1/*
2 * sched_get_priority_min.c
3 *
4 * Description:
5 * POSIX thread functions that deal with thread scheduling.
6 *
7 * --------------------------------------------------------------------------
8 *
9 *      Pthreads-win32 - POSIX Threads Library for Win32
10 *      Copyright(C) 1998 John E. Bossom
11 *      Copyright(C) 1999,2005 Pthreads-win32 contributors
12 *
13 *      Contact Email: rpj@callisto.canberra.edu.au
14 *
15 *      The current list of contributors is contained
16 *      in the file CONTRIBUTORS included with the source
17 *      code distribution. The list can also be seen at the
18 *      following World Wide Web location:
19 *      http://sources.redhat.com/pthreads-win32/contributors.html
20 *
21 *      This library is free software; you can redistribute it and/or
22 *      modify it under the terms of the GNU Lesser General Public
23 *      License as published by the Free Software Foundation; either
24 *      version 2 of the License, or (at your option) any later version.
25 *
26 *      This library is distributed in the hope that it will be useful,
27 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
28 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
29 *      Lesser General Public License for more details.
30 *
31 *      You should have received a copy of the GNU Lesser General Public
32 *      License along with this library in the file COPYING.LIB;
33 *      if not, write to the Free Software Foundation, Inc.,
34 *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
35 */
36
37#include "pthread.h"
38#include "implement.h"
39#include "sched.h"
40
41/*
42 * On Windows98, THREAD_PRIORITY_LOWEST is (-2) and
43 * THREAD_PRIORITY_HIGHEST is 2, and everything works just fine.
44 *
45 * On WinCE 3.0, it so happen that THREAD_PRIORITY_LOWEST is 5
46 * and THREAD_PRIORITY_HIGHEST is 1 (yes, I know, it is funny:
47 * highest priority use smaller numbers) and the following happens:
48 *
49 * sched_get_priority_min() returns 5
50 * sched_get_priority_max() returns 1
51 *
52 * The following table shows the base priority levels for combinations
53 * of priority class and priority value in Win32.
54 *
55 *   Process Priority Class               Thread Priority Level
56 *   -----------------------------------------------------------------
57 *   1 IDLE_PRIORITY_CLASS                THREAD_PRIORITY_IDLE
58 *   1 BELOW_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_IDLE
59 *   1 NORMAL_PRIORITY_CLASS              THREAD_PRIORITY_IDLE
60 *   1 ABOVE_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_IDLE
61 *   1 HIGH_PRIORITY_CLASS                THREAD_PRIORITY_IDLE
62 *   2 IDLE_PRIORITY_CLASS                THREAD_PRIORITY_LOWEST
63 *   3 IDLE_PRIORITY_CLASS                THREAD_PRIORITY_BELOW_NORMAL
64 *   4 IDLE_PRIORITY_CLASS                THREAD_PRIORITY_NORMAL
65 *   4 BELOW_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_LOWEST
66 *   5 IDLE_PRIORITY_CLASS                THREAD_PRIORITY_ABOVE_NORMAL
67 *   5 BELOW_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_BELOW_NORMAL
68 *   5 Background NORMAL_PRIORITY_CLASS   THREAD_PRIORITY_LOWEST
69 *   6 IDLE_PRIORITY_CLASS                THREAD_PRIORITY_HIGHEST
70 *   6 BELOW_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_NORMAL
71 *   6 Background NORMAL_PRIORITY_CLASS   THREAD_PRIORITY_BELOW_NORMAL
72 *   7 BELOW_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_ABOVE_NORMAL
73 *   7 Background NORMAL_PRIORITY_CLASS   THREAD_PRIORITY_NORMAL
74 *   7 Foreground NORMAL_PRIORITY_CLASS   THREAD_PRIORITY_LOWEST
75 *   8 BELOW_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_HIGHEST
76 *   8 NORMAL_PRIORITY_CLASS              THREAD_PRIORITY_ABOVE_NORMAL
77 *   8 Foreground NORMAL_PRIORITY_CLASS   THREAD_PRIORITY_BELOW_NORMAL
78 *   8 ABOVE_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_LOWEST
79 *   9 NORMAL_PRIORITY_CLASS              THREAD_PRIORITY_HIGHEST
80 *   9 Foreground NORMAL_PRIORITY_CLASS   THREAD_PRIORITY_NORMAL
81 *   9 ABOVE_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_BELOW_NORMAL
82 *  10 Foreground NORMAL_PRIORITY_CLASS   THREAD_PRIORITY_ABOVE_NORMAL
83 *  10 ABOVE_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_NORMAL
84 *  11 Foreground NORMAL_PRIORITY_CLASS   THREAD_PRIORITY_HIGHEST
85 *  11 ABOVE_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_ABOVE_NORMAL
86 *  11 HIGH_PRIORITY_CLASS                THREAD_PRIORITY_LOWEST
87 *  12 ABOVE_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_HIGHEST
88 *  12 HIGH_PRIORITY_CLASS                THREAD_PRIORITY_BELOW_NORMAL
89 *  13 HIGH_PRIORITY_CLASS                THREAD_PRIORITY_NORMAL
90 *  14 HIGH_PRIORITY_CLASS                THREAD_PRIORITY_ABOVE_NORMAL
91 *  15 HIGH_PRIORITY_CLASS                THREAD_PRIORITY_HIGHEST
92 *  15 HIGH_PRIORITY_CLASS                THREAD_PRIORITY_TIME_CRITICAL
93 *  15 IDLE_PRIORITY_CLASS                THREAD_PRIORITY_TIME_CRITICAL
94 *  15 BELOW_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_TIME_CRITICAL
95 *  15 NORMAL_PRIORITY_CLASS              THREAD_PRIORITY_TIME_CRITICAL
96 *  15 ABOVE_NORMAL_PRIORITY_CLASS        THREAD_PRIORITY_TIME_CRITICAL
97 *  16 REALTIME_PRIORITY_CLASS            THREAD_PRIORITY_IDLE
98 *  17 REALTIME_PRIORITY_CLASS            -7
99 *  18 REALTIME_PRIORITY_CLASS            -6
100 *  19 REALTIME_PRIORITY_CLASS            -5
101 *  20 REALTIME_PRIORITY_CLASS            -4
102 *  21 REALTIME_PRIORITY_CLASS            -3
103 *  22 REALTIME_PRIORITY_CLASS            THREAD_PRIORITY_LOWEST
104 *  23 REALTIME_PRIORITY_CLASS            THREAD_PRIORITY_BELOW_NORMAL
105 *  24 REALTIME_PRIORITY_CLASS            THREAD_PRIORITY_NORMAL
106 *  25 REALTIME_PRIORITY_CLASS            THREAD_PRIORITY_ABOVE_NORMAL
107 *  26 REALTIME_PRIORITY_CLASS            THREAD_PRIORITY_HIGHEST
108 *  27 REALTIME_PRIORITY_CLASS             3
109 *  28 REALTIME_PRIORITY_CLASS             4
110 *  29 REALTIME_PRIORITY_CLASS             5
111 *  30 REALTIME_PRIORITY_CLASS             6
112 *  31 REALTIME_PRIORITY_CLASS            THREAD_PRIORITY_TIME_CRITICAL
113 *
114 * Windows NT:  Values -7, -6, -5, -4, -3, 3, 4, 5, and 6 are not supported.
115 *
116 */
117
118
119int
120sched_get_priority_min (int policy)
121{
122  if (policy < SCHED_MIN || policy > SCHED_MAX)
123    {
124      errno = EINVAL;
125      return -1;
126    }
127
128#if (THREAD_PRIORITY_LOWEST > THREAD_PRIORITY_NORMAL)
129  /* WinCE? */
130  return PTW32_MIN (THREAD_PRIORITY_IDLE, THREAD_PRIORITY_TIME_CRITICAL);
131#else
132  /* This is independent of scheduling policy in Win32. */
133  return PTW32_MIN (THREAD_PRIORITY_IDLE, THREAD_PRIORITY_TIME_CRITICAL);
134#endif
135}
136