[js] Serialize variable length integers up to 32bit.

Add a unit test for that.

src/vm/js/bin/run_tests

@@ -1,3 +1,4 @@
 #!/bin/bash
 # 19 and 30 where moved out as they were parrot specific, 52,54 is missing, we can't pass 49 till we are bootstraped
+prove -e 'node' t/js/varint.js # unit tests for the js runtime
 prove "$@" -e  './nqp-js' gen/js/qregex.t t/nqp/{01,02,03,04,05,06,07,08,09,10,11,12,13,14,15,16,17,18,19,20,21,22,23,25,26,27,28,31,32,33,34,35,36,37,38,39,40,41,42,44,45,46,47,48,50,51,53,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,83,84,88,89,90,91,92,93,94,95,96}*.t t/js/getcomp-js.t t/qast/02* t/serialization/02-types.t 

src/vm/js/nqp-runtime/serialization.js

@@ -67,6 +67,7 @@ BinaryWriteCursor.prototype.varint = function(value) {
             storage_needed = 4;
         else if (abs_val <= 0x00000007FFFFFFFF)
             storage_needed = 5;
+        else console.log("TODO serializing bigger integers");
 
         /* TODO bigger numbers */
         /*else if (abs_val <= 0x000007FFFFFFFFFFLL)
@@ -94,8 +95,10 @@ BinaryWriteCursor.prototype.varint = function(value) {
                || (nybble >> 3) == ~0);
 
         this.I8((rest << 4) | (nybble & 0xF));
-        console.log("TODO - writing varints that take 2-8 bytes", value, storage_needed);
-        //memcpy(buffer + offset, &value, rest);
+
+        this.growToHold(rest);
+        this.buffer.writeIntLE(value, this.offset, rest, true);
+        this.offset += rest;
     }
 };
 

t/js/varint.js

@@ -0,0 +1,37 @@
+var tap = require('tap');
+var BinaryWriteCursor = require('nqp-runtime/serialization').BinaryWriteCursor;
+var BinaryCursor = require('nqp-runtime/deserialization').BinaryCursor;
+
+
+function check(n, expected) {
+  expected = new Buffer(expected);
+  var cursor = new BinaryWriteCursor(null);
+  cursor.varint(n);
+  var got = cursor.buffer.slice(0, cursor.offset);
+
+  var correct = got.equals(expected);
+  tap.ok(correct, "writing " + n);
+
+  if (!correct) {
+    tap.comment("got", got);
+    tap.comment("expected", expected);
+  }
+
+
+  var reader = new BinaryCursor(expected, 0, null, null);
+
+  var got_n = reader.varint();
+
+  tap.equal(got_n, n, "reading "+n);
+}
+
+check(-1, [128]);
+check(0, [129]);
+check(1, [130]);
+check(30, [159]);
+check(126, [255]);
+check(200, [16,200]);
+check(-200, [31,56]);
+check(10000, [32,16,39]);
+check(-10000, [47,240,216]);
+check(1000000, [48,64,66,15]);