tsymtab.c - plan9port - [fork] Plan 9 from user space
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       ---
       tsymtab.c (1587B)
       ---
            1 #include        "mk.h"
            2 
            3 #define        NHASH        4099
            4 #define        HASHMUL        79UL        /* this is a good value */
            5 static Symtab *hash[NHASH];
            6 
            7 void
            8 syminit(void)
            9 {
           10         Symtab **s, *ss, *next;
           11 
           12         for(s = hash; s < &hash[NHASH]; s++){
           13                 for(ss = *s; ss; ss = next){
           14                         next = ss->next;
           15                         free((char *)ss);
           16                 }
           17                 *s = 0;
           18         }
           19 }
           20 
           21 Symtab *
           22 symlook(char *sym, int space, void *install)
           23 {
           24         unsigned long h;
           25         char *p;
           26         Symtab *s;
           27 
           28         for(p = sym, h = space; *p; h += *p++)
           29                 h *= HASHMUL;
           30         h %= NHASH;
           31         for(s = hash[h]; s; s = s->next)
           32                 if((s->space == space) && (strcmp(s->name, sym) == 0))
           33                         return(s);
           34         if(install == 0)
           35                 return(0);
           36         s = (Symtab *)Malloc(sizeof(Symtab));
           37         s->space = space;
           38         s->name = sym;
           39         s->u.ptr = install;
           40         s->next = hash[h];
           41         hash[h] = s;
           42         return(s);
           43 }
           44 
           45 void
           46 symdel(char *sym, int space)
           47 {
           48         unsigned long h;
           49         char *p;
           50         Symtab *s, *ls;
           51 
           52         /* multiple memory leaks */
           53 
           54         for(p = sym, h = space; *p; h += *p++)
           55                 h *= HASHMUL;
           56         h %= NHASH;
           57         for(s = hash[h], ls = 0; s; ls = s, s = s->next)
           58                 if((s->space == space) && (strcmp(s->name, sym) == 0)){
           59                         if(ls)
           60                                 ls->next = s->next;
           61                         else
           62                                 hash[h] = s->next;
           63                         free((char *)s);
           64                 }
           65 }
           66 
           67 void
           68 symtraverse(int space, void (*fn)(Symtab*))
           69 {
           70         Symtab **s, *ss;
           71 
           72         for(s = hash; s < &hash[NHASH]; s++)
           73                 for(ss = *s; ss; ss = ss->next)
           74                         if(ss->space == space)
           75                                 (*fn)(ss);
           76 }
           77 
           78 void
           79 symstat(void)
           80 {
           81         Symtab **s, *ss;
           82         int n;
           83         int l[1000];
           84 
           85         memset((char *)l, 0, sizeof(l));
           86         for(s = hash; s < &hash[NHASH]; s++){
           87                 for(ss = *s, n = 0; ss; ss = ss->next)
           88                         n++;
           89                 l[n]++;
           90         }
           91         for(n = 0; n < 1000; n++)
           92                 if(l[n]) Bprint(&bout, "%ld of length %d\n", l[n], n);
           93 }