workbench/libs/lowlevel/addvblankint.c

   1 /*
   2     Copyright © 1995-2007, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: English
   7 */
   8
   9 #include "lowlevel_intern.h"
  10
  11 #include <aros/libcall.h>
  12 #include <exec/types.h>
  13 #include <libraries/lowlevel.h>
  14 #include <hardware/intbits.h>
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19
  20       AROS_LH2(APTR, AddVBlankInt,
  21
  22 /*  SYNOPSIS */
  23       AROS_LHA(APTR, intRoutine, A0),
  24       AROS_LHA(APTR, intData, A1),
  25
  26 /*  LOCATION */
  27       struct LowLevelBase *, LowLevelBase, 18, LowLevel)
  28
  29 /*  FUNCTION
  30
  31     Add a callback function that should be executed every vertical blank.
  32     If your program can exit without rebooting the machine, RemVBlankInt()
  33     has to be called prior to exiting.
  34         Only one interrupt routine may be added; always check the return
  35     value of this function in case some other program already has used this
  36     function.
  37
  38     INPUTS
  39
  40     intRoutine  --  the callback function to invoke each vertical blank
  41     intData     --  data passed to the callback function
  42
  43     RESULT
  44
  45     A handle used to manipulate the interrupt or NULL if the call failed.
  46
  47     BUGS
  48
  49     SEE ALSO
  50
  51     RemVBlankInt()
  52
  53     INTERNALS
  54
  55 *****************************************************************************/
  56 {
  57     AROS_LIBFUNC_INIT
  58
  59     APTR result;
  60
  61     if (intRoutine == NULL)
  62     {
  63         return NULL;
  64     }
  65
  66     ObtainSemaphore(&LowLevelBase->ll_Lock);
  67
  68     if (LowLevelBase->ll_VBlank.is_Code == NULL)
  69     {
  70         LowLevelBase->ll_VBlank.is_Code = intRoutine;
  71         LowLevelBase->ll_VBlank.is_Data = intData;
  72
  73         AddIntServer(INTB_VERTB, &LowLevelBase->ll_VBlank);
  74         result = (APTR)&LowLevelBase->ll_VBlank;
  75     }
  76     else
  77     {
  78         result = NULL;
  79     }
  80
  81     ReleaseSemaphore(&LowLevelBase->ll_Lock);
  82
  83     return result;
  84
  85     AROS_LIBFUNC_EXIT
  86 } /* AddVBlankInt */