--- a/src/parallel_execution/generate_stub.pl	Sat Jan 28 15:48:54 2017 +0900
+++ b/src/parallel_execution/generate_stub.pl	Sat Jan 28 16:04:38 2017 +0900
@@ -161,11 +161,13 @@
                 my $args = $2;
                 my $tail = $3;
                 if ($codeGearName =~ /_stub$/) {
+                    # don't touch already existing stub
                     $stub{$codeGearName} = 1;
                     print $fd $_;
                     next;
                 }
                 if (defined $prevCodeGearName) {
+                    # stub is generated just before next CodeGear
                     if (defined $stub{$prevCodeGearName."_stub"}) {
                         undef $prevCodeGearName;
                         print $fd $_;
@@ -173,6 +175,11 @@
                     }
                     $stub{$prevCodeGearName."_stub"} = &generateStub($fd,$prevCodeGearName,$dataGearName{$prevCodeGearName});
                 }
+                # analyzing CodeGear argument
+                #      these arguments are extract from current context's arugment DataGear Interface
+                #      and passed to the CodeGear
+                #      struct Implementaion needs special handling
+                #      __code next(...)   --->   enum Code next
                 $prevCodeGearName = $codeGearName;
                 $dataGearVar{$codeGearName} = [];
                 $outputVar{$codeGearName} = "";
@@ -182,13 +189,16 @@
                     if ($args =~ s/(^\s*,\s*)//) {
                         $newArgs .= $1;
                     }
-                    # replace __code next
+                    # continuation case
                     if ($args =~ s/^\_\_code\s+(\w+)\(([^)]*)\)//) {
                         my $next = $1;
                         my @args = split(/,/,$2);
                         if ( &generateStubArgs($codeGearName, $next, "Code", $next, $interface,0) ) {
                             $newArgs .= "enum Code $next";
                         }
+                        # analyze continuation arguments
+                        #    output arguments are defined in the Interface take the pointer of these
+                        #    output arguments are put into the Interface DataGear just before the goto
                         for my $arg (@args) {
                             $arg =~ s/^\s*//;
                             last if ($arg =~ /\.\.\./);
@@ -216,21 +226,25 @@
                         last;
                     }
                 }
+                # generate goto statement from stub to the CodeGear in the buffer
                 $dataGearName{$codeGearName} .= "\tgoto $codeGearName(context";
                 for my $arg ( @{$dataGearVar{$codeGearName}}) {
                     $dataGearName{$codeGearName} .= ", $arg";
                 }
                 $dataGearName{$codeGearName} .= ");";
+                # generate CodeGear header with new arguments
                 print $fd "__code $codeGearName($newArgs)$tail\n";
                 if ($outputVar{$codeGearName} ne "") {
                     print $fd $outputVar{$codeGearName};
                 }
                 next;
             } elsif (/^(.*)goto (\w+)\((.*)\);/) {
+                # handling got statement  
+                # convert it to the meta call form with two arugments, that is context and enum Code
                 my $prev = $1;
                 my $next = $2;
                 my @args = split(/,/,$3);
-                # write continuation's arguments
+                # write continuation's arguments into the interface arguments
                 # we may need a commit for a shared DataGear
                 for my $arg ( @{$outputArgs{$codeGearName}->{$next}} ) {
                     my $v = shift(@args);