rom/graphics/ownblitter.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Try to own the blitter for private usage
   6     Lang: english
   7 */
   8
   9 #define DEBUG 0
  10 #include <aros/debug.h>
  11
  12 #include <proto/exec.h>
  13 #include <graphics/gfxbase.h>
  14 #include <exec/execbase.h>
  15 #include <exec/tasks.h>
  16
  17 #include "graphics_intern.h"
  18 #include "gfxfuncsupport.h"
  19
  20 /*****************************************************************************
  21
  22     NAME */
  23 #include <proto/graphics.h>
  24
  25         AROS_LH0(void, OwnBlitter,
  26
  27 /*  SYNOPSIS */
  28
  29
  30 /*  LOCATION */
  31         struct GfxBase *, GfxBase, 76, Graphics)
  32
  33 /*  FUNCTION
  34         The blitter is allocated for exclusive use by the calling task.
  35         This function returns immediately if no other task is using
  36         the blitter right now or if no blits are in the queues (QBlit(),
  37         QBSBlit()). Otherwise the function will block until the blitter
  38         can be accessed.
  39         It is good practice to start the blitter immediately after calling
  40         this function and then call DisownBlitter() so other tasks can
  41         use the blitter.
  42
  43     INPUTS
  44
  45     RESULT
  46
  47     NOTES
  48
  49     EXAMPLE
  50
  51     BUGS
  52
  53     SEE ALSO
  54         DisownBlitter()
  55
  56     INTERNALS
  57
  58     HISTORY
  59
  60 ******************************************************************************/
  61 {
  62   AROS_LIBFUNC_INIT
  63
  64   struct BlitWaitQNode node;
  65   struct Task *me;
  66
  67   me = FindTask(NULL);
  68
  69   D(bug("OwnBlitter: Request by Task %p)\n", me));
  70
  71   Disable();
  72   for (;;) {
  73     if (GfxBase->BlitOwner == NULL) {
  74       GfxBase->BlitOwner = me;
  75       Enable();
  76       D(bug("OwnBlitter: Now owned by Task %p\n", me));
  77       return;
  78     }
  79     node.task = me;
  80     AddTail(&GfxBase->BlitWaitQ, (struct Node*)&node);
  81     SetSignal(0, 1 << SIGB_BLIT);
  82     Wait(1 << SIGB_BLIT);
  83     Remove((struct Node*)&node);
  84   }
  85
  86   AROS_LIBFUNC_EXIT
  87 } /* OwnBlitter */