workbench/c/ChangeTaskPri.c

   1 /*
   2     Copyright © 1995-2007, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Change the priority of a task.
   6     Lang: english
   7 */
   8
   9 /**************************************************************************
  10
  11     NAME
  12         ChangeTaskPri
  13
  14     FORMAT
  15         ChangeTaskPri <priority> [ PROCESS <process number> ]
  16
  17     SYNOPSIS
  18         PRI=PRIORITY/A/N,PROCESS/K/N
  19
  20     LOCATION
  21         C:
  22
  23     FUNCTION
  24         The ChangeTaskPri command is used to change the current run
  25         priority of a Task. As AROS is a multitasking operating
  26         system, you can determine which tasks receive more CPU time
  27         by changing their priorities.
  28
  29         The value of |priority| can be from -128 to 127, however values
  30         greater than 4 are not recommended as they can interfere with
  31         vital system processes. Higher values will give tasks a higher
  32         CPU priority.
  33
  34         You can use the Status command to examine the list of Tasks that
  35         are running and their process numbers.
  36
  37     EXAMPLE
  38
  39         1.SYS:> ChangeTaskPri 1 Process 1
  40
  41             Set the priority of the current process to 1.
  42
  43         1.SYS:> ChangeTaskPri 1
  44
  45             Also sets the priority of the current process to 1.
  46
  47     SEE ALSO
  48         Status
  49
  50 **************************************************************************/
  51
  52 #include <exec/types.h>
  53 #include <exec/tasks.h>
  54 #include <dos/dosextens.h>
  55 #include <dos/rdargs.h>
  56 #include <proto/exec.h>
  57 #include <proto/dos.h>
  58 #include <utility/tagitem.h>
  59
  60 #define ARG_TEMPLATE    "PRI=PRIORITY/A/N,PROCESS/N"
  61 #define ARG_PRI         0
  62 #define ARG_PROCESS     1
  63 #define TOTAL_ARGS      2
  64
  65 const TEXT version[] = "$VER: ChangeTaskPri 41.2 (13.9.2005)";
  66 static const char exthelp[] =
  67     "ChangeTaskPri : Change the priority of a CLI task\n"
  68     "\tPRI=PRIORITY/A/N      New priority of task\n"
  69     "\tPROCESS/K             Optional process number of change\n";
  70
  71 int __nocommandline = 1;
  72
  73 int main(void)
  74 {
  75     struct Process *pr = NULL;
  76     struct RDArgs *rda = NULL, *rdargs;
  77     IPTR args[TOTAL_ARGS] = { 0, 0 };
  78     int error = 0;
  79
  80     rda = AllocDosObject(DOS_RDARGS, NULL);
  81     if( rda != NULL )
  82     {
  83         rda->RDA_ExtHelp = (STRPTR)exthelp;
  84
  85         rdargs = ReadArgs(ARG_TEMPLATE, (IPTR *)args, rda);
  86         if( rdargs != NULL )
  87         {
  88             Forbid();
  89             if( args[ARG_PROCESS] != 0 ) {
  90 //              Printf("PROCESS = %ld\n", *(LONG *)args[ARG_PROCESS]);
  91                 pr = FindCliProc(*(LONG *)args[ARG_PROCESS]);
  92             }
  93             else
  94                 pr = (struct Process *)FindTask(NULL);
  95 //          Printf("pr = 0x%08lx\n", pr);
  96             if( pr != NULL )
  97             {
  98                 LONG pri = (LONG)(*(IPTR *)args[ARG_PRI]);
  99
 100                 /* Check the bounds on the priority */
 101                 if(pri < -128 || pri > 127 )
 102                     error = ERROR_OBJECT_TOO_LARGE;
 103                 else
 104                     /* Set the priority */
 105                     SetTaskPri( (struct Task *)pr, pri);
 106                 Permit();
 107             }
 108             else
 109             {
 110                 BPTR errStream;
 111                 Permit();
 112                 errStream = Output();
 113
 114                 pr = (struct Process *)FindTask(NULL);
 115                 if( pr->pr_CES != BNULL )
 116                     errStream = pr->pr_CES;
 117
 118                 FPuts(errStream, "ChangeTaskPri: Process does not exist.\n");
 119                 SetIoErr(0);
 120                 error = -1;
 121             }
 122             FreeArgs(rdargs);
 123         } /* ReadArgs() ok */
 124         else
 125             error = IoErr();
 126         FreeDosObject(DOS_RDARGS, rda);
 127     } /* Got a RDArgs * */
 128     else
 129         error = IoErr();
 130     if( error != -1 && error != 0 )
 131     {
 132         PrintFault(error, "ChangeTaskPri");
 133         return RETURN_FAIL;
 134     }
 135     SetIoErr(0);
 136     return 0;
 137 }