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Annotation of 43BSDReno/sys/nfs/TEST/billboard/src/bb_hash.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  ******************************************************************************
                      3:  *
                      4:  * Module: bb_hash.c
                      5:  *
                      6:  * Functions: 
                      7:  *         bb_put_hash()       - Place an entry in the hash table.
                      8:  *         bb_get_hash()       - Return an index from the hash table.
                      9:  *
                     10:  *
                     11:  ******************************************************************************
                     12:  */
                     13: 
                     14: /*
                     15:  ******************************************************************************
                     16:  * Include Files
                     17:  ******************************************************************************
                     18:  */
                     19: #include <stdio.h>
                     20: #include <rpc/rpc.h>
                     21: #include "common.h"
                     22: #include "protocol.h"
                     23: #include "server.h"
                     24: 
                     25: static BB_hash         bb_hash;        /* The hash table of id, index. */
                     26: static BB_co_data      bb_co_d[BB_MAX_IMP]; /* The company data table. */
                     27: 
                     28: int
                     29: bb_put_hash( id, index)
                     30:   BB_id                id;             /* The identifier to hash.              */
                     31:   int          index;          /* Index of this record in co. data tbl.*/
                     32: {
                     33:     int                i;              /* Nice loop variable name.             */
                     34:     int                hash_idx = 0;   /* Index into hash table.               */
                     35:     int                term_idx;       /* Termination index of circular search.*/
                     36: 
                     37:     /*
                     38:     **  Sum up all of the characters in the id and mod it by the
                     39:     **  hash list size.  This is the initial hash index.
                     40:     */
                     41:     for( i = 0; (id[i] != NUL) && (i < BB_ID_NAME_LEN); i++)
                     42:     {
                     43:        hash_idx += id[i];
                     44:     }
                     45:     hash_idx = term_idx = (hash_idx % BB_MAX_HASH);
                     46: 
                     47:     /*
                     48:     **  Search the table for the first open hash bucket.  If the hash
                     49:     **  table does not contain one break at the termination index.
                     50:     */
                     51:     while( bb_hash[hash_idx].id_ptr != NULL )
                     52:     {
                     53:        hash_idx = ((hash_idx + 1) % BB_MAX_HASH);
                     54:        if ( hash_idx == term_idx )
                     55:            break;
                     56:     }
                     57:     
                     58:     /*
                     59:     **  If the hash bucket is empty then install the info here.
                     60:     **  Otherwise the table is full.
                     61:     */
                     62:     if ( bb_hash[hash_idx].id_ptr == NULL )
                     63:     {
                     64:        bb_hash[hash_idx].index  = index;
                     65:        bb_hash[hash_idx].id_ptr = id;
                     66:        return BB_SUCCESS;
                     67:     }
                     68:     else
                     69:     {
                     70:        return BB_HASH_TABLE_FULL;
                     71:     }
                     72: }
                     73: 
                     74: int
                     75: bb_get_hash( id)
                     76:   BB_id                id;             /* The identifier to hash.              */
                     77: {
                     78:     int                i;              /* Nice loop variable name.             */
                     79:     int                hash_idx = 0;   /* Index into hash table.               */
                     80:     int                term_idx;       /* Termination index of circular search.*/
                     81: 
                     82:     /*
                     83:     **  Sum up all of the characters in the id and mod it by the
                     84:     **  hash list size.  This is the initial hash index.
                     85:     */
                     86:     for( i = 0; (id[i] != NUL) && (i < BB_ID_NAME_LEN); i++)
                     87:     {
                     88:        hash_idx += id[i];
                     89:     }
                     90:     hash_idx = term_idx = (hash_idx % BB_MAX_HASH);
                     91: 
                     92:     /*
                     93:     **  Search the hash table based upon the initial index.  The search
                     94:     **  ends when the index is found or one complete cycle of the hash
                     95:     **  table has been done.  This is linear resolution.
                     96:     */
                     97:     while( ( bb_hash[hash_idx].id_ptr != NULL ) && 
                     98:           ( strncmp( bb_hash[hash_idx].id_ptr, id, BB_ID_NAME_LEN) != 0 ) )
                     99:     {
                    100:        hash_idx = ((hash_idx + 1) % BB_MAX_HASH);
                    101:        if ( hash_idx == term_idx )
                    102:            break;
                    103:     }
                    104:     
                    105:     /*
                    106:     **  If the id is equal to that of the hash bucket then a match is 
                    107:     **  found.  Otherwise the table does not contain this id.
                    108:     */
                    109:     if ( ( bb_hash[hash_idx].id_ptr != NUL ) &&
                    110:         ( strncmp( bb_hash[hash_idx].id_ptr, id, BB_ID_NAME_LEN) == 0 ) )
                    111:     {
                    112:        return bb_hash[hash_idx].index;
                    113:     }
                    114:     else
                    115:     {
                    116:        return BB_HASH_ID_NOT_FOUND;
                    117:     }
                    118: }

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