSERT:
+            pc++;
+            var a = stack.pop();
+            if (stack.pop() == 0)
+                c0_assertion_failure(a);
             break;
 
         default: