kernel/range.c

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