104 lines
3.7 KiB
C
104 lines
3.7 KiB
C
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#ifndef __LIB_KERNEL_HASH_H
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#define __LIB_KERNEL_HASH_H
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/* Hash table.
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This data structure is thoroughly documented in the Tour of
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Pintos for Project 3.
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This is a standard hash table with chaining. To locate an
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element in the table, we compute a hash function over the
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element's data and use that as an index into an array of
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doubly linked lists, then linearly search the list.
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The chain lists do not use dynamic allocation. Instead, each
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structure that can potentially be in a hash must embed a
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struct hash_elem member. All of the hash functions operate on
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these `struct hash_elem's. The hash_entry macro allows
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conversion from a struct hash_elem back to a structure object
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that contains it. This is the same technique used in the
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linked list implementation. Refer to lib/kernel/list.h for a
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detailed explanation. */
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include "list.h"
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/* Hash element. */
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struct hash_elem
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{
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struct list_elem list_elem;
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};
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/* Converts pointer to hash element HASH_ELEM into a pointer to
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the structure that HASH_ELEM is embedded inside. Supply the
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name of the outer structure STRUCT and the member name MEMBER
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of the hash element. See the big comment at the top of the
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file for an example. */
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#define hash_entry(HASH_ELEM, STRUCT, MEMBER) \
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((STRUCT *) ((uint8_t *) &(HASH_ELEM)->list_elem \
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- offsetof (STRUCT, MEMBER.list_elem)))
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/* Computes and returns the hash value for hash element E, given
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auxiliary data AUX. */
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typedef unsigned hash_hash_func (const struct hash_elem *e, void *aux);
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/* Compares the value of two hash elements A and B, given
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auxiliary data AUX. Returns true if A is less than B, or
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false if A is greater than or equal to B. */
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typedef bool hash_less_func (const struct hash_elem *a,
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const struct hash_elem *b,
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void *aux);
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/* Performs some operation on hash element E, given auxiliary
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data AUX. */
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typedef void hash_action_func (struct hash_elem *e, void *aux);
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/* Hash table. */
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struct hash
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{
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size_t elem_cnt; /* Number of elements in table. */
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size_t bucket_cnt; /* Number of buckets, a power of 2. */
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struct list *buckets; /* Array of `bucket_cnt' lists. */
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hash_hash_func *hash; /* Hash function. */
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hash_less_func *less; /* Comparison function. */
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void *aux; /* Auxiliary data for `hash' and `less'. */
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};
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/* A hash table iterator. */
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struct hash_iterator
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{
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struct hash *hash; /* The hash table. */
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struct list *bucket; /* Current bucket. */
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struct hash_elem *elem; /* Current hash element in current bucket. */
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};
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/* Basic life cycle. */
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bool hash_init (struct hash *, hash_hash_func *, hash_less_func *, void *aux);
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void hash_clear (struct hash *, hash_action_func *);
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void hash_destroy (struct hash *, hash_action_func *);
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/* Search, insertion, deletion. */
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struct hash_elem *hash_insert (struct hash *, struct hash_elem *);
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struct hash_elem *hash_replace (struct hash *, struct hash_elem *);
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struct hash_elem *hash_find (struct hash *, struct hash_elem *);
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struct hash_elem *hash_delete (struct hash *, struct hash_elem *);
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/* Iteration. */
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void hash_apply (struct hash *, hash_action_func *);
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void hash_first (struct hash_iterator *, struct hash *);
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struct hash_elem *hash_next (struct hash_iterator *);
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struct hash_elem *hash_cur (struct hash_iterator *);
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/* Information. */
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size_t hash_size (struct hash *);
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bool hash_empty (struct hash *);
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/* Sample hash functions. */
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unsigned hash_bytes (const void *, size_t);
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unsigned hash_string (const char *);
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unsigned hash_int (int);
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#endif /* lib/kernel/hash.h */
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