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mmeineke |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include "BASS_parse.h" |
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#define HASH_SIZE 211 // the size of the hash table |
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#define SHIFT 4 // the bit shift for the hash index calculation |
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//*** Global functions, variables, and structures ************ |
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unsigned short is_initialized = 0; // tells whether to init the linked list |
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// reserved word elements for the hash table |
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struct res_element{ |
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char word[100]; //the reserved word |
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int token; //the token to return; |
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struct res_element* next; |
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}; |
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struct res_element** reserved = NULL; //the table of reserved words |
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void initialize_res_list(void); // function to initialize the list |
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int hash ( char* text ); // generates the hash key |
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void add_res_element( char* text, int the_token ); //adds elements to the table |
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// the elements of the defined Hash table |
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struct defined_element{ |
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char defined[100]; |
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char definition[DEFINED_BUFFER_SIZE]; |
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struct defined_element* next; |
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}; |
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struct defined_element** defined_list = NULL; // the defined hash table |
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//*** The Functions ******************************************* |
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/* |
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function to initialize the list of reserved words into memory. |
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*/ |
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void initialize_res_list(){ |
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register unsigned short i; // loop counter |
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reserved = ( struct res_element ** ) |
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calloc( HASH_SIZE, sizeof( struct hash__element* ) ); |
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for( i=0; i < HASH_SIZE; i++ ){ |
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reserved[i] = NULL; |
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} |
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// add the reserved words |
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add_res_element( "molecule", MOLECULE ); |
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add_res_element( "atom", ATOM ); |
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add_res_element( "bond", BOND ); |
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add_res_element( "bend", BEND ); |
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add_res_element( "torsion", TORSION ); |
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add_res_element( "position", POSITION ); |
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add_res_element( "members", MEMBERS ); |
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add_res_element( "constraint", CONSTRAINT ); |
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add_res_element( "component", COMPONENT ); |
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add_res_element( "startIndex", START_INDEX ); |
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add_res_element( "orientation", ORIENTATION ); |
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is_initialized = 1; // set the initialization boolean to true |
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} |
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/* |
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checks for reserved words. |
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If a reserved word is found, returns the token, |
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else returns 0. |
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*/ |
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int res_word( char* text ){ |
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register unsigned short int i; // loop counter |
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int matched = 0; |
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int key; // the hash key |
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struct res_element* current_ptr; // points to the current hash element |
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struct defined_element* def_ptr; // points to the current define element |
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if( !is_initialized ){ // initialize the list if not already done |
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initialize_res_list(); |
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} |
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// get the hash key |
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key = hash( text ); |
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current_ptr = reserved[key]; |
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// walk through possible mutiple entries |
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while( current_ptr != NULL ){ |
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matched = !strcmp( text, current_ptr->word ); |
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if( matched ) return current_ptr->token; // search successful |
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current_ptr = current_ptr->next; |
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} |
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// if no keywords turn up, check the word against the list of defines |
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if( defined_list != NULL ){ |
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def_ptr = defined_list[key]; |
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while( def_ptr != NULL ){ |
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matched = !strcmp( text, def_ptr->defined ); |
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if( matched ) return DEFINED; |
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def_ptr = def_ptr->next; |
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} |
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} |
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return 0; //search failed |
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} |
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/* |
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* This is used to test whether a given word is defined |
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* returns 1 if true, 0 if False. |
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*/ |
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int is_defined( char* text ){ |
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int matched = 0; |
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int key; |
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struct defined_element* def_ptr; // points to the current define element |
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key = hash( text ); |
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if( defined_list != NULL ){ |
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def_ptr = defined_list[key]; |
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while( def_ptr != NULL ){ |
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matched = !strcmp( text, def_ptr->defined ); |
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if( matched ) return 1; // search succesful |
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def_ptr = def_ptr->next; |
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} |
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} |
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return 0; //search failed |
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} |
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/* |
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* The next bit returns the text to substitute for any given define. |
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*/ |
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char* get_definition( char* defined ){ |
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int key; |
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int matched = 0; |
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struct defined_element* def_ptr; |
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if( defined_list != NULL ){ |
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key = hash( defined ); |
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def_ptr = defined_list[key]; |
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while( def_ptr != NULL ){ |
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matched = !strcmp( defined, def_ptr->defined ); |
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if( matched ) return def_ptr->definition; |
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def_ptr = def_ptr->next; |
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} |
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} |
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// search failed, therefore there is an error |
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fprintf( stderr, "%s was not found in the defined list\n", defined ); |
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exit(1); |
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} |
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/* |
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* Add a define statement to the hash table |
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*/ |
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void insert_define( char* defined, char* definition ){ |
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int i, key; |
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struct defined_element* element; |
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if( defined_list == NULL ){ |
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defined_list = ( struct defined_element** ) |
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calloc( HASH_SIZE, sizeof( struct defined_element* ) ); |
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for( i=0; i<HASH_SIZE; i++ ){ |
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defined_list[i] = NULL; |
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} |
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} |
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key = hash( defined ); |
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element = (struct defined_element* ) |
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malloc( sizeof( struct defined_element ) ); |
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// fill the element |
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strcpy( element->defined, defined ); |
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strcpy( element->definition, definition ); |
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// add the element to the table |
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element->next = defined_list[key]; |
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defined_list[key] = element; |
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} |
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/* |
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* adds an element to the hash table |
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*/ |
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void add_res_element( char* text, int the_token ){ |
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int key; // the calculated hash key; |
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struct res_element* element; // the element being added |
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key = hash( text ); |
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element = (struct res_element *) malloc( sizeof( struct res_element ) ); |
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// fill the element |
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strcpy( element->word, text ); |
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element->token = the_token; |
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// add the element to the table |
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element->next = reserved[key]; |
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reserved[key] = element; |
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} |
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/* |
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generartes the hash key from the given word. |
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*/ |
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int hash ( char* text ){ |
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register unsigned short int i = 0; // loop counter |
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int key = 0; // the hash key |
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while( text[i] != '\0' ){ |
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key = ( ( key << SHIFT ) + text[i] ) % HASH_SIZE; |
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i++; |
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} |
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if( key < 0 ){ |
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// if the key is less than zero, we've had an overflow error |
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fprintf( stderr, |
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"There has been an overflow error in the hash key."); |
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exit(0); |
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} |
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return key; |
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} |
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/* |
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function to clean up the memory after we are finished with the lists |
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*/ |
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void kill_lists( ){ |
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struct res_element* current_res_ptr; |
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struct res_element* temp_res_ptr; |
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struct defined_element* current_def_ptr; |
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struct defined_element* temp_def_ptr; |
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register unsigned short int i; |
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if( reserved != NULL ){ |
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for( i=0; i < HASH_SIZE; i++){ |
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current_res_ptr = reserved[i]; |
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while( current_res_ptr != NULL ){ |
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temp_res_ptr = current_res_ptr->next; |
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free( current_res_ptr ); |
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current_res_ptr = temp_res_ptr; |
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} |
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} |
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free( reserved ); |
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} |
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if( defined_list != NULL ){ |
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for( i=0; i < HASH_SIZE; i++){ |
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current_def_ptr = defined_list[i]; |
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while( current_def_ptr != NULL ){ |
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temp_def_ptr = current_def_ptr->next; |
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free( current_def_ptr ); |
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current_def_ptr = temp_def_ptr; |
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} |
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} |
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free( defined_list ); |
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} |
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reserved = NULL; |
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defined_list = NULL; |
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is_initialized = 0; // initialization is now false |
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} |