diff --git a/oblong b/oblong
new file mode 100755
index 0000000..80c79ae
Binary files /dev/null and b/oblong differ
diff --git a/oblong.c b/oblong.c
index 9499d0e..c0543c2 100644
--- a/oblong.c
+++ b/oblong.c
@@ -301,8 +301,8 @@ void procargs ( int nargs , char ** arg ) // int nargs =2 for [oblong -f] **arg
     if ( !numreplications ) numreplications = 1 ; 
     if ( maxram > 0 ) {
       fprintf ( stderr , "\nUsing %.2f MBytes of RAM for matrix buffers\n" , maxram ) ;
-        fflush ( stderr ) ; //清空缓存区 *** 
-        maxram *= 1024 * 1024 ; } // ***
+        fflush ( stderr ) ; //清空缓存区 
+        maxram *= 1024 * 1024 ; } // maxram = maxram * 1024 * 1024;
     reportheader = '\r' ;
     if ( !isatty( fileno( stderr ) ) ) {
         errout ( verbose , "Verbose allowed only when STDERR goes to screen" ) ; 
@@ -318,10 +318,10 @@ void procargs ( int nargs , char ** arg ) // int nargs =2 for [oblong -f] **arg
 
 void init_bit_counters ( void )
 {
-    int a , b , c ;
-    for ( a = 0 ; a < 65536 ; ++ a ) {
-      for ( b = 1 , c = 0 ; b <= a ; b <<= 1 ) 
-        if ( ( b & a ) ) ++ c ; 
+    int a , b , c ; // bitct[65536]
+    for ( a = 0 ; a < 65536 ; ++ a ) { // a 0 -> 65535 
+      for ( b = 1 , c = 0 ; b <= a ; b <<= 1 ) // <= 是 < 或 =; 
+        if ( ( b & a ) ) ++ c ; // c++; 
       bitct [ a ] = c ; }
 }        
 
@@ -848,10 +848,10 @@ void read_input ( void )
     char c ; 
     double prop , secs , prevprop ;
     clock_t beg , end ;
-    strcpy ( nampt , " " ) ;
-    if ( treeinp != NULL ) {
-        while ( strcmp ( nampt , "tread" ) && !feof ( treeinp ) ) 
-           fscanf ( treeinp , " %7s" , nampt ) ;
+    strcpy ( nampt , " " ) ; // nampt = " "
+    if ( treeinp != NULL ) { // int is NULL (L34), but can specific the tree file (L273)
+        while ( strcmp ( nampt , "tread" ) && !feof ( treeinp ) ) //feof 如果 EOF 返回非 0，没有EOF 返回 0， strcmp 0 相同，非0 则执行，即 非 tread 并且 没有 EOF 且执行
+           fscanf ( treeinp , " %7s" , nampt ) ; // 输入长度为 7 的 string
         errout ( feof ( treeinp ) , "String \"tread\" not found in tree file" ) ;
         fscanf ( treeinp , " %c" , &c ) ;
         errout ( c != 39 , "Number of trees should be indicated in the title of tree-file" ) ;