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#include <string.h>
#include <stdio.h>
#include "ht.h"
#define HT_REHASH_THRESHOLD 0.5
struct ht_s {
NUM *keys;
void **values;
UNUM capability;
/* REVIEW: What is the purpose of SIZE? */
int size;
};
/* SIZE is a hint to the number of elements that might be put in the
table. In fact we will allocate more memory than this number, as a
hash table works better if it is not fully used. */
ht *
new_ht(UNUM size)
{
ht *htp = MYALLOC(ht, 1);
if (htp == NULL) {
fleprintf0("Fail to malloc\n");
return NULL;
}
htp->capability = (size<<1)+(size>>1);
htp->size = 0;
htp->keys = MYALLOC(NUM, htp->capability);
if (htp->keys == NULL) {
fleprintf0("Fail to malloc\n");
free(htp);
return NULL;
}
htp->values = MYALLOC(void*, htp->capability);
if (htp->values == NULL) {
fleprintf0("Fail to malloc\n");
free(htp->keys);
free(htp);
return NULL;
}
/* Initialize the keys to be -1 and the values to be NULL */
memset(htp->keys, 0xff, sizeof (NUM) * htp->capability);
memset(htp->values, 0, sizeof (NUM) * htp->capability);
return htp;
}
void
destroy_ht(ht * restrict htp, int flag)
{
switch (flag) {
case 1:
for (UNUM i = 0; i < htp->capability;)
free(*(htp->values+i++));
break;
case 2:
free(*(htp->values));
break;
default:
break;
}
free(htp->values);
free(htp->keys);
free(htp);
}
static BOOL
ht_expand(ht *htp)
{
NUM oldcap = htp->capability;
htp->capability <<= 1;
htp->capability++;
NUM *newkeys = realloc(htp->keys, htp->capability);
if (newkeys == NULL) {
fleprintf0("Fail to realloc\n");
return 1;
}
htp->keys = newkeys;
memset(htp->keys+oldcap, 0xff,
sizeof (NUM) * (htp->capability - oldcap));
void **newvalues = realloc(htp->values, htp->capability);
if (newvalues == NULL) {
fleprintf0("Fail to realloc\n");
return 1;
}
htp->values = newvalues;
memset(htp->values+oldcap, 0,
sizeof(NUM) * (htp->capability - oldcap));
return 0;
}
BOOL
ht_insert(ht *htp, NUM key, void *value)
{
if (htp->size+1 >= HT_REHASH_THRESHOLD * htp->capability)
ht_expand(htp);
NUM ikey = key % htp->capability;
/* linear probing */
for (NUM count = 0;
count < htp->capability * HT_REHASH_THRESHOLD &&
*(htp->keys+ikey) > 0 &&
*(htp->keys+ikey) != key;
count++)
ikey = (ikey + 1) % htp->capability;
if (*(htp->keys+ikey) < 0) {
/* not inserted before */
*(htp->keys+ikey) = key;
*(htp->values+ikey) = value;
(htp->size)++;
} else if (*(htp->keys+ikey) == key) {
*(htp->values+ikey) = value;
} else {
fleprintf("Fail to probe an appropriate slot for %ld, "
"the result ikey = %ld\n",
key, ikey);
return 1;
}
/* fleprintf("ikey = %ld, size = %d, capability = %llu\n",
* ikey, htp->size, htp->capability); */
return 0;
}
BOOL
ht_delete(ht * const restrict htp, NUM key, int flag)
{
NUM ikey = key % htp->capability;
/* linear probing */
for (NUM count = 0;
count < htp->capability * HT_REHASH_THRESHOLD &&
*(htp->keys+ikey) > 0 &&
*(htp->keys+ikey) != key;
count++)
ikey = (ikey + 1) % htp->capability;
if (*(htp->keys+ikey) < 0) {
/* not inserted before */
return 0;
} else if (*(htp->keys+ikey) == key) {
(htp->size)--;
*(htp->keys+ikey) = -1;
if (flag) {
free(*(htp->values+ikey));
*(htp->values+ikey) = NULL;
}
return 0;
} else {
fleprintf("Fail to probe an appropriate slot for %ld, "
"the result ikey = %ld\n",
key, ikey);
return 1;
}
return 0;
}
void *
ht_find(ht * const restrict htp, NUM key)
{
NUM ikey = key % htp->capability;
/* linear probing */
for (NUM count = 0;
count < htp->capability * HT_REHASH_THRESHOLD &&
*(htp->keys+ikey) > 0 &&
*(htp->keys+ikey) != key;
count++)
ikey = (ikey + 1) % htp->capability;
if (*(htp->keys+ikey) == key)
return *(htp->values+ikey);
else if (*(htp->keys+ikey) > 0)
fleprintf("Fail to probe an appropriate slot for %ld, "
"with the result ikey = %ld\n",
key, ikey);
return NULL;
}
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