Made a separate PDC_wscrl() function to scroll a window by 'n' lines …

…between rows 'top' and 'bottom'. This can be used by wscrl(), wdeleteln(), winsertln(), and winsdelln(), avoiding some redundant code. See preceding commit for the test program and following commit for the use of this function elsewhere.

pdcurses/scroll.c

@@ -40,20 +40,20 @@ scroll
 
 **man-end****************************************************************/
 
-int wscrl(WINDOW *win, int n)
+int PDC_wscrl(WINDOW *win, const int top, const int bottom, int n)
 {
     int start, end, n_lines;
     chtype blank, *tptr, *endptr;
 
     /* Check if window scrolls. Valid for window AND pad */
 
     assert( win);
-    if (!win || !win->_scroll || !n)
+    if (!win || !n)
         return ERR;
 
     blank = win->_bkgd;
-    start = win->_tmarg;
-    end = win->_bmarg + 1;
+    start = top;
+    end = bottom + 1;
     n_lines = end - start;
 
     if (n > 0)             /* scroll up */
@@ -71,7 +71,7 @@ int wscrl(WINDOW *win, int n)
             n = n_lines;
         memmove( win->_y[start + n], win->_y[start],
                      (n_lines - n) * win->_maxx * sizeof( chtype));
-        tptr = win->_y[win->_tmarg];
+        tptr = win->_y[top];
     }
 
         /* make blank lines */
@@ -81,11 +81,23 @@ int wscrl(WINDOW *win, int n)
         *tptr++ = blank;
 
     touchline(win, start, n_lines);
-
-    PDC_sync(win);
     return OK;
 }
 
+int wscrl(WINDOW *win, int n)
+{
+    int rval;
+
+    assert( win);
+    if (!win || !win->_scroll || !n)
+        rval = ERR;
+    else
+        rval = PDC_wscrl( win, win->_tmarg, win->_bmarg, n);
+    if( OK == rval)
+        PDC_sync( win);
+    return( rval);
+}
+
 int scrl(int n)
 {
     PDC_LOG(("scrl() - called\n"));