File: hash.c

package info (click to toggle)
mawk 1.3.3-17
  • links: PTS, VCS
  • area: main
  • in suites: buster, jessie, jessie-kfreebsd, stretch, wheezy
  • size: 1,484 kB
  • ctags: 1,506
  • sloc: ansic: 13,008; yacc: 994; awk: 629; makefile: 113; sh: 107
file content (258 lines) | stat: -rw-r--r-- 4,504 bytes parent folder | download | duplicates (8)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258

/********************************************
hash.c
copyright 1991, Michael D. Brennan

This is a source file for mawk, an implementation of
the AWK programming language.

Mawk is distributed without warranty under the terms of
the GNU General Public License, version 2, 1991.
********************************************/


/* $Log: hash.c,v $
 * Revision 1.3  1994/10/08  19:15:43  mike
 * remove SM_DOS
 *
 * Revision 1.2  1993/07/16  00:17:35  mike
 * cleanup
 *
 * Revision 1.1.1.1  1993/07/03	 18:58:14  mike
 * move source to cvs
 *
 * Revision 5.1	 1991/12/05  07:56:05  brennan
 * 1.1 pre-release
 *
*/


/* hash.c */

#include "mawk.h"
#include "memory.h"
#include "symtype.h"


unsigned
hash(s)
   register char *s ;
{
   register unsigned h = 0 ;

   while (*s)  h += h + *s++ ;
   return h ;
}

typedef struct hash
{
   struct hash *link ;
   SYMTAB symtab ;
} HASHNODE ;

static HASHNODE *PROTO(delete, (char *)) ;

static HASHNODE *hash_table[HASH_PRIME] ;

/*
insert a string in the symbol table.
Caller knows the symbol is not there
-- used for initialization
*/

SYMTAB *
insert(s)
   char *s ;
{
   register HASHNODE *p = ZMALLOC(HASHNODE) ;
   register unsigned h ;

   p->link = hash_table[h = hash(s) % HASH_PRIME] ;
   p->symtab.name = s ;
   hash_table[h] = p ;
   return &p->symtab ;
}

/* Find s in the symbol table,
   if not there insert it,  s must be dup'ed  */

SYMTAB *
find(s)
   char *s ;
{
   register HASHNODE *p ;
   HASHNODE *q ;
   unsigned h ;

   p = hash_table[h = hash(s) % HASH_PRIME] ;
   q = (HASHNODE *) 0 ;
   while (1)
   {
      if (!p)
      {
	 p = ZMALLOC(HASHNODE) ;
	 p->symtab.type = ST_NONE ;
	 p->symtab.name = strcpy(zmalloc(strlen(s) + 1), s) ;
	 break ;
      }

      if (strcmp(p->symtab.name, s) == 0)	/* found */
      {
	 if (!q)		/* already at the front */
	    return &p->symtab ;
	 else  /* delete from the list */
	 {
	    q->link = p->link ;	 break ; 
	 }
      }

      q = p ; p = p->link ;
   }
   /* put p on front of the list */
   p->link = hash_table[h] ;
   hash_table[h] = p ;
   return &p->symtab ;
}


/* remove a node from the hash table
   return a ptr to the node */

static unsigned last_hash ;

static HASHNODE *
delete(s)
   char *s ;
{
   register HASHNODE *p ;
   HASHNODE *q = (HASHNODE *) 0 ;
   unsigned h ;

   p = hash_table[last_hash = h = hash(s) % HASH_PRIME] ;
   while (p)
   {
      if (strcmp(p->symtab.name, s) == 0)	/* found */
      {
	 if (q)	 q->link = p->link ;
	 else  hash_table[h] = p->link ;
	 return p ;
      }
      else
      {
	 q = p ; p = p->link ; 
      }
   }

#ifdef	DEBUG			/* we should not ever get here */
   bozo("delete") ;
#endif
   return (HASHNODE *) 0 ;
}

/* when processing user functions,  global ids which are
   replaced by local ids are saved on this list */

static HASHNODE *save_list ;

/* store a global id on the save list,
   return a ptr to the local symtab  */
SYMTAB *
save_id(s)
   char *s ;
{
   HASHNODE *p, *q ;
   unsigned h ;

   p = delete(s) ;
   q = ZMALLOC(HASHNODE) ;
   q->symtab.type = ST_LOCAL_NONE ;
   q->symtab.name = p->symtab.name ;
   /* put q in the hash table */
   q->link = hash_table[h = last_hash] ;
   hash_table[h] = q ;

   /* save p */
   p->link = save_list ; save_list = p ;

   return &q->symtab ;
}

/* restore all global indentifiers */
void
restore_ids()
{
   register HASHNODE *p, *q ;
   register unsigned h ;

   q = save_list ; save_list = (HASHNODE *) 0 ;
   while (q)
   {
      p = q ; q = q->link ;
      zfree(delete(p->symtab.name), sizeof(HASHNODE)) ;
      p->link = hash_table[h = last_hash] ;
      hash_table[h] = p ;
   }
}


/* search the symbol table backwards for the
   disassembler.  This is slow -- so what
*/


char *
reverse_find(type, ptr)
   int type ;
   PTR ptr ;
{
   CELL *cp ;
   ARRAY array ;
   static char uk[] = "unknown" ;

   int i ;
   HASHNODE *p ;


   switch (type)
   {
      case ST_VAR:
      case ST_FIELD:
	 cp = *(CELL **) ptr ;
	 break ;

      case ST_ARRAY:
	 array = *(ARRAY *) ptr ;
	 break ;

      default:
	 return uk ;
   }

   for (i = 0; i < HASH_PRIME; i++)
   {
      p = hash_table[i] ;
      while (p)
      {
	 if (p->symtab.type == type)
	 {
	    switch (type)
	    {
	       case ST_VAR:
	       case ST_FIELD:
		  if (cp == p->symtab.stval.cp)
		     return p->symtab.name ;
		  break ;

	       case ST_ARRAY:
		  if (array == p->symtab.stval.array)
		     return p->symtab.name ;
		  break ;
	    }
	 }

	 p = p->link ;
      }
   }
   return uk ;
}