6594d6b9c2
table entries, table allocation and control structure are larger now, but collisions are reduced and string compares even further reduced. Dump lots more statistics, especially hash code data, for --statistics. Dump statistics even in error cases. Details in ChangeLog.
1018 lines
29 KiB
C
1018 lines
29 KiB
C
/* hash.c - hash table lookup strings -
|
||
Copyright (C) 1987, 1990, 1991, 1992 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 2, 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
|
||
|
||
/*
|
||
* BUGS, GRIPES, APOLOGIA etc.
|
||
*
|
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* A typical user doesn't need ALL this: I intend to make a library out
|
||
* of it one day - Dean Elsner.
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||
* Also, I want to change the definition of a symbol to (address,length)
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* so I can put arbitrary binary in the names stored. [see hsh.c for that]
|
||
*
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* This slime is common coupled inside the module. Com-coupling (and other
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* vandalism) was done to speed running time. The interfaces at the
|
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* module's edges are adequately clean.
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*
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* There is no way to (a) run a test script through this heap and (b)
|
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* compare results with previous scripts, to see if we have broken any
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* code. Use GNU (f)utilities to do this. A few commands assist test.
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* The testing is awkward: it tries to be both batch & interactive.
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* For now, interactive rules!
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*/
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/*
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* The idea is to implement a symbol table. A test jig is here.
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* Symbols are arbitrary strings; they can't contain '\0'.
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* [See hsh.c for a more general symbol flavour.]
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* Each symbol is associated with a char*, which can point to anything
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* you want, allowing an arbitrary property list for each symbol.
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*
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* The basic operations are:
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*
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* new creates symbol table, returns handle
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* find (symbol) returns char*
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* insert (symbol,char*) error if symbol already in table
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* delete (symbol) returns char* if symbol was in table
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* apply so you can delete all symbols before die()
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* die destroy symbol table (free up memory)
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*
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* Supplementary functions include:
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*
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* say how big? what % full?
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* replace (symbol,newval) report previous value
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* jam (symbol,value) assert symbol:=value
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*
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* You, the caller, have control over errors: this just reports them.
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*
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* This package requires malloc(), free().
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* Malloc(size) returns NULL or address of char[size].
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* Free(address) frees same.
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*/
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/*
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* The code and its structures are re-enterent.
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*
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* Before you do anything else, you must call hash_new() which will
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* return the address of a hash-table-control-block. You then use
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* this address as a handle of the symbol table by passing it to all
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* the other hash_...() functions. The only approved way to recover
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* the memory used by the symbol table is to call hash_die() with the
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* handle of the symbol table.
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*
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* Before you call hash_die() you normally delete anything pointed to
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* by individual symbols. After hash_die() you can't use that symbol
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* table again.
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*
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* The char* you associate with a symbol may not be NULL (0) because
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* NULL is returned whenever a symbol is not in the table. Any other
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* value is OK, except DELETED, #defined below.
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*
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* When you supply a symbol string for insertion, YOU MUST PRESERVE THE
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* STRING until that symbol is deleted from the table. The reason is that
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* only the address you supply, NOT the symbol string itself, is stored
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* in the symbol table.
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*
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* You may delete and add symbols arbitrarily.
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* Any or all symbols may have the same 'value' (char *). In fact, these
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* routines don't do anything with your symbol values.
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*
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* You have no right to know where the symbol:char* mapping is stored,
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* because it moves around in memory; also because we may change how it
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* works and we don't want to break your code do we? However the handle
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* (address of struct hash_control) is never changed in
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* the life of the symbol table.
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*
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* What you CAN find out about a symbol table is:
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* how many slots are in the hash table?
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* how many slots are filled with symbols?
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* (total hashes,collisions) for (reads,writes) (*)
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* All of the above values vary in time.
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* (*) some of these numbers will not be meaningful if we change the
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* internals. */
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/*
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* I N T E R N A L
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*
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* Hash table is an array of hash_entries; each entry is a pointer to a
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* a string and a user-supplied value 1 char* wide.
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*
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* The array always has 2 ** n elements, n>0, n integer.
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* There is also a 'wall' entry after the array, which is always empty
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* and acts as a sentinel to stop running off the end of the array.
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* When the array gets too full, we create a new array twice as large
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* and re-hash the symbols into the new array, then forget the old array.
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* (Of course, we copy the values into the new array before we junk the
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* old array!)
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*
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*/
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#include <stdio.h>
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#ifndef FALSE
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#define FALSE (0)
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#define TRUE (!FALSE)
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#endif /* no FALSE yet */
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#include <ctype.h>
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#define min(a, b) ((a) < (b) ? (a) : (b))
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#include "as.h"
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#define error as_fatal
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static char _deleted_[1];
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#define DELETED ((PTR)_deleted_) /* guarenteed unique address */
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#define START_POWER (10) /* power of two: size of new hash table */
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/* TRUE if a symbol is in entry @ ptr. */
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#define islive(ptr) (ptr->hash_string && ptr->hash_string!=DELETED)
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enum stat_enum {
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/* Number of slots in hash table. The wall does not count here.
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We expect this is always a power of 2. */
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STAT_SIZE = 0,
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/* Number of hash_ask calls. */
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STAT_ACCESS,
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STAT_ACCESS_w,
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/* Number of collisions (total). This may exceed STAT_ACCESS if we
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have lots of collisions/access. */
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STAT_COLLIDE,
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STAT_COLLIDE_w,
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/* Slots used right now. */
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STAT_USED,
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/* How many string compares? */
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STAT_STRCMP,
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STAT_STRCMP_w,
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/* Size of statistics block... this must be last. */
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STATLENGTH
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};
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#define STAT__READ (0) /* reading */
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#define STAT__WRITE (1) /* writing */
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/* When we grow a hash table, by what power of two do we increase it? */
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#define GROW_FACTOR 1
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/* When should we grow it? */
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#define FULL_VALUE(N) ((N) / 4)
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/* #define SUSPECT to do runtime checks */
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/* #define TEST to be a test jig for hash...() */
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#ifdef TEST
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/* TEST: use smaller hash table */
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#undef START_POWER
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#define START_POWER (3)
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#undef START_SIZE
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#define START_SIZE (8)
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#undef START_FULL
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#define START_FULL (4)
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#endif
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struct hash_control {
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struct hash_entry *hash_where;/* address of hash table */
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int hash_sizelog; /* Log of ( hash_mask + 1 ) */
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int hash_mask; /* masks a hash into index into table */
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int hash_full; /* when hash_stat[STAT_USED] exceeds this, */
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/* grow table */
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struct hash_entry *hash_wall; /* point just after last (usable) entry */
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/* here we have some statistics */
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int hash_stat[STATLENGTH]; /* lies & statistics */
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};
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/*------------------ plan ---------------------------------- i = internal
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struct hash_control * c;
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struct hash_entry * e; i
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int b[z]; buffer for statistics
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z size of b
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char * s; symbol string (address) [ key ]
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char * v; value string (address) [datum]
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boolean f; TRUE if we found s in hash table i
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char * t; error string; 0 means OK
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int a; access type [0...n) i
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c=hash_new () create new hash_control
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hash_die (c) destroy hash_control (and hash table)
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table should be empty.
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doesn't check if table is empty.
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c has no meaning after this.
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hash_say (c,b,z) report statistics of hash_control.
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also report number of available statistics.
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v=hash_delete (c,s) delete symbol, return old value if any.
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ask() NULL means no old value.
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f
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v=hash_replace (c,s,v) replace old value of s with v.
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ask() NULL means no old value: no table change.
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f
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t=hash_insert (c,s,v) insert (s,v) in c.
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ask() return error string.
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f it is an error to insert if s is already
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in table.
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if any error, c is unchanged.
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|
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t=hash_jam (c,s,v) assert that new value of s will be v. i
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ask() it may decide to GROW the table. i
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f i
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grow() i
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t=hash_grow (c) grow the hash table. i
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jam() will invoke JAM. i
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?=hash_apply (c,y) apply y() to every symbol in c.
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y evtries visited in 'unspecified' order.
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v=hash_find (c,s) return value of s, or NULL if s not in c.
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||
ask()
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f
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|
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f,e=hash_ask() (c,s,a) return slot where s SHOULD live. i
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code() maintain collision stats in c. i
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.=hash_code (c,s) compute hash-code for s, i
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from parameters of c. i
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*/
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/* Returned by hash_ask() to stop extra testing. hash_ask() wants to
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return both a slot and a status. This is the status. TRUE: found
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symbol FALSE: absent: empty or deleted slot Also returned by
|
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hash_jam(). TRUE: we replaced a value FALSE: we inserted a value. */
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||
static char hash_found;
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||
static struct hash_entry *hash_ask PARAMS ((struct hash_control *,
|
||
const char *, int));
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||
static int hash_code PARAMS ((struct hash_control *, const char *));
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||
static const char *hash_grow PARAMS ((struct hash_control *));
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|
||
/* Create a new hash table. Return NULL if failed; otherwise return handle
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(address of struct hash). */
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struct hash_control *
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hash_new ()
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{
|
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struct hash_control *retval;
|
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struct hash_entry *room; /* points to hash table */
|
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struct hash_entry *wall;
|
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struct hash_entry *entry;
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int *ip; /* scan stats block of struct hash_control */
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int *nd; /* limit of stats block */
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|
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room = (struct hash_entry *) xmalloc (sizeof (struct hash_entry)
|
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/* +1 for the wall entry */
|
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* ((1 << START_POWER) + 1));
|
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retval = (struct hash_control *) xmalloc (sizeof (struct hash_control));
|
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|
||
nd = retval->hash_stat + STATLENGTH;
|
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for (ip = retval->hash_stat; ip < nd; ip++)
|
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*ip = 0;
|
||
|
||
retval->hash_stat[STAT_SIZE] = 1 << START_POWER;
|
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retval->hash_mask = (1 << START_POWER) - 1;
|
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retval->hash_sizelog = START_POWER;
|
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/* works for 1's compl ok */
|
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retval->hash_where = room;
|
||
retval->hash_wall =
|
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wall = room + (1 << START_POWER);
|
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retval->hash_full = FULL_VALUE (1 << START_POWER);
|
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for (entry = room; entry <= wall; entry++)
|
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entry->hash_string = NULL;
|
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return retval;
|
||
}
|
||
|
||
/*
|
||
* h a s h _ d i e ( )
|
||
*
|
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* 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);
|
||
}
|
||
|
||
#ifdef TEST
|
||
/*
|
||
* 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.
|
||
*/
|
||
static void
|
||
hash_say (handle, buffer, bufsiz)
|
||
struct hash_control *handle;
|
||
int buffer[ /*bufsiz*/ ];
|
||
int bufsiz;
|
||
{
|
||
int *nd; /* limit of statistics block */
|
||
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;
|
||
}
|
||
}
|
||
}
|
||
#endif
|
||
|
||
/*
|
||
* 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.
|
||
*
|
||
*/
|
||
PTR /* NULL if string not in table, else */
|
||
/* returns value of deleted symbol */
|
||
hash_delete (handle, string)
|
||
struct hash_control *handle;
|
||
const char *string;
|
||
{
|
||
PTR retval;
|
||
struct hash_entry *entry;
|
||
|
||
entry = hash_ask (handle, string, STAT__WRITE);
|
||
if (hash_found)
|
||
{
|
||
retval = entry->hash_value;
|
||
entry->hash_string = DELETED;
|
||
handle->hash_stat[STAT_USED] -= 1;
|
||
#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.
|
||
*/
|
||
PTR
|
||
hash_replace (handle, string, value)
|
||
struct hash_control *handle;
|
||
const char *string;
|
||
PTR value;
|
||
{
|
||
struct hash_entry *entry;
|
||
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, 0 means OK.
|
||
* It is an 'error' to insert an existing symbol.
|
||
*/
|
||
|
||
const char * /* return error string */
|
||
hash_insert (handle, string, value)
|
||
struct hash_control *handle;
|
||
const char *string;
|
||
PTR value;
|
||
{
|
||
struct hash_entry *entry;
|
||
const char *retval;
|
||
|
||
retval = 0;
|
||
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) replaced.
|
||
* An error message string is returned, 0 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.
|
||
*/
|
||
const char *
|
||
hash_jam (handle, string, value)
|
||
struct hash_control *handle;
|
||
const char *string;
|
||
PTR value;
|
||
{
|
||
const char *retval;
|
||
struct hash_entry *entry;
|
||
|
||
retval = 0;
|
||
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: 0 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 const char *
|
||
hash_grow (handle) /* make a hash table grow */
|
||
struct hash_control *handle;
|
||
{
|
||
struct hash_entry *newwall;
|
||
struct hash_entry *newwhere;
|
||
struct hash_entry *newtrack;
|
||
struct hash_entry *oldtrack;
|
||
struct hash_entry *oldwhere;
|
||
struct hash_entry *oldwall;
|
||
int temp;
|
||
int newsize;
|
||
const char *string;
|
||
const 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];
|
||
newwhere = ((struct hash_entry *)
|
||
xmalloc ((unsigned long) ((temp << GROW_FACTOR + 1)
|
||
/* +1 for wall slot */
|
||
* sizeof (struct hash_entry))));
|
||
if (newwhere == NULL)
|
||
return "no_room";
|
||
|
||
/*
|
||
* have enough room: now we do all the work.
|
||
* double the size of everything in handle.
|
||
*/
|
||
handle->hash_mask = ((handle->hash_mask + 1) << GROW_FACTOR) - 1;
|
||
handle->hash_stat[STAT_SIZE] <<= GROW_FACTOR;
|
||
newsize = handle->hash_stat[STAT_SIZE];
|
||
handle->hash_where = newwhere;
|
||
handle->hash_full <<= GROW_FACTOR;
|
||
handle->hash_sizelog += GROW_FACTOR;
|
||
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;
|
||
for (oldtrack = oldwhere; oldtrack < oldwall; oldtrack++)
|
||
if (((string = oldtrack->hash_string) != NULL) && string != DELETED)
|
||
if ((retval = hash_jam (handle, string, oldtrack->hash_value)))
|
||
return retval;
|
||
|
||
#ifdef SUSPECT
|
||
if (handle->hash_stat[STAT_USED] != oldused)
|
||
return "hash_used";
|
||
#endif
|
||
|
||
/* We have a completely faked up control block.
|
||
Return the old hash table. */
|
||
free ((char *) oldwhere);
|
||
|
||
return 0;
|
||
}
|
||
|
||
#ifdef TEST
|
||
/*
|
||
* 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.
|
||
*
|
||
* The function you supply should be of the form:
|
||
* void myfunct(string,value)
|
||
* char * string; |* the symbol's name *|
|
||
* char * value; |* the symbol's value *|
|
||
* {
|
||
* |* ... *|
|
||
* }
|
||
*
|
||
*/
|
||
void
|
||
hash_apply (handle, function)
|
||
struct hash_control *handle;
|
||
void (*function) ();
|
||
{
|
||
struct hash_entry *entry;
|
||
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);
|
||
}
|
||
}
|
||
}
|
||
#endif
|
||
|
||
/*
|
||
* h a s h _ f i n d ( )
|
||
*
|
||
* Given symbol string, find value (if any).
|
||
* Return found value or NULL.
|
||
*/
|
||
PTR
|
||
hash_find (handle, string)
|
||
struct hash_control *handle;
|
||
const char *string;
|
||
{
|
||
struct hash_entry *entry;
|
||
|
||
entry = hash_ask (handle, string, STAT__READ);
|
||
if (hash_found)
|
||
return entry->hash_value;
|
||
else
|
||
return NULL;
|
||
}
|
||
|
||
/*
|
||
* 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_type)
|
||
struct hash_control *handle;
|
||
const char *string;
|
||
int access_type;
|
||
{
|
||
const char *s;
|
||
struct hash_entry *slot;
|
||
int collision; /* count collisions */
|
||
int strcmps;
|
||
int hcode;
|
||
|
||
/* start looking here */
|
||
hcode = hash_code (handle, string);
|
||
slot = handle->hash_where + (hcode & handle->hash_mask);
|
||
|
||
handle->hash_stat[STAT_ACCESS + access_type] += 1;
|
||
collision = strcmps = 0;
|
||
hash_found = FALSE;
|
||
while (((s = slot->hash_string) != NULL) && s != DELETED)
|
||
{
|
||
if (string == s)
|
||
{
|
||
hash_found = TRUE;
|
||
break;
|
||
}
|
||
if (slot->h == hcode)
|
||
{
|
||
if (!strcmp (string, s))
|
||
{
|
||
hash_found = TRUE;
|
||
break;
|
||
}
|
||
strcmps++;
|
||
}
|
||
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)
|
||
{
|
||
if (string == s)
|
||
{
|
||
hash_found = TRUE;
|
||
break;
|
||
}
|
||
if (slot->h == hcode)
|
||
{
|
||
if (!strcmp (string, s))
|
||
{
|
||
hash_found = TRUE;
|
||
break;
|
||
}
|
||
strcmps++;
|
||
}
|
||
collision++;
|
||
slot++;
|
||
}
|
||
/*
|
||
* slot: return:
|
||
* in use: we found it slot
|
||
* empty: wall: ERROR IMPOSSIBLE !!!!
|
||
* in table: dig here slot
|
||
* DELETED:dig here slot
|
||
*/
|
||
}
|
||
handle->hash_stat[STAT_COLLIDE + access_type] += collision;
|
||
handle->hash_stat[STAT_STRCMP + access_type] += strcmps;
|
||
if (!hash_found)
|
||
slot->h = hcode;
|
||
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;
|
||
const char *string;
|
||
{
|
||
#if 1 /* There seems to be some interesting property of this function
|
||
that prevents the bfd version below from being an adequate
|
||
substitute. @@ Figure out what this property is! */
|
||
long h; /* hash code built here */
|
||
long c; /* each character lands here */
|
||
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;
|
||
#else
|
||
/* from bfd */
|
||
unsigned long h = 0;
|
||
unsigned int len = 0;
|
||
unsigned int c;
|
||
|
||
while ((c = *string++) != 0)
|
||
{
|
||
h += c + (c << 17);
|
||
h ^= h >> 2;
|
||
++len;
|
||
}
|
||
h += len + (len << 17);
|
||
h ^= h >> 2;
|
||
return h;
|
||
#endif
|
||
}
|
||
|
||
void
|
||
hash_print_statistics (file, name, h)
|
||
FILE *file;
|
||
const char *name;
|
||
struct hash_control *h;
|
||
{
|
||
unsigned long sz, used, pct;
|
||
|
||
if (h == 0)
|
||
return;
|
||
|
||
sz = h->hash_stat[STAT_SIZE];
|
||
used = h->hash_stat[STAT_USED];
|
||
pct = (used * 100 + sz / 2) / sz;
|
||
|
||
fprintf (file, "%s hash statistics:\n\t%d/%d slots used (%d%%)\n",
|
||
name, used, sz, pct);
|
||
|
||
#define P(name, off) \
|
||
fprintf (file, "\t%-16s %6dr + %6dw = %7d\n", name, \
|
||
h->hash_stat[off+STAT__READ], \
|
||
h->hash_stat[off+STAT__WRITE], \
|
||
h->hash_stat[off+STAT__READ] + h->hash_stat[off+STAT__WRITE])
|
||
|
||
P ("accesses:", STAT_ACCESS);
|
||
P ("collisions:", STAT_COLLIDE);
|
||
P ("string compares:", STAT_STRCMP);
|
||
|
||
#undef P
|
||
}
|
||
|
||
/*
|
||
* 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 ()
|
||
{
|
||
void applicatee ();
|
||
void destroy ();
|
||
char *what ();
|
||
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 (EXIT_SUCCESS);
|
||
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);
|
||
}
|
||
|
||
void
|
||
destroy (string, value)
|
||
char *string;
|
||
char *value;
|
||
{
|
||
free (string);
|
||
free (value);
|
||
}
|
||
|
||
|
||
void
|
||
applicatee (string, value)
|
||
char *string;
|
||
char *value;
|
||
{
|
||
printf ("%.20s-%.20s\n", string, value);
|
||
}
|
||
|
||
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 of hash.c */
|