projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| bb780e4a C |
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 | } |