| 1 | /* Copyright (c) 1982 Regents of the University of California */ |
| 2 | |
| 3 | static char sccsid[] = "@(#)names.c 1.3 %G%"; |
| 4 | |
| 5 | /* |
| 6 | * Name are the internal representation for identifiers. |
| 7 | * |
| 8 | * A hash table is used to map identifiers to names. |
| 9 | */ |
| 10 | |
| 11 | #include "defs.h" |
| 12 | #include "names.h" |
| 13 | |
| 14 | #ifndef public |
| 15 | typedef struct Name *Name; |
| 16 | |
| 17 | /* |
| 18 | * Inline (for speed) function to return the identifier (string) |
| 19 | * associated with a name. Because C cannot support both inlines |
| 20 | * and data hiding at the same time, the Name structure must be |
| 21 | * publicly visible. It is not used explicitly, however, outside of this file. |
| 22 | */ |
| 23 | |
| 24 | struct Name { |
| 25 | char *identifier; |
| 26 | Name chain; |
| 27 | }; |
| 28 | |
| 29 | #define ident(n) ((n == nil) ? "(noname)" : n->identifier) |
| 30 | #endif |
| 31 | |
| 32 | #define HASHTABLESIZE 2997 |
| 33 | |
| 34 | private Name nametable[HASHTABLESIZE]; |
| 35 | |
| 36 | /* |
| 37 | * Names are allocated in large chunks to avoid calls to malloc |
| 38 | * and to cluster names in memory so that tracing hash chains |
| 39 | * doesn't cause many a page fault. |
| 40 | */ |
| 41 | |
| 42 | #define CHUNKSIZE 200 |
| 43 | |
| 44 | typedef struct Namepool { |
| 45 | struct Name name[CHUNKSIZE]; |
| 46 | struct Namepool *prevpool; |
| 47 | } *Namepool; |
| 48 | |
| 49 | private Namepool namepool = nil; |
| 50 | private Integer nleft = 0; |
| 51 | |
| 52 | /* |
| 53 | * Given an identifier, convert it to a name. |
| 54 | * If it's not in the hash table, then put it there. |
| 55 | * |
| 56 | * The second argument specifies whether the string should be copied |
| 57 | * into newly allocated space if not found. |
| 58 | * |
| 59 | * Pardon my use of goto's, but it seemed more efficient and less convoluted |
| 60 | * than adding a collection of boolean variables. This routine is time |
| 61 | * critical when starting up the debugger on large programs. |
| 62 | */ |
| 63 | |
| 64 | public Name identname(s, isallocated) |
| 65 | String s; |
| 66 | Boolean isallocated; |
| 67 | { |
| 68 | register unsigned h; |
| 69 | register Char *p, *q; |
| 70 | register Name n; |
| 71 | register Integer len; |
| 72 | Namepool newpool; |
| 73 | |
| 74 | h = 0; |
| 75 | for (p = s; *p != '\0'; p++) { |
| 76 | h = (h << 1) ^ (*p); |
| 77 | } |
| 78 | h = h mod HASHTABLESIZE; |
| 79 | len = p - s; |
| 80 | n = nametable[h]; |
| 81 | while (n != nil) { |
| 82 | p = s; |
| 83 | q = n->identifier; |
| 84 | for (;;) { |
| 85 | if (*p != *q) { |
| 86 | goto nomatch; |
| 87 | } else if (*p == '\0') { |
| 88 | goto match; |
| 89 | } |
| 90 | ++p; |
| 91 | ++q; |
| 92 | } |
| 93 | nomatch: |
| 94 | n = n->chain; |
| 95 | } |
| 96 | |
| 97 | /* |
| 98 | * Now we know that name hasn't been found (otherwise we'd have jumped |
| 99 | * down to match), so we allocate a name, store the identifier, and |
| 100 | * enter it in the hash table. |
| 101 | */ |
| 102 | if (nleft <= 0) { |
| 103 | newpool = new(Namepool); |
| 104 | bzero(newpool, sizeof(newpool)); |
| 105 | newpool->prevpool = namepool; |
| 106 | namepool = newpool; |
| 107 | nleft = CHUNKSIZE; |
| 108 | } |
| 109 | --nleft; |
| 110 | n = &(namepool->name[nleft]); |
| 111 | if (isallocated) { |
| 112 | n->identifier = s; |
| 113 | } else { |
| 114 | n->identifier = newarr(char, len + 1); |
| 115 | p = s; |
| 116 | q = n->identifier; |
| 117 | while (*p != '\0') { |
| 118 | *q++ = *p++; |
| 119 | } |
| 120 | *q = '\0'; |
| 121 | } |
| 122 | n->chain = nametable[h]; |
| 123 | nametable[h] = n; |
| 124 | |
| 125 | /* |
| 126 | * The two possibilities (name known versus unknown) rejoin. |
| 127 | */ |
| 128 | match: |
| 129 | return n; |
| 130 | } |
| 131 | |
| 132 | /* |
| 133 | * Return the identifier associated with a name. |
| 134 | * |
| 135 | * Currently compiled inline. |
| 136 | * |
| 137 | * |
| 138 | * public String ident(n) |
| 139 | Name n; |
| 140 | { |
| 141 | return (n == nil) ? "(noname)" : n->identifier; |
| 142 | } |
| 143 | * |
| 144 | */ |
| 145 | |
| 146 | /* |
| 147 | * Deallocate the name table. |
| 148 | */ |
| 149 | |
| 150 | public names_free() |
| 151 | { |
| 152 | register int i; |
| 153 | register Name n, next; |
| 154 | |
| 155 | for (i = 0; i < HASHTABLESIZE; i++) { |
| 156 | n = nametable[i]; |
| 157 | while (n != nil) { |
| 158 | next = n->chain; |
| 159 | dispose(n); |
| 160 | n = next; |
| 161 | } |
| 162 | nametable[i] = nil; |
| 163 | } |
| 164 | namepool = nil; |
| 165 | nleft = 0; |
| 166 | } |