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binutils-gdb/gas/hash.c

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Initial revision
1991-04-04 20:19:53 +02:00
/* hash.c - hash table lookup strings -
Copyright (C) 1987, 1990, 1991 Free Software Foundation, Inc.
This file is part of GAS, the GNU Assembler.
GAS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 1, or (at your option)
any later version.
GAS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GAS; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
/* static const char rcsid[] = "$Id$"; */
/*
* BUGS, GRIPES, APOLOGIA etc.
*
* A typical user doesn't need ALL this: I intend to make a library out
* of it one day - Dean Elsner.
* Also, I want to change the definition of a symbol to (address,length)
* so I can put arbitrary binary in the names stored. [see hsh.c for that]
*
* This slime is common coupled inside the module. Com-coupling (and other
* vandalism) was done to speed running time. The interfaces at the
* module's edges are adequately clean.
*
* There is no way to (a) run a test script through this heap and (b)
* compare results with previous scripts, to see if we have broken any
* code. Use GNU (f)utilities to do this. A few commands assist test.
* The testing is awkward: it tries to be both batch & interactive.
* For now, interactive rules!
*/
/*
* The idea is to implement a symbol table. A test jig is here.
* Symbols are arbitrary strings; they can't contain '\0'.
* [See hsh.c for a more general symbol flavour.]
* Each symbol is associated with a char*, which can point to anything
* you want, allowing an arbitrary property list for each symbol.
*
* The basic operations are:
*
* new creates symbol table, returns handle
* find (symbol) returns char*
* insert (symbol,char*) error if symbol already in table
* delete (symbol) returns char* if symbol was in table
* apply so you can delete all symbols before die()
* die destroy symbol table (free up memory)
*
* Supplementary functions include:
*
* say how big? what % full?
* replace (symbol,newval) report previous value
* jam (symbol,value) assert symbol:=value
*
* You, the caller, have control over errors: this just reports them.
*
* This package requires malloc(), free().
* Malloc(size) returns NULL or address of char[size].
* Free(address) frees same.
*/
/*
* The code and its structures are re-enterent.
* Before you do anything else, you must call hash_new() which will
* return the address of a hash-table-control-block (or NULL if there
* is not enough memory). You then use this address as a handle of the
* symbol table by passing it to all the other hash_...() functions.
* The only approved way to recover the memory used by the symbol table
* is to call hash_die() with the handle of the symbol table.
*
* Before you call hash_die() you normally delete anything pointed to
* by individual symbols. After hash_die() you can't use that symbol
* table again.
*
* The char* you associate with a symbol may not be NULL (0) because
* NULL is returned whenever a symbol is not in the table. Any other
* value is OK, except DELETED, #defined below.
*
* When you supply a symbol string for insertion, YOU MUST PRESERVE THE
* STRING until that symbol is deleted from the table. The reason is that
* only the address you supply, NOT the symbol string itself, is stored
* in the symbol table.
*
* You may delete and add symbols arbitrarily.
* Any or all symbols may have the same 'value' (char *). In fact, these
* routines don't do anything with your symbol values.
*
* You have no right to know where the symbol:char* mapping is stored,
* because it moves around in memory; also because we may change how it
* works and we don't want to break your code do we? However the handle
* (address of struct hash_control) is never changed in
* the life of the symbol table.
*
* What you CAN find out about a symbol table is:
* how many slots are in the hash table?
* how many slots are filled with symbols?
* (total hashes,collisions) for (reads,writes) (*)
* All of the above values vary in time.
* (*) some of these numbers will not be meaningful if we change the
* internals.
*/
/*
* I N T E R N A L
*
* Hash table is an array of hash_entries; each entry is a pointer to a
* a string and a user-supplied value 1 char* wide.
*
* The array always has 2 ** n elements, n>0, n integer.
* There is also a 'wall' entry after the array, which is always empty
* and acts as a sentinel to stop running off the end of the array.
* When the array gets too full, we create a new array twice as large
* and re-hash the symbols into the new array, then forget the old array.
* (Of course, we copy the values into the new array before we junk the
* old array!)
*
*/
#include <stdio.h>
#ifndef FALSE
#define FALSE (0)
#define TRUE (!FALSE)
#endif /* no FALSE yet */
#include <ctype.h>
#define min(a, b) ((a) < (b) ? (a) : (b))
#include "as.h"
#define error as_fatal
#define DELETED ((char *)1) /* guarenteed invalid address */
#define START_POWER (11) /* power of two: size of new hash table *//* JF was 6 */
/* JF These next two aren't used any more. */
/* #define START_SIZE (64) / * 2 ** START_POWER */
/* #define START_FULL (32) / * number of entries before table expands */
#define islive(ptr) (ptr->hash_string && ptr->hash_string!=DELETED)
/* above TRUE if a symbol is in entry @ ptr */
#define STAT_SIZE (0) /* number of slots in hash table */
/* the wall does not count here */
/* we expect this is always a power of 2 */
#define STAT_ACCESS (1) /* number of hash_ask()s */
#define STAT__READ (0) /* reading */
#define STAT__WRITE (1) /* writing */
#define STAT_COLLIDE (3) /* number of collisions (total) */
/* this may exceed STAT_ACCESS if we have */
/* lots of collisions/access */
#define STAT_USED (5) /* slots used right now */
#define STATLENGTH (6) /* size of statistics block */
#if STATLENGTH != HASH_STATLENGTH
Panic! Please make #include "stat.h" agree with previous definitions!
#endif
/* #define SUSPECT to do runtime checks */
/* #define TEST to be a test jig for hash...() */
#ifdef TEST /* TEST: use smaller hash table */
#undef START_POWER
#define START_POWER (3)
#undef START_SIZE
#define START_SIZE (8)
#undef START_FULL
#define START_FULL (4)
#endif
/*------------------ plan ---------------------------------- i = internal
struct hash_control * c;
struct hash_entry * e; i
int b[z]; buffer for statistics
z size of b
char * s; symbol string (address) [ key ]
char * v; value string (address) [datum]
boolean f; TRUE if we found s in hash table i
char * t; error string; "" means OK
int a; access type [0...n) i
c=hash_new () create new hash_control
hash_die (c) destroy hash_control (and hash table)
table should be empty.
doesn't check if table is empty.
c has no meaning after this.
hash_say (c,b,z) report statistics of hash_control.
also report number of available statistics.
v=hash_delete (c,s) delete symbol, return old value if any.
ask() NULL means no old value.
f
v=hash_replace (c,s,v) replace old value of s with v.
ask() NULL means no old value: no table change.
f
t=hash_insert (c,s,v) insert (s,v) in c.
ask() return error string.
f it is an error to insert if s is already
in table.
if any error, c is unchanged.
t=hash_jam (c,s,v) assert that new value of s will be v. i
ask() it may decide to GROW the table. i
f i
grow() i
t=hash_grow (c) grow the hash table. i
jam() will invoke JAM. i
?=hash_apply (c,y) apply y() to every symbol in c.
y evtries visited in 'unspecified' order.
v=hash_find (c,s) return value of s, or NULL if s not in c.
ask()
f
f,e=hash_ask() (c,s,a) return slot where s SHOULD live. i
code() maintain collision stats in c. i
.=hash_code (c,s) compute hash-code for s, i
from parameters of c. i
*/
static char hash_found; /* returned by hash_ask() to stop extra */
/* testing. hash_ask() wants to return both */
/* a slot and a status. This is the status. */
/* TRUE: found symbol */
/* FALSE: absent: empty or deleted slot */
/* Also returned by hash_jam(). */
/* TRUE: we replaced a value */
/* FALSE: we inserted a value */
static struct hash_entry * hash_ask();
static int hash_code ();
static char * hash_grow();
/*
* h a s h _ n e w ( )
*
*/
struct hash_control *
hash_new() /* create a new hash table */
/* return NULL if failed */
/* return handle (address of struct hash) */
{
register struct hash_control * retval;
register struct hash_entry * room; /* points to hash table */
register struct hash_entry * wall;
register struct hash_entry * entry;
register int * ip; /* scan stats block of struct hash_control */
register int * nd; /* limit of stats block */
if (( room = (struct hash_entry *) malloc( sizeof(struct
hash_entry)*((1<<START_POWER) + 1) ) ) != NULL)
/* +1 for the wall entry */
{
if (( retval = (struct hash_control *) malloc(sizeof(struct
hash_control)) ) != NULL)
{
nd = retval->hash_stat + STATLENGTH;
for (ip=retval->hash_stat; ip<nd; ip++)
{
*ip = 0;
}
retval -> hash_stat[STAT_SIZE] = 1<<START_POWER;
retval -> hash_mask = (1<<START_POWER) - 1;
retval -> hash_sizelog = START_POWER;
/* works for 1's compl ok */
retval -> hash_where = room;
retval -> hash_wall =
wall = room + (1<<START_POWER);
retval -> hash_full = (1<<START_POWER)/2;
for (entry=room; entry<=wall; entry++)
{
entry->hash_string = NULL;
}
}
}
else
{
retval = NULL; /* no room for table: fake a failure */
}
return(retval); /* return NULL or set-up structs */
}
/*
* h a s h _ d i e ( )
*
* Table should be empty, but this is not checked.
* To empty the table, try hash_apply()ing a symbol deleter.
* Return to free memory both the hash table and it's control
* block.
* 'handle' has no meaning after this function.
* No errors are recoverable.
*/
void
hash_die(handle)
struct hash_control * handle;
{
free((char *)handle->hash_where);
free((char *)handle);
}
/*
* h a s h _ s a y ( )
*
* Return the size of the statistics table, and as many statistics as
* we can until either (a) we have run out of statistics or (b) caller
* has run out of buffer.
* NOTE: hash_say treats all statistics alike.
* These numbers may change with time, due to insertions, deletions
* and expansions of the table.
* The first "statistic" returned is the length of hash_stat[].
* Then contents of hash_stat[] are read out (in ascending order)
* until your buffer or hash_stat[] is exausted.
*/
void
hash_say(handle,buffer,bufsiz)
register struct hash_control * handle;
register int buffer[/*bufsiz*/];
register int bufsiz;
{
register int * nd; /* limit of statistics block */
register int * ip; /* scan statistics */
ip = handle -> hash_stat;
nd = ip + min(bufsiz-1,STATLENGTH);
if (bufsiz>0) /* trust nothing! bufsiz<=0 is dangerous */
{
*buffer++ = STATLENGTH;
for (; ip<nd; ip++,buffer++)
{
*buffer = *ip;
}
}
}
/*
* h a s h _ d e l e t e ( )
*
* Try to delete a symbol from the table.
* If it was there, return its value (and adjust STAT_USED).
* Otherwise, return NULL.
* Anyway, the symbol is not present after this function.
*
*/
char * /* NULL if string not in table, else */
/* returns value of deleted symbol */
hash_delete(handle,string)
register struct hash_control * handle;
register char * string;
{
register char * retval; /* NULL if string not in table */
register struct hash_entry * entry; /* NULL or entry of this symbol */
entry = hash_ask(handle,string,STAT__WRITE);
if (hash_found)
{
retval = entry -> hash_value;
entry -> hash_string = DELETED; /* mark as deleted */
handle -> hash_stat[STAT_USED] -= 1; /* slots-in-use count */
#ifdef SUSPECT
if (handle->hash_stat[STAT_USED]<0)
{
error("hash_delete");
}
#endif /* def SUSPECT */
}
else
{
retval = NULL;
}
return(retval);
}
/*
* h a s h _ r e p l a c e ( )
*
* Try to replace the old value of a symbol with a new value.
* Normally return the old value.
* Return NULL and don't change the table if the symbol is not already
* in the table.
*/
char *
hash_replace(handle,string,value)
register struct hash_control * handle;
register char * string;
register char * value;
{
register struct hash_entry * entry;
register char * retval;
entry = hash_ask(handle,string,STAT__WRITE);
if (hash_found)
{
retval = entry -> hash_value;
entry -> hash_value = value;
}
else
{
retval = NULL;
}
;
return (retval);
}
/*
* h a s h _ i n s e r t ( )
*
* Insert a (symbol-string, value) into the hash table.
* Return an error string, "" means OK.
* It is an 'error' to insert an existing symbol.
*/
char * /* return error string */
hash_insert(handle,string,value)
register struct hash_control * handle;
register char * string;
register char * value;
{
register struct hash_entry * entry;
register char * retval;
retval = "";
if (handle->hash_stat[STAT_USED] > handle->hash_full)
{
retval = hash_grow(handle);
}
if ( ! * retval)
{
entry = hash_ask(handle,string,STAT__WRITE);
if (hash_found)
{
retval = "exists";
}
else
{
entry -> hash_value = value;
entry -> hash_string = string;
handle-> hash_stat[STAT_USED] += 1;
}
}
return(retval);
}
/*
* h a s h _ j a m ( )
*
* Regardless of what was in the symbol table before, after hash_jam()
* the named symbol has the given value. The symbol is either inserted or
* (its value is) relpaced.
* An error message string is returned, "" means OK.
*
* WARNING: this may decide to grow the hashed symbol table.
* To do this, we call hash_grow(), WHICH WILL recursively CALL US.
*
* We report status internally: hash_found is TRUE if we replaced, but
* false if we inserted.
*/
char *
hash_jam(handle,string,value)
register struct hash_control * handle;
register char * string;
register char * value;
{
register char * retval;
register struct hash_entry * entry;
retval = "";
if (handle->hash_stat[STAT_USED] > handle->hash_full)
{
retval = hash_grow(handle);
}
if (! * retval)
{
entry = hash_ask(handle,string,STAT__WRITE);
if ( ! hash_found)
{
entry -> hash_string = string;
handle->hash_stat[STAT_USED] += 1;
}
entry -> hash_value = value;
}
return(retval);
}
/*
* h a s h _ g r o w ( )
*
* Grow a new (bigger) hash table from the old one.
* We choose to double the hash table's size.
* Return a human-scrutible error string: "" if OK.
* Warning! This uses hash_jam(), which had better not recurse
* back here! Hash_jam() conditionally calls us, but we ALWAYS
* call hash_jam()!
* Internal.
*/
static char *
hash_grow(handle) /* make a hash table grow */
struct hash_control * handle;
{
register struct hash_entry * newwall;
register struct hash_entry * newwhere;
struct hash_entry * newtrack;
register struct hash_entry * oldtrack;
register struct hash_entry * oldwhere;
register struct hash_entry * oldwall;
register int temp;
int newsize;
char * string;
char * retval;
#ifdef SUSPECT
int oldused;
#endif
/*
* capture info about old hash table
*/
oldwhere = handle -> hash_where;
oldwall = handle -> hash_wall;
#ifdef SUSPECT
oldused = handle -> hash_stat[STAT_USED];
#endif
/*
* attempt to get enough room for a hash table twice as big
*/
temp = handle->hash_stat[STAT_SIZE];
if (( newwhere = (struct hash_entry *)
xmalloc((long)((temp+temp+1)*sizeof(struct hash_entry)))) != NULL)
/* +1 for wall slot */
{
retval = ""; /* assume success until proven otherwise */
/*
* have enough room: now we do all the work.
* double the size of everything in handle,
* note: hash_mask frob works for 1's & for 2's complement machines
*/
handle->hash_mask = handle->hash_mask + handle->hash_mask + 1;
handle->hash_stat[STAT_SIZE] <<= 1;
newsize = handle->hash_stat[STAT_SIZE];
handle->hash_where = newwhere;
handle->hash_full <<= 1;
handle->hash_sizelog += 1;
handle->hash_stat[STAT_USED] = 0;
handle->hash_wall =
newwall = newwhere + newsize;
/*
* set all those pesky new slots to vacant.
*/
for (newtrack=newwhere; newtrack <= newwall; newtrack++)
{
newtrack -> hash_string = NULL;
}
/*
* we will do a scan of the old table, the hard way, using the
* new control block to re-insert the data into new hash table.
*/
handle -> hash_stat[STAT_USED] = 0; /* inserts will bump it up to correct */
for (oldtrack=oldwhere; oldtrack < oldwall; oldtrack++)
{
if ( ((string=oldtrack->hash_string) != NULL) && string!=DELETED )
{
if ( * (retval = hash_jam(handle,string,oldtrack->hash_value) ) )
{
break;
}
}
}
#ifdef SUSPECT
if ( !*retval && handle->hash_stat[STAT_USED] != oldused)
{
retval = "hash_used";
}
#endif
if (!*retval)
{
/*
* we have a completely faked up control block.
* return the old hash table.
*/
free((char *)oldwhere);
/*
* Here with success. retval is already "".
*/
}
}
else
{
retval = "no room";
}
return(retval);
}
/*
* h a s h _ a p p l y ( )
*
* Use this to scan each entry in symbol table.
* For each symbol, this calls (applys) a nominated function supplying the
* symbol's value (and the symbol's name).
* The idea is you use this to destroy whatever is associted with
* any values in the table BEFORE you destroy the table with hash_die.
* Of course, you can use it for other jobs; whenever you need to
* visit all extant symbols in the table.
*
* We choose to have a call-you-back idea for two reasons:
* asthetic: it is a neater idea to use apply than an explicit loop
* sensible: if we ever had to grow the symbol table (due to insertions)
* then we would lose our place in the table when we re-hashed
* symbols into the new table in a different order.
*
* The order symbols are visited depends entirely on the hashing function.
* Whenever you insert a (symbol, value) you risk expanding the table. If
* you do expand the table, then the hashing function WILL change, so you
* MIGHT get a different order of symbols visited. In other words, if you
* want the same order of visiting symbols as the last time you used
* hash_apply() then you better not have done any hash_insert()s or
* hash_jam()s since the last time you used hash_apply().
*
* In future we may use the value returned by your nominated function.
* One idea is to abort the scan if, after applying the function to a
* certain node, the function returns a certain code.
* To be safe, please make your functions of type char *. If you always
* return NULL, then the scan will complete, visiting every symbol in
* the table exactly once. ALL OTHER RETURNED VALUES have no meaning yet!
* Caveat Actor!
*
* The function you supply should be of the form:
* char * myfunct(string,value)
* char * string; |* the symbol's name *|
* char * value; |* the symbol's value *|
* {
* |* ... *|
* return(NULL);
* }
*
* The returned value of hash_apply() is (char*)NULL. In future it may return
* other values. NULL means "completed scan OK". Other values have no meaning
* yet. (The function has no graceful failures.)
*/
char *
hash_apply(handle,function)
struct hash_control * handle;
char* (*function)();
{
register struct hash_entry * entry;
register struct hash_entry * wall;
wall = handle->hash_wall;
for (entry = handle->hash_where; entry < wall; entry++)
{
if (islive(entry)) /* silly code: tests entry->string twice! */
{
(*function)(entry->hash_string,entry->hash_value);
}
}
return (NULL);
}
/*
* h a s h _ f i n d ( )
*
* Given symbol string, find value (if any).
* Return found value or NULL.
*/
char *
hash_find(handle,string) /* return char* or NULL */
struct hash_control * handle;
char * string;
{
register struct hash_entry * entry;
register char * retval;
entry = hash_ask(handle,string,STAT__READ);
if (hash_found)
{
retval = entry->hash_value;
}
else
{
retval = NULL;
}
return(retval);
}
/*
* h a s h _ a s k ( )
*
* Searches for given symbol string.
* Return the slot where it OUGHT to live. It may be there.
* Return hash_found: TRUE only if symbol is in that slot.
* Access argument is to help keep statistics in control block.
* Internal.
*/
static struct hash_entry * /* string slot, may be empty or deleted */
hash_ask(handle,string,access)
struct hash_control * handle;
char * string;
int access; /* access type */
{
register char *string1; /* JF avoid strcmp calls */
register char * s;
register int c;
register struct hash_entry * slot;
register int collision; /* count collisions */
slot = handle->hash_where + hash_code(handle,string); /* start looking here */
handle->hash_stat[STAT_ACCESS+access] += 1;
collision = 0;
hash_found = FALSE;
while ( ((s = slot->hash_string) != NULL) && s!=DELETED )
{
for(string1=string;;) {
if((c= *s++) == 0) {
if(!*string1)
hash_found = TRUE;
break;
}
if(*string1++!=c)
break;
}
if(hash_found)
break;
collision++;
slot++;
}
/*
* slot: return:
* in use: we found string slot
* at empty:
* at wall: we fell off: wrap round ????
* in table: dig here slot
* at DELETED: dig here slot
*/
if (slot==handle->hash_wall)
{
slot = handle->hash_where; /* now look again */
while( ((s = slot->hash_string) != NULL) && s!=DELETED )
{
for(string1=string;*s;string1++,s++) {
if(*string1!=*s)
break;
}
if(*s==*string1) {
hash_found = TRUE;
break;
}
collision++;
slot++;
}
/*
* slot: return:
* in use: we found it slot
* empty: wall: ERROR IMPOSSIBLE !!!!
* in table: dig here slot
* DELETED:dig here slot
*/
}
/* fprintf(stderr,"hash_ask(%s)->%d(%d)\n",string,hash_code(handle,string),collision); */
handle -> hash_stat[STAT_COLLIDE+access] += collision;
return(slot); /* also return hash_found */
}
/*
* h a s h _ c o d e
*
* Does hashing of symbol string to hash number.
* Internal.
*/
static int
hash_code(handle,string)
struct hash_control * handle;
register char * string;
{
register long h; /* hash code built here */
register long c; /* each character lands here */
register int n; /* Amount to shift h by */
n = (handle->hash_sizelog - 3);
h = 0;
while ((c = *string++) != 0)
{
h += c;
h = (h<<3) + (h>>n) + c;
}
return (h & handle->hash_mask);
}
/*
* Here is a test program to exercise above.
*/
#ifdef TEST
#define TABLES (6) /* number of hash tables to maintain */
/* (at once) in any testing */
#define STATBUFSIZE (12) /* we can have 12 statistics */
int statbuf[STATBUFSIZE]; /* display statistics here */
char answer[100]; /* human farts here */
char * hashtable[TABLES]; /* we test many hash tables at once */
char * h; /* points to curent hash_control */
char ** pp;
char * p;
char * name;
char * value;
int size;
int used;
char command;
int number; /* number 0:TABLES-1 of current hashed */
/* symbol table */
main()
{
char (*applicatee());
char * hash_find();
char * destroy();
char * what();
struct hash_control * hash_new();
char * hash_replace();
int * ip;
number = 0;
h = 0;
printf("type h <RETURN> for help\n");
for(;;)
{
printf("hash_test command: ");
gets(answer);
command = answer[0];
if (isupper(command)) command = tolower(command); /* ecch! */
switch (command)
{
case '#':
printf("old hash table #=%d.\n",number);
whattable();
break;
case '?':
for (pp=hashtable; pp<hashtable+TABLES; pp++)
{
printf("address of hash table #%d control block is %xx\n"
,pp-hashtable,*pp);
}
break;
case 'a':
hash_apply(h,applicatee);
break;
case 'd':
hash_apply(h,destroy);
hash_die(h);
break;
case 'f':
p = hash_find(h,name=what("symbol"));
printf("value of \"%s\" is \"%s\"\n",name,p?p:"NOT-PRESENT");
break;
case 'h':
printf("# show old, select new default hash table number\n");
printf("? display all hashtable control block addresses\n");
printf("a apply a simple display-er to each symbol in table\n");
printf("d die: destroy hashtable\n");
printf("f find value of nominated symbol\n");
printf("h this help\n");
printf("i insert value into symbol\n");
printf("j jam value into symbol\n");
printf("n new hashtable\n");
printf("r replace a value with another\n");
printf("s say what %% of table is used\n");
printf("q exit this program\n");
printf("x delete a symbol from table, report its value\n");
break;
case 'i':
p = hash_insert(h,name=what("symbol"),value=what("value"));
if (*p)
{
printf("symbol=\"%s\" value=\"%s\" error=%s\n",name,value,p);
}
break;
case 'j':
p = hash_jam(h,name=what("symbol"),value=what("value"));
if (*p)
{
printf("symbol=\"%s\" value=\"%s\" error=%s\n",name,value,p);
}
break;
case 'n':
h = hashtable[number] = (char *) hash_new();
break;
case 'q':
exit();
case 'r':
p = hash_replace(h,name=what("symbol"),value=what("value"));
printf("old value was \"%s\"\n",p?p:"{}");
break;
case 's':
hash_say(h,statbuf,STATBUFSIZE);
for (ip=statbuf; ip<statbuf+STATBUFSIZE; ip++)
{
printf("%d ",*ip);
}
printf("\n");
break;
case 'x':
p = hash_delete(h,name=what("symbol"));
printf("old value was \"%s\"\n",p?p:"{}");
break;
default:
printf("I can't understand command \"%c\"\n",command);
break;
}
}
}
char *
what(description)
char * description;
{
char * retval;
char * malloc();
printf(" %s : ",description);
gets(answer);
/* will one day clean up answer here */
retval = malloc(strlen(answer)+1);
if (!retval)
{
error("room");
}
(void)strcpy(retval,answer);
return(retval);
}
char *
destroy(string,value)
char * string;
char * value;
{
free(string);
free(value);
return(NULL);
}
char *
applicatee(string,value)
char * string;
char * value;
{
printf("%.20s-%.20s\n",string,value);
return(NULL);
}
whattable() /* determine number: what hash table to use */
/* also determine h: points to hash_control */
{
for (;;)
{
printf(" what hash table (%d:%d) ? ",0,TABLES-1);
gets(answer);
sscanf(answer,"%d",&number);
if (number>=0 && number<TABLES)
{
h = hashtable[number];
if (!h)
{
printf("warning: current hash-table-#%d. has no hash-control\n",number);
}
return;
}
else
{
printf("invalid hash table number: %d\n",number);
}
}
}
#endif /* #ifdef TEST */
/* end: hash.c */
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