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     InitETask(task);
 126     if (!task->tc_UnionETask.tc_ETask)
 127         return NULL;
 128
 129     /* Get new stackpointer. */
 130     if (task->tc_SPReg==NULL)
 131         task->tc_SPReg = (UBYTE *)(task->tc_SPUpper) - SP_OFFSET;
 132
 133 #ifdef AROS_STACKALIGN
 134     if ((IPTR)task->tc_SPReg & (AROS_STACKALIGN - 1))
 135     {
 136         DADDTASK("NewAddTask with unaligned stack pointer (0x%p)! Fixing...", task->tc_SPReg);
 137         task->tc_SPReg = (APTR)((IPTR)task->tc_SPReg & ~(AROS_STACKALIGN - 1));
 138     }
 139 #endif
 140     DADDTASK("NewAddTask: SPLower: 0x%p SPUpper: 0x%p SP: 0x%p", task->tc_SPLower, task->tc_SPUpper, task->tc_SPReg);
 141
 142     if (task->tc_Flags & TF_STACKCHK)
 143     {
 144         UBYTE *startfill, *endfill;
 145
 146         startfill = (UBYTE *)task->tc_SPLower;
 147         endfill   = ((UBYTE *)task->tc_SPReg) - 16;
 148
 149         while(startfill <= endfill)
 150         {
 151             *startfill++ = 0xE1;
 152         }
 153     }
 154
 155     /* Default finalizer? */
 156     if(finalPC==NULL)
 157         finalPC=SysBase->TaskExitCode;
 158
 159     /* Init new context. */
 160     if (!PrepareContext(task, initialPC, finalPC, tagList, SysBase))
 161     {
 162         CleanupETask(task);
 163         return NULL;
 164     }
 165
 166     /* Set the task flags for switch and launch. */
 167     if(task->tc_Switch)
 168         task->tc_Flags|=TF_SWITCH;
 169
 170     if(task->tc_Launch)
 171         task->tc_Flags|=TF_LAUNCH;
 172
 173     /*
 174         Protect the task lists. This must be done with Disable() because
 175         of Signal() which is usable from interrupts and may change those
 176         lists.
 177      */
 178     Disable();
 179
 180     /* Add the new task to the ready list. */
 181     task->tc_State=TS_READY;
 182     Enqueue(&SysBase->TaskReady,&task->tc_Node);
 183
 184     /*
 185         Determine if a task switch is necessary. (If the new task has a
 186         higher priority than the current one and the current one
 187         is still active.) If the current task isn't of type TS_RUN it
 188         is already gone.
 189     */
 190
 191     if (task->tc_Node.ln_Pri > SysBase->ThisTask->tc_Node.ln_Pri &&
 192        SysBase->ThisTask->tc_State == TS_RUN)
 193     {
 194         D(bug("[AddTask] Rescheduling...\n"));
 195
 196         /* Reschedule() will take care about disabled task switching automatically */
 197         Reschedule();
 198     }
 199
 200     Enable();
 201
 202     DADDTASK("Added task 0x%p", task);
 203     return task;
 204
 205     AROS_LIBFUNC_EXIT
 206 } /* NewAddTask */