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0f4fcf2755064e7299449f44d3687f2f6ca0d715
   1#include "cache.h"
   2#include "prio-queue.h"
   3
   4static inline int compare(struct prio_queue *queue, int i, int j)
   5{
   6        int cmp = queue->compare(queue->array[i], queue->array[j],
   7                                 queue->cb_data);
   8        return cmp;
   9}
  10
  11static inline void swap(struct prio_queue *queue, int i, int j)
  12{
  13        void *tmp = queue->array[i];
  14        queue->array[i] = queue->array[j];
  15        queue->array[j] = tmp;
  16}
  17
  18void prio_queue_reverse(struct prio_queue *queue)
  19{
  20        int i, j;
  21
  22        if (queue->compare != NULL)
  23                die("BUG: prio_queue_reverse() on non-LIFO queue");
  24        for (i = 0; i <= (j = (queue->nr - 1) - i); i++)
  25                swap(queue, i, j);
  26}
  27
  28void clear_prio_queue(struct prio_queue *queue)
  29{
  30        free(queue->array);
  31        queue->nr = 0;
  32        queue->alloc = 0;
  33        queue->array = NULL;
  34}
  35
  36void prio_queue_put(struct prio_queue *queue, void *thing)
  37{
  38        int ix, parent;
  39
  40        /* Append at the end */
  41        ALLOC_GROW(queue->array, queue->nr + 1, queue->alloc);
  42        queue->array[queue->nr++] = thing;
  43        if (!queue->compare)
  44                return; /* LIFO */
  45
  46        /* Bubble up the new one */
  47        for (ix = queue->nr - 1; ix; ix = parent) {
  48                parent = (ix - 1) / 2;
  49                if (compare(queue, parent, ix) <= 0)
  50                        break;
  51
  52                swap(queue, parent, ix);
  53        }
  54}
  55
  56void *prio_queue_get(struct prio_queue *queue)
  57{
  58        void *result;
  59        int ix, child;
  60
  61        if (!queue->nr)
  62                return NULL;
  63        if (!queue->compare)
  64                return queue->array[--queue->nr]; /* LIFO */
  65
  66        result = queue->array[0];
  67        if (!--queue->nr)
  68                return result;
  69
  70        queue->array[0] = queue->array[queue->nr];
  71
  72        /* Push down the one at the root */
  73        for (ix = 0; ix * 2 + 1 < queue->nr; ix = child) {
  74                child = ix * 2 + 1; /* left */
  75                if (child + 1 < queue->nr &&
  76                    compare(queue, child, child + 1) >= 0)
  77                        child++; /* use right child */
  78
  79                if (compare(queue, ix, child) <= 0)
  80                        break;
  81
  82                swap(queue, child, ix);
  83        }
  84        return result;
  85}