rom/graphics/qblit.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Queue a Blit
   6     Lang: english
   7 */
   8
   9 #include <proto/exec.h>
  10 #include <hardware/intbits.h>
  11 #include <hardware/blit.h>
  12 #include <graphics/gfxbase.h>
  13
  14 #include "graphics_intern.h"
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19 #include <proto/graphics.h>
  20
  21         AROS_LH1(void, QBlit,
  22
  23 /*  SYNOPSIS */
  24         AROS_LHA(struct bltnode *, bn, A1),
  25
  26 /*  LOCATION */
  27         struct GfxBase *, GfxBase, 46, Graphics)
  28
  29 /*  FUNCTION
  30         Queues a request for a blit. This request is queued at the end
  31         of the list.
  32
  33     INPUTS
  34         bn - pointer to blitnode structure
  35
  36     RESULT
  37         The routine that function in the bltnode is pointing to is
  38         called when the blitter is ready for work. No other task will
  39         be able to access the blitter while you're doing the blit.
  40         Queued blits have precedence over a task that tries to own the
  41         blitter via OwnBlitter(). So all queued blitter requests will
  42         be done first until the task that attempts a OwnBlitter can
  43         actually access the blitter.
  44
  45     NOTES
  46         Not all hardware has a blitter. On hardware where there is no
  47         blitter, a blitter is simulated. Therefore all code that will
  48         be executed in the function that is called must not contain
  49         code that is hacking the blitter's register but should contain
  50         calls to graphics functions instead.
  51
  52     EXAMPLE
  53
  54     BUGS
  55
  56     SEE ALSO
  57         QBSBlit(), OwnBlitter(), DisownBlitter(), hardware/blit.h
  58
  59     INTERNALS
  60
  61     HISTORY
  62
  63 ******************************************************************************/
  64 {
  65   AROS_LIBFUNC_INIT
  66
  67   /* this function uses the simple FIFO queue blthd (blttl) */
  68
  69   /* I am accessing a public structure and there's no semaphore...
  70    * Interrupts disabled because this is accessed from blitter interrupt.
  71    */
  72   Disable();
  73
  74   if (NULL == GfxBase->blthd)
  75   {
  76     /* OwnBlitter() only if both lists are empty */
  77     if (NULL == GfxBase->bsblthd)
  78       OwnBlitter();
  79
  80     /* it's the first one in the list */
  81     GfxBase->blthd = bn;
  82     GfxBase->blttl = bn;
  83
  84     /* In this case the following also has to happen:
  85        It is my understanding that at the end of every blit an interrupt
  86        occurs that can take care of any blits in this queue or allow
  87        a taks to wake up when it was blocked due to a call to OwnBlitter.
  88        But in this case there might not be such an interrupt for a long
  89        time if no calls to blitterfunctions are made. Therefore this
  90        blit might be queued forever. To avoid this I have to cause
  91        a Blitter interrupt, if no task owns the blitter right now.
  92        (BlitOwner)
  93     */
  94     /*
  95       !!! missing code here!! See explanation above!
  96     */
  97 #if (AROS_FLAVOUR & AROS_FLAVOUR_BINCOMPAT) && defined(mc68000)
  98     {
  99       /* Trigger blitter interrupt */
 100       volatile struct Custom *custom = (struct Custom *)(void **)0xdff000;
 101       custom->intreq = INTF_SETCLR | INTF_BLIT;
 102       custom->intena = INTF_SETCLR | INTF_BLIT;
 103     }
 104 #endif
 105   }
 106   else
 107   {
 108     /* queue it at the end */
 109     GfxBase->blttl->n = bn;
 110     GfxBase->blttl    = bn;
 111   }
 112
 113   Enable();
 114
 115   AROS_LIBFUNC_EXIT
 116 } /* QBlit */