rom/exec/cause.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Cause() - Cause a software interrupt.
   6     Lang: english
   7 */
   8
   9 #include <exec/execbase.h>
  10 #include <aros/asmcall.h>
  11 #include <hardware/custom.h>
  12
  13 /* Change this to <exec_intern.h> if you move this file... */
  14 #include "exec_intern.h"
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19 #include <exec/interrupts.h>
  20 #include <proto/exec.h>
  21
  22         AROS_LH1(void, Cause,
  23
  24 /*  SYNOPSIS */
  25         AROS_LHA(struct Interrupt *, softint, A1),
  26
  27 /*  LOCATION */
  28         struct ExecBase *, SysBase, 30, Exec)
  29
  30 /*  FUNCTION
  31         Schedule a software interrupt to occur. If the processor is
  32         currently running a user task, then the software interrupt will
  33         prempt the current task and run itself. From a real interrupt, it
  34         will queue the software interrupt for a later time.
  35
  36         Software interrupts are useful from hardware interrupts if you
  37         wish to defer your processing down to a lower level. They can
  38         also be used in some special cases of device I/O. The timer.device
  39         and audio.device allow software interrupt driven timing and
  40         audio output respectively.
  41
  42         Software interrupts are restricted to 5 different priority levels,
  43         +32, +16, 0, -16, -32.
  44
  45         Software interrupts can only be scheduled once.
  46
  47         The software interrupt is called with the following prototype:
  48
  49         AROS_UFH3(void, YourIntCode,
  50             AROS_UFHA(APTR, interruptData, A1),
  51             AROS_UFHA(APTR, interruptCode, A5),
  52             AROS_UFHA(struct ExecBase *, SysBase, A6))
  53
  54         The interruptData is the value of the is_Data field, interruptCode
  55         is the value of the is_Code field - it is included for historical
  56         and compatibility reasons. You can ignore the value of interruptCode,
  57         but you must declare it.
  58
  59     INPUTS
  60         softint     -   The interrupt you wish to schedule. When setting up
  61                         you should set the type of the interrupt to either
  62                         NT_INTERRUPT or NT_UNKNOWN.
  63
  64     RESULT
  65         The software interrupt will be delivered, or queued for later
  66         delivery.
  67
  68     NOTES
  69         No bounds checking on the software interrupt priority is done.
  70         Passing a bad priority to the system can have a strange effect.
  71
  72     EXAMPLE
  73
  74     BUGS
  75         Older versions of the Amiga operating system require that the
  76         software interrupts preserve the A6 register.
  77
  78         Software interrupts which are added from a software interrupt of
  79         lower priority may not be called immediately.
  80
  81     SEE ALSO
  82
  83     INTERNALS
  84
  85 ******************************************************************************/
  86 {
  87     AROS_LIBFUNC_INIT
  88
  89     UBYTE pri;
  90
  91     /* Check to ensure that this node is not already in a list. */
  92     if( softint->is_Node.ln_Type != NT_SOFTINT )
  93     {
  94         /* Scale the priority down to a number between 0 and 4 inclusive
  95            We can use that to index into exec's software interrupt lists. */
  96         pri = ((softint->is_Node.ln_Pri & 0xF0) + 0x20) >> 4;
  97
  98         /* We are accessing an Exec list, protect ourselves. */
  99         Disable();
 100         AddTail((struct List *)&SysBase->SoftInts[pri],
 101                 (struct Node *)softint);
 102         softint->is_Node.ln_Type = NT_SOFTINT;
 103         SysBase->SysFlags |= SFF_SoftInt;
 104         Enable();
 105
 106         /* We now cause a software interrupt. Pretty hard here... */
 107 #ifndef __CXREF__
 108 #error The '$(KERNEL)' interrupt implementation has not been completed.
 109 #endif
 110     }
 111
 112     AROS_LIBFUNC_EXIT
 113 } /* Cause() */
 114
 115 /*
 116     This is the dispatcher for software interrupts. We go through the
 117     lists and remove the interrupts before calling them. Because we
 118     can be interrupted we should not cache the next pointer, but
 119     retreive it from ExecBase each time.
 120
 121     Note: All these arguments are passed to the function, so you must
 122     at least declare all of them. You do not however have to use any
 123     of them (although that is recommended).
 124
 125     This procedure could be more efficient, and it has to be implemented
 126     in the kernel.
 127 */
 128
 129 AROS_UFH5(ULONG, SoftIntDispatch,
 130     AROS_UFHA(ULONG, intReady, D1),
 131     AROS_UFHA(struct Custom *, custom, A0),
 132     AROS_UFHA(IPTR, intData, A1),
 133     AROS_UFHA(ULONG_FUNC, intCode, A5),
 134     AROS_UFHA(struct ExecBase *, SysBase, A6))
 135 {
 136     AROS_USERFUNC_INIT
 137
 138     struct Interrupt *intr;
 139     UBYTE i;
 140     ULONG res;
 141
 142     /*
 143         Hmm, we have to disable software interrupts ONLY. Do NOT disable
 144         any other kind of interrupt. This is very hard to do here however.
 145
 146         The #error line above will trap however.
 147     */
 148
 149     /* Don't bother if there are no software ints queued. */
 150     if( SysBase->SysFlags & SFF_SoftInt )
 151     {
 152         /* Clear Software interrupt pending flag. */
 153         SysBase->SysFlags &= ~(SFF_SoftInt);
 154
 155         for(i=0; i < 4; i++)
 156         {
 157             /* There is a possible problem here with list access */
 158             while( (intr = RemHead((struct List *)&SysBase->SoftInts[i])) )
 159             {
 160                 intr->is_Node.ln_Type = NT_INTERRUPT;
 161
 162                 /* Call the software interrupt. */
 163                 AROS_UFC3(void, intr->is_Code,
 164                     AROS_UFCA(APTR, intr->is_Data, A1),
 165                     AROS_UFCA(ULONG_FUNC, intr->is_Code, A5),
 166                     AROS_UFCA(struct ExecBase *, SysBase, A6));
 167             }
 168         }
 169     }
 170
 171     /* We now re-enable software interrupts. But we can't do it here. */
 172     AROS_USERFUNC_EXIT
 173 }
 174