add comments explaining extended parsing.

lib/tput.js

@@ -213,24 +213,25 @@ Tput.prototype.parseTerminfo = function(data) {
 //      lastStrTableOffset: 680,
 //      total: 245 },
 
-// For xterm, offsets:
-// { header: '0 - 10',
-//   bools: '10 - 12',
-//   numbers: '12 - 14',
+// For xterm, layout:
+// { header: '0 - 10', // length: 10
+//   bools: '10 - 12', // length: 2
+//   numbers: '12 - 14', // length: 2
 //   strings: '14 - 128', // length: 114 (57 short)
-//   symstrings: '128 - 248', // length: 120 (60 short)
-//   stringData: '248 - 612',
-//   sym: '612 - 928' }
+//   symoffsets: '128 - 248', // length: 120 (60 short)
+//   stringtable: '248 - 612', // length: 364
+//   sym: '612 - 928' } // length: 316
 //
-// header size: 10
-// bools size: 2
-// numbers size: 4
-// string-offset size: 114
-// sym-offset size: 120
-// string table size: 364
-// sym size: 316
-// 364 + 316 === 680 (lastStrTableOffset)
-// data.length - h.lastStrTableOffset === 248 (sym-offset size)
+// How lastStrTableOffset works:
+//   data.length - h.lastStrTableOffset === 248 (sym-offset end, string-table start)
+//   364 + 316 === 680 (lastStrTableOffset)
+// How strTableSize works:
+//   h.strCount + [symOffsetCount] === h.strTableSize
+//   57 + 60 === 117 (strTableSize)
+//   symOffsetCount doesn't actually exist in the header. it's just implied.
+// Getting the number of sym offsets:
+//   h.symOffsetCount = h.strTableSize - h.strCount;
+//   h.symOffsetSize = (h.strTableSize - h.strCount) * 2;
 
 Tput.prototype.parseExtended = function(data) {
   var info = {}
@@ -247,6 +248,8 @@ Tput.prototype.parseExtended = function(data) {
     lastStrTableOffset: (data[i + 9] << 8) | data[i + 8]
   };
 
+  // h.symOffsetCount = h.strTableSize - h.strCount;
+
   h.total = h.headerSize
     + h.boolCount
     + h.numCount * 2
@@ -294,6 +297,7 @@ Tput.prototype.parseExtended = function(data) {
 
   // Pass over the sym offsets and get to the string table.
   i = data.length - h.lastStrTableOffset;
+  // i += h.symOffsetCount * 2;
 
   // String Table
   var high = 0;
@@ -328,7 +332,7 @@ Tput.prototype.parseExtended = function(data) {
   l = data.length;
 
   var sym = []
-    , j = 0;
+    , j;
 
   for (; i < l; i++) {
     j = i;