kernel/range.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Range add and subtract
   4  */
   5 #include <linux/init.h>
   6 #include <linux/minmax.h>
   7 #include <linux/printk.h>
   8 #include <linux/sort.h>
   9 #include <linux/string.h>
  10 #include <linux/range.h>
  11
  12 int add_range(struct range *range, int az, int nr_range, u64 start, u64 end)
  13 {
  14         if (start >= end)
  15                 return nr_range;
  16
  17         /* Out of slots: */
  18         if (nr_range >= az)
  19                 return nr_range;
  20
  21         range[nr_range].start = start;
  22         range[nr_range].end = end;
  23
  24         nr_range++;
  25
  26         return nr_range;
  27 }
  28
  29 int add_range_with_merge(struct range *range, int az, int nr_range,
  30                      u64 start, u64 end)
  31 {
  32         int i;
  33
  34         if (start >= end)
  35                 return nr_range;
  36
  37         /* get new start/end: */
  38         for (i = 0; i < nr_range; i++) {
  39                 u64 common_start, common_end;
  40
  41                 if (!range[i].end)
  42                         continue;
  43
  44                 common_start = max(range[i].start, start);
  45                 common_end = min(range[i].end, end);
  46                 if (common_start > common_end)
  47                         continue;
  48
  49                 /* new start/end, will add it back at last */
  50                 start = min(range[i].start, start);
  51                 end = max(range[i].end, end);
  52
  53                 memmove(&range[i], &range[i + 1],
  54                         (nr_range - (i + 1)) * sizeof(range[i]));
  55                 range[nr_range - 1].start = 0;
  56                 range[nr_range - 1].end   = 0;
  57                 nr_range--;
  58                 i--;
  59         }
  60
  61         /* Need to add it: */
  62         return add_range(range, az, nr_range, start, end);
  63 }
  64
  65 void subtract_range(struct range *range, int az, u64 start, u64 end)
  66 {
  67         int i, j;
  68
  69         if (start >= end)
  70                 return;
  71
  72         for (j = 0; j < az; j++) {
  73                 if (!range[j].end)
  74                         continue;
  75
  76                 if (start <= range[j].start && end >= range[j].end) {
  77                         range[j].start = 0;
  78                         range[j].end = 0;
  79                         continue;
  80                 }
  81
  82                 if (start <= range[j].start && end < range[j].end &&
  83                     range[j].start < end) {
  84                         range[j].start = end;
  85                         continue;
  86                 }
  87
  88
  89                 if (start > range[j].start && end >= range[j].end &&
  90                     range[j].end > start) {
  91                         range[j].end = start;
  92                         continue;
  93                 }
  94
  95                 if (start > range[j].start && end < range[j].end) {
  96                         /* Find the new spare: */
  97                         for (i = 0; i < az; i++) {
  98                                 if (range[i].end == 0)
  99                                         break;
 100                         }
 101                         if (i < az) {
 102                                 range[i].end = range[j].end;
 103                                 range[i].start = end;
 104                         } else {
 105                                 pr_err("%s: run out of slot in ranges\n",
 106                                         __func__);
 107                         }
 108                         range[j].end = start;
 109                         continue;
 110                 }
 111         }
 112 }
 113
 114 static int cmp_range(const void *x1, const void *x2)
 115 {
 116         const struct range *r1 = x1;
 117         const struct range *r2 = x2;
 118
 119         if (r1->start < r2->start)
 120                 return -1;
 121         if (r1->start > r2->start)
 122                 return 1;
 123         return 0;
 124 }
 125
 126 int clean_sort_range(struct range *range, int az)
 127 {
 128         int i, j, k = az - 1, nr_range = az;
 129
 130         for (i = 0; i < k; i++) {
 131                 if (range[i].end)
 132                         continue;
 133                 for (j = k; j > i; j--) {
 134                         if (range[j].end) {
 135                                 k = j;
 136                                 break;
 137                         }
 138                 }
 139                 if (j == i)
 140                         break;
 141                 range[i].start = range[k].start;
 142                 range[i].end   = range[k].end;
 143                 range[k].start = 0;
 144                 range[k].end   = 0;
 145                 k--;
 146         }
 147         /* count it */
 148         for (i = 0; i < az; i++) {
 149                 if (!range[i].end) {
 150                         nr_range = i;
 151                         break;
 152                 }
 153         }
 154
 155         /* sort them */
 156         sort(range, nr_range, sizeof(struct range), cmp_range, NULL);
 157
 158         return nr_range;
 159 }
 160
 161 void sort_range(struct range *range, int nr_range)
 162 {
 163         /* sort them */
 164         sort(range, nr_range, sizeof(struct range), cmp_range, NULL);
 165 }