No parens in pack if not necessary.

Closes #321.

release.md

@@ -1,5 +1,6 @@
 ### Issue by Issue
 
+ * No parens in pack if not necessary. #321.
  * Rename Programmatic function to `$`. #320.
  * Convert pack sketch to a test. #319.
  * Convert signage sketch to a test. #318.

t/serialize/pack.t.js

@@ -1,4 +1,4 @@
-require('proof')(3, function (equal) {
+require('proof')(8, function (equal) {
     require('../..') // satisfy coverage
 
     function pack (bits, offset, size) {
@@ -7,18 +7,23 @@ require('proof')(3, function (equal) {
         mask = mask >>> bits - size
         shift = bits - offset - size
         mask = mask << shift >>> 0
-        if (shift) {
-            return '(value << ' + shift + ' & 0x' + mask.toString(16) + ') >>> 0'
-        } else {
-            return '(value & 0x' + mask.toString(16) + ') >>> 0'
-        }
+        var source = shift
+                   ? 'value << ' + shift + ' & 0x' + mask.toString(16)
+                   : 'value & 0x' + mask.toString(16)
+        return !offset && bits == 32 ? '(' + source + ') >>> 0' : source
     }
 
     var f = new Function('value', 'return ' + pack(16, 5, 7))
     equal(f(0x7f).toString(2), '11111110000', 'short')
     var f = new Function('value', 'return ' + pack(32, 0, 2))
-    equal(f(0x3).toString(2), '11000000000000000000000000000000', 'short')
-    console.log(pack(16, 13, 3))
+    equal(f(0x3).toString(2), '11000000000000000000000000000000', 'word left most')
+    equal(f(-1).toString(2), '11000000000000000000000000000000', 'word left most -1')
+    var f = new Function('value', 'return ' + pack(32, 1, 2))
+    equal(f(0x3).toString(2), '1100000000000000000000000000000', 'word')
     var f = new Function('value', 'return ' + pack(16, 13, 3))
     equal(f(0xff).toString(2), '111', 'no left shift')
+    var f = new Function('value', 'return ' + pack(32, 29, 3))
+    equal(f(0xff).toString(2), '111', 'no left shift 32')
+    equal(f(-1).toString(2), '111', 'no left shift 32 -1')
+    equal(f(-4).toString(2), '100', 'no left shift 32 -4')
 })