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