arch/arm-all/exec/preparecontext.c

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: PrepareContext() - Prepare a task context for dispatch, ARM version.
   6     Lang: english
   7 */
   8
   9 #include <exec/execbase.h>
  10 #include <exec/memory.h>
  11 #include <utility/tagitem.h>
  12 #include <proto/arossupport.h>
  13 #include <proto/kernel.h>
  14 #include <aros/arm/cpucontext.h>
  15
  16 #include "exec_intern.h"
  17 #include "exec_util.h"
  18
  19 BOOL PrepareContext(struct Task *task, APTR entryPoint, APTR fallBack,
  20                     const struct TagItem *tagList, struct ExecBase *SysBase)
  21 {
  22     struct TagItem *t;
  23     struct ExceptionContext *ctx;
  24     ULONG args[4] = {0};
  25     int numargs = 0;
  26     STACKULONG *sp = task->tc_SPReg;
  27
  28     if (!(task->tc_Flags & TF_ETASK) )
  29         return FALSE;
  30
  31     ctx = KrnCreateContext();
  32     task->tc_UnionETask.tc_ETask->et_RegFrame = ctx;
  33     if (!ctx)
  34         return FALSE;
  35
  36     /* Set up function arguments */
  37     while((t = LibNextTagItem((struct TagItem **)&tagList)))
  38     {
  39         switch(t->ti_Tag)
  40         {
  41 #define REGARG(x)                       \
  42         case TASKTAG_ARG ## x:          \
  43             ctx->r[x - 1] = t->ti_Data; \
  44             break;
  45
  46 #define STACKARG(x)                     \
  47         case TASKTAG_ARG ## x:          \
  48             args[x - 5] = t->ti_Data;   \
  49             if (x - 4 > numargs)        \
  50                 numargs = x - 4;        \
  51             break;
  52
  53         REGARG(1)
  54         REGARG(2)
  55         REGARG(3)
  56         REGARG(4)
  57         STACKARG(5)
  58         STACKARG(6)
  59         STACKARG(7)
  60         STACKARG(8)
  61         }
  62     }
  63
  64     /* Last four arguments are put on stack */
  65     while (numargs > 0)
  66         *--sp = args[--numargs];
  67
  68     task->tc_SPReg = sp;
  69
  70     /* Now prepare return address */
  71     ctx->r[11] = 0;
  72     ctx->lr = (ULONG)fallBack;
  73
  74     ctx->Flags = 0;
  75
  76     /* Then set up the frame to be used by Dispatch() */
  77     ctx->sp = (ULONG)task->tc_SPReg;
  78     ctx->pc = (ULONG)entryPoint;
  79
  80     return TRUE;
  81 } /* PrepareContext() */