[AD] some additions to DGA driver

[Michael Bukin <M.A.Bukin@xxxxxxxxxx>]

This patch includes two features for DGA driver: centering and
clearing video memory.  Centering works with linear DGA modes only and
can be disabled by setting "XDGA_DONT_CENTER_SCREEN" environment
variable.  Video memory is cleared with zeros, but it can be disabled
by setting "XDGA_DONT_CLEAR_MEMORY" env.var.

I don't like using environment variables for disabling these features,
if anyone can find better alternative it should replace environment
variables.


diff -ruN old/allegro-3.9.32/src/x/xwin.c new/allegro-3.9.32/src/x/xwin.c
--- old/allegro-3.9.32/src/x/xwin.c	Mon Mar 13 06:23:53 2000
+++ new/allegro-3.9.32/src/x/xwin.c	Sun Mar 19 17:48:56 2000
@@ -2592,6 +2592,7 @@
    int vid_major_version, vid_minor_version;
    int fb_width, banksize, memsize;
    int s_w, s_h, v_w, v_h;
+   int offset_x, offset_y;
    XF86VidModeModeLine modeline;
    char *fb_addr;
    struct passwd *pass;
@@ -2751,6 +2752,16 @@
       return 0;
    }
 
+   /* Center Allegro screen inside display.  */
+   if ((getenv ("XDGA_DONT_CENTER_SCREEN") == 0) && (banksize >= memsize)) {
+      offset_x = (s_w - w) / 2;
+      offset_y = (s_h - h) / 2;
+   }
+   else {
+      offset_x = 0;
+      offset_y = 0;
+   }
+
    _xwin.screen_width = w;
    _xwin.screen_height = h;
    _xwin.screen_depth = depth;
@@ -2792,6 +2803,16 @@
       return 0;
    }
 
+   /* Clear video memory.  */
+   if (getenv ("XDGA_DONT_CLEAR_MEMORY") == 0) {
+      int offset;
+      for (offset = 0; offset < memsize; offset++) {
+	 if ((offset % banksize) == 0)
+	    XF86DGASetVidPage(_xwin.display, _xwin.screen, offset / banksize);
+	 *(fb_addr + (offset % banksize)) = 0;
+      }
+   }
+
    /* Switch to first bank.  */
    XF86DGASetVidPage(_xwin.display, _xwin.screen, 0);
 
@@ -2799,7 +2820,7 @@
    XF86DGASetViewPort(_xwin.display, _xwin.screen, 0, 0);
 
    /* Create screen bitmap from frame buffer.  */
-   return _xwin_private_create_screen_bitmap(drv, 1, fb_addr, fb_width);
+   return _xwin_private_create_screen_bitmap(drv, 1, fb_addr + offset_y * fb_width + offset_x * (_xwin.fast_visual_depth / 8), fb_width);
 }
 
 BITMAP *_xdga_create_screen(GFX_DRIVER *drv, int w, int h, int vw, int vh, int depth, int fullscr)


-- 
Michael Bukin