This whole "strings" thing isn't quite working...

src/c0vm.js

@@ -394,10 +394,16 @@ ProgramState.prototype.step = function() {
         // Read offset into an array
         var elt_index = this.pop();
         var index = this.pop();
-        var array_length = this.heap[index];
-        var elt_size = this.heap[index+1];
-        if (elt_index >= array_length) c0_memory_error("Array index out of bounds.");
-        this.push(index + 2 + (elt_size*elt_index));
+
+        if (typeof index == "string") {
+            this.push(index.slice(elt_index));
+        } else {
+            var array_length = this.heap[index];
+            var elt_size = this.heap[index+1];
+            if (elt_index >= array_length)
+                c0_memory_error("Array index out of bounds.");
+            this.push(index + 2 + (elt_size*elt_index));
+        }
         this.frame.pc++;
         break;
 
@@ -438,7 +444,10 @@ ProgramState.prototype.step = function() {
 
     case op.CMLOAD:
         var addr = this.pop();
-        this.push(this.heap[addr]);
+        if (typeof addr == "string")
+            this.push(addr);
+        else
+            this.push(this.heap[addr]);
         this.frame.pc++;
         break;
 

test/strings.c0.bc0

@@ -109,10 +109,10 @@ B0       # return          #
 
 00 06             # native count
 # native pool
-00 01 00 47       # char_ord
-00 01 00 46       # char_chr
-00 01 00 50       # string_length
-00 01 00 53       # string_to_chararray
-00 01 00 4B       # string_from_chararray
-00 01 00 06       # print
+00 01 00 51       # char_ord
+00 01 00 50       # char_chr
+00 01 00 5A       # string_length
+00 01 00 5D       # string_to_chararray
+00 01 00 55       # string_from_chararray
+00 01 00 10       # print
 

test/tests.js

@@ -20,6 +20,30 @@ callbacks[c0ffi.NATIVE_PRINTLN] = function(args) {
     return 0;
 }
 
+callbacks[c0ffi.NATIVE_STRING_LENGTH] = function(args) {
+    return args[0].length;
+}
+
+callbacks[c0ffi.NATIVE_STRING_TO_CHARARRAY] = function(args) {
+    return args[0];
+}
+
+callbacks[c0ffi.NATIVE_STRING_FROM_CHARARRAY] = function(args) {
+    console.log("string_from_chararray: " + args);
+    return args[0];
+}
+
+callbacks[c0ffi.NATIVE_CHAR_CHR] = function(args) {
+    return String.fromCharCode(args[0]);
+}
+
+callbacks[c0ffi.NATIVE_CHAR_ORD] = function(args) {
+    console.log("native_car_ord: " + args);
+    if (typeof args[0] == "string")
+        return args[0].charCodeAt(0);
+    return args[0];
+}
+
 function doTest(filename, expected_result) {
     return function(test) {
         var result = c0vm.execute(parser.parse(filename), callbacks, false);
@@ -98,3 +122,14 @@ exports.testArith = function(test) {
             printout);
     test.done();
 }
+
+exports.testPIAZZA1 = doTest("piazza1.c0.bc0", 18);
+
+exports.testSTRINGS = function(test) {
+    printout = "";
+    var result = c0vm.execute(parser.parse("strings.c0.bc0"), callbacks, false);
+    test.ok(printout == "hello there!?",
+            "strings.c0.bc0 - Did not print to screen correctly, result was " + 
+            printout);
+    test.done();
+}