arch/i386-all/exec/preparecontext.c

   1 /*
   2     Copyright © 1995-2017, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: PrepareContext() - Prepare a task context for dispatch, i386 version
   6     Lang: english
   7 */
   8
   9 #include <exec/types.h>
  10 #include <exec/execbase.h>
  11 #include <exec/memory.h>
  12 #include <utility/tagitem.h>
  13 #include <proto/alib.h>
  14 #include <aros/i386/cpucontext.h>
  15
  16 #include "exec_intern.h"
  17 #include "exec_util.h"
  18 #if defined(__AROSEXEC_SMP__)
  19 #include "etask.h"
  20 #endif
  21
  22 #define _PUSH(sp, val) *--sp = (IPTR)val
  23
  24 BOOL PrepareContext(struct Task *task, APTR entryPoint, APTR fallBack,
  25                     const struct TagItem *tagList, struct ExecBase *SysBase)
  26 {
  27     IPTR args[8] = {0};
  28     WORD numargs = 0;
  29     IPTR *sp = task->tc_SPReg;
  30     struct TagItem *t;
  31     struct ExceptionContext *ctx;
  32
  33     if (!(task->tc_Flags & TF_ETASK) )
  34         return FALSE;
  35
  36     ctx = KrnCreateContext();
  37     task->tc_UnionETask.tc_ETask->et_RegFrame = ctx;
  38     if (!ctx)
  39         return FALSE;
  40
  41     while((t = LibNextTagItem((struct TagItem **)&tagList)))
  42     {
  43         switch(t->ti_Tag)
  44         {
  45 #if defined(__AROSEXEC_SMP__)
  46             case TASKTAG_AFFINITY:
  47                 IntETask(task->tc_UnionETask.tc_ETask)->iet_CpuAffinity = t->ti_Data;
  48                 break;
  49 #endif
  50
  51 #define HANDLEARG(x)                      \
  52         case TASKTAG_ARG ## x:            \
  53             args[x - 1] = t->ti_Data;     \
  54             if (x > numargs) numargs = x; \
  55             break;
  56
  57         HANDLEARG(1)
  58         HANDLEARG(2)
  59         HANDLEARG(3)
  60         HANDLEARG(4)
  61         HANDLEARG(5)
  62         HANDLEARG(6)
  63         HANDLEARG(7)
  64         HANDLEARG(8)
  65         }
  66     }
  67
  68     /*
  69         There is not much to do here, or at least that is how it
  70         appears. Most of the work is done in the kernel_cpu.h macros.
  71     */
  72
  73     if (numargs)
  74     {
  75         /* On i386 C function gets all param on stack */
  76         while(numargs--)
  77         {
  78             _PUSH(sp, args[numargs]);
  79         }
  80     }
  81
  82     /* First we push the return address */
  83     _PUSH(sp, fallBack);
  84
  85     /* Then set up the frame to be used by Dispatch() */
  86     ctx->ebp = 0;
  87     ctx->eip = (IPTR)entryPoint;
  88     ctx->esp = (IPTR)sp;
  89
  90     /* We return the new stack pointer back to the caller. */
  91     task->tc_SPReg = sp;
  92
  93     return TRUE;
  94 } /* PrepareContext() */