src/runtime/vars.c

   1 /*
   2  * This software is part of the SBCL system. See the README file for
   3  * more information.
   4  *
   5  * This software is derived from the CMU CL system, which was
   6  * written at Carnegie Mellon University and released into the
   7  * public domain. The software is in the public domain and is
   8  * provided with absolutely no warranty. See the COPYING and CREDITS
   9  * files for more information.
  10  */
  11
  12 #include <stdio.h>
  13 #include <string.h>
  14 #include <sys/types.h>
  15 #include <stdlib.h>
  16
  17 #include "sbcl.h"
  18 #include "runtime.h"
  19 #include "vars.h"
  20 #include "os.h"
  21
  22 #define NAME_BUCKETS 31
  23 #define OBJ_BUCKETS 31
  24
  25 static struct var *NameHash[NAME_BUCKETS], *ObjHash[OBJ_BUCKETS];
  26 static int tempcntr = 1;
  27
  28 struct var {
  29     lispobj obj;
  30     lispobj (*update_fn)(struct var *var);
  31     char *name;
  32     long clock;
  33     boolean map_back, permanent;
  34
  35     struct var *nnext; /* Next in name list */
  36     struct var *onext; /* Next in object list */
  37 };
  38
  39 static int hash_name(char *name)
  40 {
  41     unsigned long value = 0;
  42
  43     while (*name != '\0') {
  44         value = (value << 1) ^ *(unsigned char *)(name++);
  45         value = (value & (1-(1<<24))) ^ (value >> 24);
  46     }
  47
  48     return value % NAME_BUCKETS;
  49 }
  50
  51 static int hash_obj(lispobj obj)
  52 {
  53     return (unsigned long)obj % OBJ_BUCKETS;
  54 }
  55
  56 void flush_vars()
  57 {
  58     int index;
  59     struct var *var, *next, *perm = NULL;
  60
  61     /* Note: all vars in the object hash table also appear in the name hash
  62      * table, so if we free everything in the name hash table, we free
  63      * everything in the object hash table. */
  64
  65     for (index = 0; index < NAME_BUCKETS; index++)
  66         for (var = NameHash[index]; var != NULL; var = next) {
  67             next = var->nnext;
  68             if (var->permanent) {
  69                 var->nnext = perm;
  70                 perm = var;
  71             }
  72             else {
  73                 free(var->name);
  74                 free(var);
  75             }
  76         }
  77     memset(NameHash, 0, sizeof(NameHash));
  78     memset(ObjHash, 0, sizeof(ObjHash));
  79     tempcntr = 1;
  80
  81     for (var = perm; var != NULL; var = next) {
  82         next = var->nnext;
  83         index = hash_name(var->name);
  84         var->nnext = NameHash[index];
  85         NameHash[index] = var;
  86         if (var->map_back) {
  87             index = hash_obj(var->obj);
  88             var->onext = ObjHash[index];
  89             ObjHash[index] = var;
  90         }
  91     }
  92 }
  93
  94 struct var *lookup_by_name(name)
  95 char *name;
  96 {
  97     struct var *var;
  98
  99     for (var = NameHash[hash_name(name)]; var != NULL; var = var->nnext)
 100         if (strcmp(var->name, name) == 0)
 101             return var;
 102     return NULL;
 103 }
 104
 105 struct var *lookup_by_obj(obj)
 106 lispobj obj;
 107 {
 108     struct var *var;
 109
 110     for (var = ObjHash[hash_obj(obj)]; var != NULL; var = var->onext)
 111         if (var->obj == obj)
 112             return var;
 113     return NULL;
 114 }
 115
 116 static struct var *make_var(char *name, boolean perm)
 117 {
 118     struct var *var = (struct var *)malloc(sizeof(struct var));
 119     char buffer[256];
 120     int index;
 121
 122     if (name == NULL) {
 123         sprintf(buffer, "%d", tempcntr++);
 124         name = buffer;
 125     }
 126     var->name = (char *)malloc(strlen(name)+1);
 127     strcpy(var->name, name);
 128     var->clock = 0;
 129     var->permanent = perm;
 130     var->map_back = 0;
 131
 132     index = hash_name(name);
 133     var->nnext = NameHash[index];
 134     NameHash[index] = var;
 135
 136     return var;
 137 }
 138
 139 struct var *define_var(char *name, lispobj obj, boolean perm)
 140 {
 141     struct var *var = make_var(name, perm);
 142     int index;
 143
 144     var->obj = obj;
 145     var->update_fn = NULL;
 146
 147     if (lookup_by_obj(obj) == NULL) {
 148         var->map_back = 1;
 149         index = hash_obj(obj);
 150         var->onext = ObjHash[index];
 151         ObjHash[index] = var;
 152     }
 153
 154     return var;
 155 }
 156
 157 struct var *define_dynamic_var(char *name, lispobj updatefn(struct var *),
 158                                boolean perm)
 159 {
 160     struct var *var = make_var(name, perm);
 161
 162     var->update_fn = updatefn;
 163
 164     return var;
 165 }
 166
 167 char *var_name(struct var *var)
 168 {
 169     return var->name;
 170 }
 171
 172 lispobj var_value(struct var *var)
 173 {
 174     if (var->update_fn != NULL)
 175         var->obj = (*var->update_fn)(var);
 176     return var->obj;
 177 }
 178
 179 long var_clock(struct var *var)
 180 {
 181     return var->clock;
 182 }
 183
 184 void var_setclock(struct var *var, long val)
 185 {
 186     var->clock = val;
 187 }