rom/exec/newaddtask.c

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Add a task.
   6     Lang: english
   7 */
   8
   9 #include <exec/execbase.h>
  10 #include <exec/memory.h>
  11 #include <utility/tagitem.h>
  12 #include <aros/debug.h>
  13 #include <aros/libcall.h>
  14 #include <proto/exec.h>
  15
  16 #include "etask.h"
  17 #include "exec_util.h"
  18 #include "exec_debug.h"
  19 #include "taskstorage.h"
  20
  21 /*****************************************************************************
  22
  23     NAME */
  24
  25         AROS_LH4(APTR, NewAddTask,
  26
  27 /*  SYNOPSIS */
  28         AROS_LHA(struct Task *,     task,      A1),
  29         AROS_LHA(APTR,              initialPC, A2),
  30         AROS_LHA(APTR,              finalPC,   A3),
  31         AROS_LHA(struct TagItem *,  tagList,   A4),
  32
  33 /*  LOCATION */
  34         struct ExecBase *, SysBase, 176, Exec)
  35
  36 /*  FUNCTION
  37         Add a new task to the system. If the new task has the highest
  38         priority of all and task switches are allowed it will be started
  39         immediately.
  40         Certain task fields should be intitialized and a stack must be
  41         allocated before calling this function. tc_SPReg will be used as the
  42         starting location for the stack pointer, i.e. a part of the stack can
  43         be reserved to pass the task some initial arguments.
  44         Memory can be added to the tc_MemEntry list and will be freed when the
  45         task dies. The new task's registers are set to 0.
  46
  47     INPUTS
  48         task      - Pointer to task structure.
  49         initialPC - Entry point for the new task.
  50         finalPC   - Routine that is called if the initialPC() function returns.
  51                     A NULL pointer installs the default finalizer.
  52
  53     RESULT
  54         The address of the new task or NULL if the operation failed (can only
  55         happen with TF_ETASK set - currenty not implemented).
  56
  57     NOTES
  58         This function is private. Use MorphOS-compatible NewCreateTaskA()
  59         in your applications.
  60
  61     EXAMPLE
  62
  63     BUGS
  64
  65     SEE ALSO
  66         RemTask()
  67
  68     INTERNALS
  69
  70     HISTORY
  71
  72 ******************************************************************************/
  73 {
  74     AROS_LIBFUNC_INIT
  75
  76     ASSERT_VALID_PTR(task);
  77
  78     /* Sigh - you should provide a name for your task. */
  79     if(task->tc_Node.ln_Name==NULL)
  80         task->tc_Node.ln_Name="unknown task";
  81
  82     DADDTASK("NewAddTask (0x%p (\"%s\"), 0x%p, 0x%p)", task, task->tc_Node.ln_Name, initialPC, finalPC);
  83
  84     /* Initialize the memory entry list if the caller forgot */
  85     if (!task->tc_MemEntry.lh_Head)
  86         NEWLIST(&task->tc_MemEntry);
  87
  88     DADDTASK("NewAddTask MemEntry head: 0x%p", GetHead(&task->tc_MemEntry.lh_Head));
  89
  90     /* Set node type to NT_TASK if not set to something else. */
  91     if(!task->tc_Node.ln_Type)
  92         task->tc_Node.ln_Type=NT_TASK;
  93
  94     /* This is moved into SysBase at the tasks's startup */
  95     task->tc_IDNestCnt=-1;
  96     task->tc_TDNestCnt=-1;
  97
  98     task->tc_State = TS_ADDED;
  99     task->tc_Flags = 0;
 100
 101     task->tc_SigWait = 0;
 102     task->tc_SigRecvd = 0;
 103     task->tc_SigExcept = 0;
 104
 105     /* Signals default to all system signals allocated. */
 106     if(task->tc_SigAlloc==0)
 107         task->tc_SigAlloc=SysBase->TaskSigAlloc;
 108
 109     /* Currently only used for segmentation violation */
 110     if(task->tc_TrapCode==NULL)
 111         task->tc_TrapCode=SysBase->TaskTrapCode;
 112
 113     if(task->tc_ExceptCode==NULL)
 114         task->tc_ExceptCode=SysBase->TaskExceptCode;
 115
 116     /*
 117      * EXECF_StackSnoop can be set or reset at runtime.
 118      * However task's stack is either snooped or not, it's problematic
 119      * to turn it on at runtime. So we initialize it when the task starts up.
 120      */
 121     if (PrivExecBase(SysBase)->IntFlags & EXECF_StackSnoop)
 122         task->tc_Flags |= TF_STACKCHK;
 123
 124     /* Initialize ETask */
 125     if (!InitETask(task))
 126         return NULL;
 127
 128     /* Get new stackpointer. */
 129     if (task->tc_SPReg==NULL)
 130         task->tc_SPReg = (UBYTE *)(task->tc_SPUpper) - SP_OFFSET;
 131
 132 #ifdef AROS_STACKALIGN
 133     if ((IPTR)task->tc_SPReg & (AROS_STACKALIGN - 1))
 134     {
 135         DADDTASK("NewAddTask with unaligned stack pointer (0x%p)! Fixing...", task->tc_SPReg);
 136         task->tc_SPReg = (APTR)((IPTR)task->tc_SPReg & ~(AROS_STACKALIGN - 1));
 137     }
 138 #endif
 139     DADDTASK("NewAddTask: SPLower: 0x%p SPUpper: 0x%p SP: 0x%p", task->tc_SPLower, task->tc_SPUpper, task->tc_SPReg);
 140
 141     if (task->tc_Flags & TF_STACKCHK)
 142     {
 143         UBYTE *startfill, *endfill;
 144
 145         startfill = (UBYTE *)task->tc_SPLower;
 146         endfill   = ((UBYTE *)task->tc_SPReg) - 16;
 147
 148         while(startfill <= endfill)
 149         {
 150             *startfill++ = 0xE1;
 151         }
 152     }
 153
 154     /* Default finalizer? */
 155     if(finalPC==NULL)
 156         finalPC=SysBase->TaskExitCode;
 157
 158     /* Init new context. */
 159     if (!PrepareContext(task, initialPC, finalPC, tagList, SysBase))
 160     {
 161         CleanupETask(task);
 162         return NULL;
 163     }
 164
 165     /* Set the task flags for switch and launch. */
 166     if(task->tc_Switch)
 167         task->tc_Flags|=TF_SWITCH;
 168
 169     if(task->tc_Launch)
 170         task->tc_Flags|=TF_LAUNCH;
 171
 172     /*
 173         Protect the task lists. This must be done with Disable() because
 174         of Signal() which is usable from interrupts and may change those
 175         lists.
 176      */
 177     Disable();
 178
 179     /* Add the new task to the ready list. */
 180     task->tc_State=TS_READY;
 181     Enqueue(&SysBase->TaskReady,&task->tc_Node);
 182
 183     /*
 184         Determine if a task switch is necessary. (If the new task has a
 185         higher priority than the current one and the current one
 186         is still active.) If the current task isn't of type TS_RUN it
 187         is already gone.
 188     */
 189
 190     if (task->tc_Node.ln_Pri > SysBase->ThisTask->tc_Node.ln_Pri &&
 191        SysBase->ThisTask->tc_State == TS_RUN)
 192     {
 193         D(bug("[AddTask] Rescheduling...\n"));
 194
 195         /* Reschedule() will take care about disabled task switching automatically */
 196         Reschedule();
 197     }
 198
 199     Enable();
 200
 201     DADDTASK("Added task 0x%p", task);
 202     return task;
 203
 204     AROS_LIBFUNC_EXIT
 205 } /* NewAddTask */