jvm/c/hash_table.c

#include <assert.h>

#include "malloc.h"
#include "hash_table.h"

static const uint32_t fnv_offset_basis = 0x811c9dc5;

static uint32_t fnv_1(uint32_t hash, const uint8_t * buf, int length)
{
  const uint32_t fnv_prime = 0x01000193;

  for (int i = 0; i < length; i++) {
    hash = hash * fnv_prime;
    hash = hash ^ buf[i];
  }

  return hash;
}

void hash_table_init(int hash_table_length,
                     struct hash_table_entry * entry)
{
  for (int i = 0; i < hash_table_length; i++) {
    entry[i].key = nullptr;
    entry[i].next = nullptr;
  }
}


#include <stdio.h>

void print_key(const uint8_t * key, int key_length)
{
  printf("key: ");
  for (int i = 0; i < key_length; i++)
    fputc(key[i], stdout);
  fputc('\n', stdout);
}

void hash_table_add(int hash_table_length,
                    struct hash_table_entry * entry,
                    const uint8_t * key,
                    int key_length,
                    void * value)
{
  assert(hash_table_length != 0);
  uint32_t hash = fnv_1(fnv_offset_basis, key, key_length) & (hash_table_length - 1);
  struct hash_table_entry * e = &entry[hash];

  while (e->next != nullptr) {
    e = e->next;
  }

  if (e->key != nullptr) {
    // allocate e from overflow
    e->next = malloc_class_arena((sizeof (struct hash_table_entry)));
    e = e->next;
  }

  uint8_t * key_copy = malloc_class_arena(key_length);
  for (int i = 0; i < key_length; i++) key_copy[i] = key[i];
  printf("key copy: %p ", key_copy);
  print_key(key_copy, key_length);

  e->key = key_copy;
  e->key_length = key_length;
  e->value = value;
}

static inline bool key_equal(const uint8_t * a, const uint8_t * b, int length)
{
  for (int i = 0; i < length; i++) {
    if (a[i] != b[i])
      return false;
  }
  return true;
}

struct hash_table_entry * hash_table_find(int hash_table_length,
                                          struct hash_table_entry * entry,
                                          const uint8_t * key,
                                          int key_length)
{
  assert(hash_table_length != 0);
  uint32_t hash = fnv_1(fnv_offset_basis, key, key_length) & (hash_table_length - 1);
  struct hash_table_entry * e = &entry[hash];

  while (e != nullptr && e->key != nullptr) {
    printf("key find: %p ", e->key);
    print_key(e->key, e->key_length);
    if (e->key_length == key_length && key_equal(key, e->key, e->key_length)) {
      return e;
    }
    e = e->next;
  }
  return nullptr;
}

static inline bool key_equal2(const uint8_t * a1, int a1_length,
                              const uint8_t * a2, int a2_length,
                              const uint8_t * b)
{
  for (int i = 0; i < a1_length; i++) {
    if (a1[i] != b[i])
      return false;
  }
  for (int i = 0; i < a2_length; i++) {
    if (a2[i] != b[a1_length + i])
      return false;
  }
  return true;
}

void hash_table_add2(int hash_table_length,
                     struct hash_table_entry * entry,
                     const uint8_t * key1,
                     int key1_length,
                     const uint8_t * key2,
                     int key2_length,
                     void * value)
{
  assert(hash_table_length != 0);
  uint32_t hash = fnv_offset_basis;
  hash = fnv_1(hash, key1, key1_length);
  hash = fnv_1(hash, key2, key2_length);
  hash &= (hash_table_length - 1);
  struct hash_table_entry * e = &entry[hash];

  while (e->next != nullptr) {
    e = e->next;
  }

  if (e->key != nullptr) {
    // allocate e from overflow
    e->next = malloc_class_arena((sizeof (struct hash_table_entry)));
    e = e->next;
  }

  uint8_t * key_copy = malloc_class_arena(key1_length + key2_length);
  for (int i = 0; i < key1_length; i++) key_copy[i] = key1[i];
  for (int i = 0; i < key2_length; i++) key_copy[key1_length + i] = key2[i];
  e->key = key_copy;
  e->key_length = key1_length + key2_length;
  e->value = value;
}

struct hash_table_entry * hash_table_find2(int hash_table_length,
                                           struct hash_table_entry * entry,
                                           const uint8_t * key1,
                                           int key1_length,
                                           const uint8_t * key2,
                                           int key2_length)
{
  assert(hash_table_length != 0);
  uint32_t hash = fnv_offset_basis;
  hash = fnv_1(hash, key1, key1_length);
  hash = fnv_1(hash, key2, key2_length);
  hash &= (hash_table_length - 1);

  struct hash_table_entry * e = &entry[hash];

  while (e != nullptr && e->key != nullptr) {
    bool equal =
      e->key_length == (key1_length + key2_length) &&
      key_equal2(key1, key1_length,
                 key2, key2_length,
                 e->key);
    if (equal) {
      return e;
    }
    e = e->next;
  }
  return nullptr;
}

/*
void hash_table_add_int(int hash_table_length,
                        struct hash_table_entry * entry,
                        int key,
                        void * value)
{
  hash_table_add(hash_table_length,
                 entry,
                 (const uint8_t *)&key,
                 4,
                 value);
}

struct hash_table_entry * hash_table_find_int(int hash_table_length,
                                              struct hash_table_entry * entry,
                                              int key)
{
  return hash_table_find(hash_table_length,
                         entry,
                         (const uint8_t *)&key,
                         4);
}
*/