60 lines
1.8 KiB
C
60 lines
1.8 KiB
C
#ifndef LIBLEX_PAIRMAP_H
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#define LIBLEX_PAIRMAP_H
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#define LIBLEX_PAIRMAP_SIZE 64
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/**
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* Since libds's hash table requires a pointer to a key object, it's necessary to modify a single
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* key object (tmp) with the two values for the pair, and then pass it into the ht_xxx functions
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* to be copied. This requires at least 3 things - set the x value, set the y value, call the
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* hash table function the requires the key. These macros take care of these three things.
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*/
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#define PAIRMAP_PUT(map, tmp, newx, newy, data) ((tmp)->x = newx, (tmp)->y = newy, ht_put(map, tmp, data))
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#define PAIRMAP_GET(map, tmp, newx, newy) ((tmp)->x = newx, (tmp)->y = newy, ht_get(map, tmp))
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#include "ht.h"
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/**
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* A key object used for hash tables that take a pair of integers
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* instead of a single pointer.
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*/
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struct pairmap_key_s {
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int x;
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int y;
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};
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typedef struct pairmap_key_s pairmap_key;
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/**
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* Hashes pairmap_key instead of the default string.
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* This takes the lower 16 bits, and bit shifts them
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* into a single integer.
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*
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* Why 16 bits? Well, the hash map implementation takes an unsigned long,
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* which is only guaranteed to contain 32 bits. Therefore, assuming it
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* has to be unique for any two equal-sized integers, it has to
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* be twice the size. Hence, the largest the integers can be is 16.
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* @param key the key for the hash table.
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* @return the resulting hash.
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*/
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unsigned long pairmap_hash_func(void* key);
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/**
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* Compares two pairmap_key's.
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* @param a the first pairmap_key
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* @param b the second pairmap_key
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* @return
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*/
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int pairmap_cmp_func(void* a, void* b);
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/**
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* Copies a pairmap_key.
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* @param key the key to copy.
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* @return the copy of the key.
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*/
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void* pairmap_copy_func(void* key);
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/**
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* Initializes a hash table with functions used for pair maps.
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* @param ht the hash table to initialize.
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*/
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void pairmap_init_ht(ht* ht);
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#endif
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