WIP minor improvements to conio/screen for scrolling, still doesn't work reliably once we print more than 25 lines

src/conio.c

@@ -35,7 +35,7 @@ void _cputs(char *ptr)
   while ((char)*ptr != 0x0) { 
     _putch((char)*ptr);
     if (*ptr == '\n') {
-      _cursor_y += 1;
+      if ( _cursor_y < 24 ) _cursor_y += 1;
       _cursor_x = 0;
       setCursorPosition(_cursor_x, _cursor_y);
     } else {

src/screen.c

@@ -17,6 +17,32 @@ void blankScreen(void)
   }
 }
 
+void scrollScreenUp(char start, char lines)
+{  
+#ifndef __GNUC__
+#asm
+  push bx;
+  mov bx, sp;
+  push ax;
+  push cx;
+  push dx;
+  mov ch, [bx+4];
+  mov cl, #0x00;
+  mov dh, #0x18;
+  mov dl, #0x4F;
+  mov al, [bx+6];
+  mov ah, #0x06;
+  mov bx, #0x0;
+  int 0x10;
+  pop dx;
+  pop cx;
+  pop ax;
+  pop bx;
+#endasm
+  return;
+#endif
+}
+
 void setCursorPosition(char x, char y)
 {
 #ifndef __GNUC__

src/screen.h

@@ -8,5 +8,6 @@ void setCursorPosition(char x, char y);
 void backupCursor();
 void advanceCursor();
 void blankScreen();
+void scrollScreenUp(char start, char lines);
 
 #endif /* _SCREEN_H_ */