bsd/netinet/in_stat.c

   1 /*
   2  * Copyright (c) 2017 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <netinet/in_stat.h>
  30
  31 #define IN_STAT_ACTIVITY_GRANULARITY            8       /* 8 sec granularity */
  32 #define IN_STAT_ACTIVITY_TIME_SEC_SHIFT         3       /* 8 sec per bit */
  33 #define IN_STAT_ACTIVITY_BITMAP_TOTAL_SIZE      ((uint64_t) 128)
  34 #define IN_STAT_ACTIVITY_BITMAP_FIELD_SIZE      ((uint64_t) 64)
  35 #define IN_STAT_ACTIVITY_TOTAL_TIME             ((uint64_t) (8 * 128))
  36 #define IN_STAT_SET_MOST_SIGNIFICANT_BIT        ((u_int64_t )0x8000000000000000)
  37
  38 void
  39 in_stat_set_activity_bitmap(activity_bitmap_t *activity, uint64_t now)
  40 {
  41         uint64_t elapsed_time, slot;
  42         uint64_t *bitmap;
  43         if (activity->start == 0) {
  44                 activity->start = now;
  45         }
  46         elapsed_time = now - activity->start;
  47
  48         slot = elapsed_time >> IN_STAT_ACTIVITY_TIME_SEC_SHIFT;
  49         if (slot < IN_STAT_ACTIVITY_BITMAP_TOTAL_SIZE) {
  50                 if (slot < IN_STAT_ACTIVITY_BITMAP_FIELD_SIZE) {
  51                         bitmap = &activity->bitmap[0];
  52                 } else {
  53                         bitmap = &activity->bitmap[1];
  54                         slot -= IN_STAT_ACTIVITY_BITMAP_FIELD_SIZE;
  55                 }
  56                 *bitmap |= (((u_int64_t) 1) << slot);
  57         } else {
  58                 if (slot >= (IN_STAT_ACTIVITY_BITMAP_TOTAL_SIZE * 2)) {
  59                         activity->start = now - IN_STAT_ACTIVITY_TOTAL_TIME;
  60                         activity->bitmap[0] = activity->bitmap[1] = 0;
  61                 } else {
  62                         uint64_t shift =
  63                             slot - (IN_STAT_ACTIVITY_BITMAP_TOTAL_SIZE - 1);
  64                         /*
  65                          * Move the start time and bitmap forward to
  66                          * cover the lost time
  67                          */
  68                         activity->start +=
  69                             (shift << IN_STAT_ACTIVITY_TIME_SEC_SHIFT);
  70                         if (shift > IN_STAT_ACTIVITY_BITMAP_FIELD_SIZE) {
  71                                 activity->bitmap[0] = activity->bitmap[1];
  72                                 activity->bitmap[1] = 0;
  73                                 shift -= IN_STAT_ACTIVITY_BITMAP_FIELD_SIZE;
  74                                 if (shift == IN_STAT_ACTIVITY_BITMAP_FIELD_SIZE) {
  75                                         activity->bitmap[0] = 0;
  76                                 } else {
  77                                         activity->bitmap[0] >>= shift;
  78                                 }
  79                         } else {
  80                                 uint64_t mask_lower, tmp;
  81                                 uint64_t b1_low, b0_high;
  82
  83                                 /*
  84                                  * generate a mask with all of lower
  85                                  * 'shift' bits set
  86                                  */
  87                                 tmp = (((uint64_t)1) << (shift - 1));
  88                                 mask_lower = ((tmp - 1) ^ tmp);
  89                                 activity->bitmap[0] >>= shift;
  90                                 b1_low = (activity->bitmap[1] & mask_lower);
  91
  92                                 b0_high = (b1_low <<
  93                                     (IN_STAT_ACTIVITY_BITMAP_FIELD_SIZE -
  94                                     shift));
  95                                 activity->bitmap[0] |= b0_high;
  96                                 activity->bitmap[1] >>= shift;
  97                         }
  98                 }
  99                 activity->bitmap[1] |= IN_STAT_SET_MOST_SIGNIFICANT_BIT;
 100         }
 101 }