decorate.c

   1 /*
   2  * decorate.c - decorate a git object with some arbitrary
   3  * data.
   4  */
   5 #include "cache.h"
   6 #include "object.h"
   7 #include "decorate.h"
   8
   9 static unsigned int hash_obj(const struct object *obj, unsigned int n)
  10 {
  11         unsigned int hash;
  12
  13         memcpy(&hash, obj->sha1, sizeof(unsigned int));
  14         return hash % n;
  15 }
  16
  17 static void *insert_decoration(struct decoration *n, const struct object *base, void *decoration)
  18 {
  19         int size = n->size;
  20         struct object_decoration *hash = n->hash;
  21         unsigned int j = hash_obj(base, size);
  22
  23         while (hash[j].base) {
  24                 if (hash[j].base == base) {
  25                         void *old = hash[j].decoration;
  26                         hash[j].decoration = decoration;
  27                         return old;
  28                 }
  29                 if (++j >= size)
  30                         j = 0;
  31         }
  32         hash[j].base = base;
  33         hash[j].decoration = decoration;
  34         n->nr++;
  35         return NULL;
  36 }
  37
  38 static void grow_decoration(struct decoration *n)
  39 {
  40         int i;
  41         int old_size = n->size;
  42         struct object_decoration *old_hash = n->hash;
  43
  44         n->size = (old_size + 1000) * 3 / 2;
  45         n->hash = xcalloc(n->size, sizeof(struct object_decoration));
  46         n->nr = 0;
  47
  48         for (i = 0; i < old_size; i++) {
  49                 const struct object *base = old_hash[i].base;
  50                 void *decoration = old_hash[i].decoration;
  51
  52                 if (!base)
  53                         continue;
  54                 insert_decoration(n, base, decoration);
  55         }
  56         free(old_hash);
  57 }
  58
  59 /* Add a decoration pointer, return any old one */
  60 void *add_decoration(struct decoration *n, const struct object *obj,
  61                 void *decoration)
  62 {
  63         int nr = n->nr + 1;
  64
  65         if (nr > n->size * 2 / 3)
  66                 grow_decoration(n);
  67         return insert_decoration(n, obj, decoration);
  68 }
  69
  70 /* Lookup a decoration pointer */
  71 void *lookup_decoration(struct decoration *n, const struct object *obj)
  72 {
  73         unsigned int j;
  74
  75         /* nothing to lookup */
  76         if (!n->size)
  77                 return NULL;
  78         j = hash_obj(obj, n->size);
  79         for (;;) {
  80                 struct object_decoration *ref = n->hash + j;
  81                 if (ref->base == obj)
  82                         return ref->decoration;
  83                 if (!ref->base)
  84                         return NULL;
  85                 if (++j == n->size)
  86                         j = 0;
  87         }
  88 }