1 files changed, 85 insertions, 3 deletions
diff --git a/src/crt.c b/src/crt.c
index 8b7f9d5..36011a9 100644
--- a/src/crt.c
+++ b/src/crt.c
@@ -10,6 +10,9 @@ static char rcsid[] = "$Id$";
 
 /*
  * $Log$
+ * Revision 1.3  2008/02/04 20:23:55  james
+ * *** empty log message ***
+ *
  * Revision 1.2  2008/02/04 02:05:06  james
  * *** empty log message ***
  *
@@ -21,15 +24,94 @@ static char rcsid[] = "$Id$";
 #include "project.h"
 
 void
+crt_erase (CRT * c, CRT_Pos s, CRT_Pos e,int ea)
+{
+  CRT_CA *ps = &c->screen[CRT_ADDR_POS (&s)];
+  CRT_CA *pe = &c->screen[CRT_ADDR_POS (&e)];
+
+  while (ps <= pe)
+    {
+      ps->chr = ' ';
+      if (ea)
+      ps->attr = CRT_ATTR_NORMAL;
+      ps++;
+    }
+
+}
+
+void
 crt_cls (CRT * c)
 {
+  CRT_Pos s = { 0, 0 };
+  CRT_Pos e = { CRT_COLS - 1, CRT_ROWS - 1 };
   int i;
 
-  for (i = 0; i < CRT_CELS; ++i)
+  crt_erase (c, s, e,1);
+
+#if 0
+  for (i = 0; i < CRT_ROWS; ++i)
+    {
+      c->screen[CRT_ADDR (i, i)].chr = '@' + i;
+      c->screen[CRT_ADDR (i, i)].attr = CRT_ATTR_NORMAL;
+    }
+#endif
+
+}
+
+void
+crt_scroll_up (CRT * c, CRT_Pos s, CRT_Pos e,int ea)
+{
+  int l, n;
+  int p;
+
+  s.x=0;
+  e.x=CRT_COLS-1;
+
+  l = e.x - s.x;
+  l++;
+  l *= sizeof (CRT_CA);
+
+  n = e.y - s.y;
+
+  p = CRT_ADDR_POS (&s);
+
+  while (n--)
     {
-      c->screen[i].chr = ' ';
-      c->screen[i].chr = CRT_ATTR_NORMAL;
+      memcpy (&c->screen[p], &c->screen[p + CRT_COLS], l);
+      p += CRT_COLS;
     }
+
+  s.y = e.y;
+  crt_erase (c, s, e,ea);
+
+}
+
+void
+crt_scroll_down (CRT * c, CRT_Pos s, CRT_Pos e,int ea)
+{
+  int l, n;
+  int p;
+
+  s.x=0;
+  e.x=CRT_COLS-1;
+
+  l = e.x - s.x;
+  l++;
+  l *= sizeof (CRT_CA);
+
+  n = e.y - s.y;
+
+  p = CRT_ADDR_POS (&e);
+
+  while (n--)
+    {
+      memcpy (&c->screen[p], &c->screen[p + CRT_COLS], l);
+      p -= CRT_COLS;
+    }
+
+  e.y = s.y;
+  crt_erase (c, s, e,ea);
+
 }
 
 void