calc/quickhash.c

/*
 * quickhash - quickly hash a calc value using a 32-bit FNV-0 hash
 *
 * WARNING: General use of FNV-0 hash is not recommended.  Calc uses FNV-0
 *          for a specific You should use FNV-1a hash instead.  See:
 *
 *      http://www.isthe.com/chongo/tech/comp/fnv/index.html
 *
 * Copyright (C) 1999-2007,2014,2021-2023  Landon Curt Noll
 *
 * Calc is open software; you can redistribute it and/or modify it under
 * the terms of the version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * Calc 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 Lesser General
 * Public License for more details.
 *
 * A copy of version 2.1 of the GNU Lesser General Public License is
 * distributed with calc under the filename COPYING-LGPL.  You should have
 * received a copy with calc; if not, write to Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Under source code control:   1995/03/04 11:34:23
 * File existed as early as:    1995
 *
 * chongo <was here> /\oo/\     http://www.isthe.com/chongo/
 * Share and enjoy!  :-)        http://www.isthe.com/chongo/tech/comp/calc/
 */

/*
 * NOTE: This file does not contain a hash interface.  It is used by
 *       associative arrays and other internal processes.
 */


#include "value.h"
#include "zrand.h"
#include "zrandom.h"


#include "errtbl.h"
#include "banned.h"     /* include after system header <> includes */


/*
 * forward declarations
 */
S_FUNC QCKHASH assochash(ASSOC *ap, QCKHASH val);
S_FUNC QCKHASH listhash(LIST *lp, QCKHASH val);
S_FUNC QCKHASH mathash(MATRIX *m, QCKHASH val);
S_FUNC QCKHASH objhash(OBJECT *op, QCKHASH val);
S_FUNC QCKHASH randhash(RAND *r, QCKHASH val);
S_FUNC QCKHASH randomhash(RANDOM *state, QCKHASH val);
S_FUNC QCKHASH config_hash(CONFIG *cfg, QCKHASH val);
S_FUNC QCKHASH fnv_strhash(char *ch, QCKHASH val);
S_FUNC QCKHASH fnv_STRhash(STRING *str, QCKHASH val);
S_FUNC QCKHASH fnv_fullhash(FULL *v, LEN len, QCKHASH val);
S_FUNC QCKHASH fnv_zhash(ZVALUE z, QCKHASH val);
S_FUNC QCKHASH hash_hash(HASH *hash, QCKHASH val);
S_FUNC QCKHASH blk_hash(BLOCK *blk, QCKHASH val);


/*
 * quasi_fnv - quasi Fowler/Noll/Vo-0 32 bit hash
 *
 * NOTE: General use of FNV-0 hash
 *
 * The basis of this hash algorithm was taken from an idea sent
 * as reviewer comments to the IEEE POSIX P1003.2 committee by:
 *
 *      Phong Vo (http://www.research.att.com/info/kpv/)
 *      Glenn Fowler (http://www.research.att.com/~gsf/)
 *
 * In a subsequent ballot round:
 *
 *      Landon Curt Noll (http://www.isthe.com/chongo/)
 *
 * improved on their algorithm.  Some people tried this hash
 * and found that it worked rather well.  In an Email message
 * to Landon, they named it ``Fowler/Noll/Vo'' or the FNV hash.
 *
 * FNV hashes are designed to be fast while maintaining a low
 * collision rate. The FNV speed allows one to quickly hash lots
 * of data while maintaining a reasonable collision rate.  See:
 *
 *      http://www.isthe.com/chongo/tech/comp/fnv/index.html
 *
 * for more details as well as other forms of the FNV hash.
 *
 * given:
 *      x       the value to hash (must not be longer than 32 bits)
 *      val     previous QCKHASH value
 *
 * returns:
 *      the next 32 bit QCKHASH
 *
 * Example:
 *      QCKHASH val;
 *      int x;
 *
 *      quasi_fnv(x, val);
 *
 * NOTE: The (x) argument may be an expression such as something with
 *       a ++ or --.  The macro must only use (x) once.
 *
 * NOTE: The (val) argument just be a lvalue / something to which
 *       a value can be assigned.
 *
 * The careful observer will note that (x) need not be a simple
 * octet.  This is not a bug, but a feature.  The FNV hash was
 * designed to operate on octets, not abstract objects such
 * as associations, file descriptors and PRNG states.
 * You will also notice that we sometimes add values directly
 * to the (val) hash state.  This is a simulation of hashing
 * a variable type.
 *
 * The 32-bit FNV-0 hash does a very good job in producing
 * a 32 bit hash arrays of octets in a short amount of time.
 * It is not bad for hashing calc data as well.  So doing a
 * quick and dirty job of hashing on a part of a calc value
 * is all that calc really needs.
 *
 * The core of the of the FNV hash has been adopted as the calc
 * quick hash with the provision that it operates on 32 bit
 * objects instead of octets.  For calc's internal purposes,
 * this is sufficient.  For general FNV hashing, this is not
 * recommended.
 *
 * It has been observed that gcc, when using -O, -O2, -O3 or
 * better on an AMD or AMD-like processor (such as i686) will
 * produce slightly faster code when using the shift/add
 * expression than when performing a multiply with a constant.
 */
#if defined(NO_HASH_CPU_OPTIMIZATION)
#define quasi_fnv(x,val) \
    ((val) = (((QCKHASH)(val)*(QCKHASH)16777619) ^ ((QCKHASH)(x))))
#else
#define quasi_fnv(x,val) ( \
    ((val) += (((QCKHASH)(val)<<1) + ((QCKHASH)(val)<<4) + \
               ((QCKHASH)(val)<<7) + ((QCKHASH)(val)<<8) + \
               ((QCKHASH)(val)<<24))), \
    ((val) ^= (QCKHASH)(x)) \
)
#endif


/*
 * fnv_qhash - compute the next 32-bit FNV-0 hash given a NUMBER
 *
 * given:
 *      q       pointer to a NUMBER
 *      val     previous QCKHASH value
 *
 * returns:
 *      the next 32 bit QCKHASH
 */
#define fnv_qhash(q,val) \
  (qisint(q) ? fnv_zhash((q)->num, (val)) : \
   fnv_zhash((q)->num, fnv_zhash((q)->den, (val))))


/*
 * fnv_chash - compute the next 32-bit FNV-0 hash given a COMPLEX
 *
 * given:
 *      c       pointer to a COMPLEX
 *      val     previous QCKHASH value
 *
 * returns:
 *      the next 32 bit QCKHASH
 */
#define fnv_chash(c,val) \
  (cisreal(c) ? fnv_qhash((c)->real, (val)) : \
   fnv_qhash((c)->real, fnv_qhash((c)->imag, (val))))


/*
 * hashvalue - calculate a hash value for a value.
 *
 * The hash does not have to be a perfect one, it is only used for
 * making associations faster.
 *
 * given:
 *      vp      pointer to a VALUE
 *      val     previous QCKHASH value
 *
 * returns:
 *      next QCKHASH value
 */
QCKHASH
hashvalue(VALUE *vp, QCKHASH val)
{
        switch (vp->v_type) {
        case V_INT:
                val += V_NUM;
                return quasi_fnv(vp->v_int, val);
        case V_NUM:
                return fnv_qhash(vp->v_num, val);
        case V_COM:
                return fnv_chash(vp->v_com, val);
        case V_STR:
                return fnv_STRhash(vp->v_str, val);
        case V_NULL:
                return val;
        case V_OBJ:
                return objhash(vp->v_obj, val);
        case V_LIST:
                return listhash(vp->v_list, val);
        case V_ASSOC:
                return assochash(vp->v_assoc, val);
        case V_MAT:
                return mathash(vp->v_mat, val);
        case V_FILE:
                val += V_FILE;
                return quasi_fnv(vp->v_file, val);
        case V_RAND:
                return randhash(vp->v_rand, val);
        case V_RANDOM:
                return randomhash(vp->v_random, val);
        case V_CONFIG:
                return config_hash(vp->v_config, val);
        case V_HASH:
                return hash_hash(vp->v_hash, val);
        case V_BLOCK:
                return blk_hash(vp->v_block, val);
        case V_OCTET:
                val += V_OCTET;
                return quasi_fnv((int)*vp->v_octet, val);
        case V_NBLOCK:
                return blk_hash(vp->v_nblock->blk, val);
        default:
                math_error("Hashing unknown value");
                not_reached();
        }
        return (QCKHASH)0;
}


/*
 * Return a trivial hash value for an association.
 */
S_FUNC QCKHASH
assochash(ASSOC *ap, QCKHASH val)
{
        /*
         * XXX - maybe we should hash the first few and last few values???
         *       Perhaps we should hash associations in a different but
         *       fast way?
         */
        val += V_ASSOC;
        return quasi_fnv(ap->a_count, val);
}


/*
 * Return a trivial hash value for a list.
 */
S_FUNC QCKHASH
listhash(LIST *lp, QCKHASH val)
{
        /*
         * hash small lists
         */
        switch (lp->l_count) {
        case 0:
                /* empty list hashes to just V_LIST */
                return V_LIST+val;
        case 1:
                /* single element list hashes just that element */
                return hashvalue(&lp->l_first->e_value, V_LIST+val);
        }

        /*
         * multi element list hashes the first and last elements
         */
        return hashvalue(&lp->l_first->e_value,
                         hashvalue(&lp->l_last->e_value, V_LIST+val));
}


/*
 * Return a trivial hash value for a matrix.
 */
S_FUNC QCKHASH
mathash(MATRIX *m, QCKHASH val)
{
        long skip;
        long i;
        VALUE *vp;

        /*
         * hash size parts of the matrix
         */
        val += V_MAT;
        quasi_fnv(m->m_dim, val);
        quasi_fnv(m->m_size, val);

        /*
         * hash the matrix index bounds
         */
        for (i = m->m_dim - 1; i >= 0; i--) {
                quasi_fnv(m->m_min[i], val);
                quasi_fnv(m->m_max[i], val);
        }

        /*
         * hash the first 16 elements
         */
        vp = m->m_table;
        for (i = 0; ((i < m->m_size) && (i < 16)); i++) {
                val = hashvalue(vp++, val);
        }

        /*
         * hash 10 more elements if they exist
         */
        i = 16;
        if (i < m->m_size) {
                vp = (VALUE *)&m->m_table[i];
                skip = (m->m_size / 11) + 1;
                while (i < m->m_size) {
                        val = hashvalue(vp, val);
                        i += skip;
                        vp += skip;
                }
        }
        return val;
}


/*
 * Return a trivial hash value for an object.
 */
S_FUNC QCKHASH
objhash(OBJECT *op, QCKHASH val)
{
        int i;

        quasi_fnv(op->o_actions->oa_index, val);

        i = op->o_actions->oa_count;
        while (--i >= 0)
                val = hashvalue(&op->o_table[i], val);
        return val;
}


/*
 * randhash - return a trivial hash for an s100 state
 *
 * given:
 *      state - state to hash
 *
 * returns:
 *      trivial hash integer
 */
S_FUNC QCKHASH
randhash(RAND *r, QCKHASH val)
{
        /*
         * hash the RAND state
         */
        if (!r->seeded) {
                /* unseeded state hashes to V_RAND */
                return V_RAND+val;
        } else {
                /* hash control values */
                val += V_RAND;
                quasi_fnv(r->j, val);
                quasi_fnv(r->k, val);
                quasi_fnv(r->bits, val);
                quasi_fnv(r->need_to_skip, val);

                /* hash the state arrays */
                return fnv_fullhash(&r->buffer[0], SLEN+SCNT+SHUFLEN, val);
        }
}


/*
 * randomhash - return a trivial hash for a Blum state
 *
 * given:
 *      state - state to hash
 *
 * returns:
 *      trivial hash integer
 */
S_FUNC QCKHASH
randomhash(RANDOM *state, QCKHASH val)
{
        /*
         * unseeded RANDOM state hashes to V_RANDOM
         */
        if (!state->seeded) {
                return V_RANDOM+val;
        }

        /*
         * hash a seeded RANDOM state
         */
        val += V_RANDOM;
        quasi_fnv(state->buffer+state->bits, val);
        if (state->r.v != NULL) {
                val = fnv_zhash(state->r, val);
        }
        if (state->n.v != NULL) {
                val = fnv_zhash(state->n, val);
        }
        return val;
}


/*
 * config_hash - return a trivial hash for a configuration state
 */
S_FUNC QCKHASH
config_hash(CONFIG *cfg, QCKHASH val)
{
        USB32 value;            /* value to hash from hash elements */

        /*
         * build up a scalar value
         *
         * We will rotate a value left 5 bits and xor in each scalar element
         */
        value = cfg->outmode;
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->outmode);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->outmode2);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->outdigits);
        /* epsilon is handled out of order */
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->epsilonprec);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->traceflags);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->maxprint);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->mul2);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->sq2);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->pow2);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->redc2);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->tilde_ok);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->tilde_space);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->tab_ok);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->quomod);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->quo);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->mod);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->sqrt);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->appr);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->cfappr);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->cfsim);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->outround);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->round);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->triground);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->leadzero);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->fullzero);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->maxscancount);
        /* prompt1 is handled out of order */
        /* prompt2 is handled out of order */
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->blkmaxprint);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->blkverbose);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->blkbase);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->blkfmt);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->calc_debug);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->resource_debug);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->user_debug);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->verbose_quit);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->ctrl_d);
        /* program is handled out of order */
        /* basename is handled out of order */
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->windows);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->cygwin);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->compile_custom);
        if (cfg->allow_custom != NULL && *(cfg->allow_custom)) {
                value = (((value>>5) | (value<<27)) ^ (USB32)true);
        } else {
                value = (((value>>5) | (value<<27)) ^ (USB32)false);
        }
        /* version is handled out of order */

        /*
         * hash the built up scalar
         */
        val += V_CONFIG;
        quasi_fnv(value, val);

        /*
         * hash the strings and pointers if possible
         */
        if (cfg->prompt1) {
                val = fnv_strhash(cfg->prompt1, val);
        }
        if (cfg->prompt2) {
                val = fnv_strhash(cfg->prompt2, val);
        }
        if (cfg->program) {
                val = fnv_strhash(cfg->program, val);
        }
        if (cfg->base_name) {
                val = fnv_strhash(cfg->base_name, val);
        }
        if (cfg->version) {
                val = fnv_strhash(cfg->version, val);
        }
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->baseb);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->redecl_warn);
        value = (((value>>5) | (value<<27)) ^ (USB32)cfg->dupvar_warn);

        /*
         * hash the epsilon if possible
         */
        if (cfg->epsilon) {
                val = fnv_qhash(cfg->epsilon, val);
        }
        return val;
}


/*
 * fnv_strhash - Fowler/Noll/Vo 32 bit hash of a null-terminated string
 *
 * given:
 *      ch      the start of the string to hash
 *      val     initial hash value
 *
 * returns:
 *      a 32 bit QCKHASH value
 */
S_FUNC QCKHASH
fnv_strhash(char *ch, QCKHASH val)
{
        /*
         * hash each character in the string
         */
        while (*ch) {
                quasi_fnv(*ch++, val);
        }
        return val;
}

/*
 * fnv_STRhash - Fowler/Noll/Vo 32 bit hash of a STRING
 *
 * given:
 *      str     the string to hash
 *      val     initial hash value
 *
 * returns:
 *      a 32 bit QCKHASH value
 */
S_FUNC QCKHASH
fnv_STRhash(STRING *str, QCKHASH val)
{
        char *ch;
        long n;

        ch = str->s_str;
        n = str->s_len;

        /*
         * hash each character in the string
         */
        while (n-- > 0) {
                quasi_fnv(*ch++, val);
        }
        return val;
}


/*
 * fnv_fullhash - Fowler/Noll/Vo 32 bit hash of an array of HALFs
 *
 * given:
 *      v       an array of FULLs
 *      len     length of buffer FULLs
 *      val     initial hash value
 *
 * returns:
 *      a 32 bit QCKHASH value
 */
S_FUNC QCKHASH
fnv_fullhash(FULL *v, LEN len, QCKHASH val)
{
        /*
         * hash each character in the string
         */
        while (len-- > 0) {
                quasi_fnv(*v++, val);
        }
        return val;
}


/*
 * fnv_zhash - Fowler/Noll/Vo 32 bit hash of ZVALUE
 *
 * given:
 *      z       a ZVALUE
 *      val     initial hash value
 *
 * returns:
 *      a 32 bit QCKHASH value
 */
S_FUNC QCKHASH
fnv_zhash(ZVALUE z, QCKHASH val)
{
        LEN n;
        HALF *hp;
#if BASEB == 16
        FULL f;
#endif

        /*
         * hash the sign
         */
        val += V_NUM;
        quasi_fnv(z.sign, val);

        n = z.len;
        hp = z.v;

#if BASEB == 16
        while (n > 1) {
                f = (FULL) *hp++;
                f |= (FULL) *hp++ << BASEB;
                quasi_fnv(f, val);
                n -= 2;
        }
        if (n) {
                quasi_fnv(*hp, val);
        }
#else
        while (n--  > 0) {
                quasi_fnv(*hp, val);
                ++hp;
        }
#endif
        return val;
}


/*
 * hash_hash - Fowler/Noll/Vo 32 bit hash of a block
 *
 * given:
 *      hash    the HASH to quickhash
 *      val     initial hash value
 *
 * returns:
 *      a 32 bit QCKHASH value
 */
S_FUNC QCKHASH
hash_hash(HASH *hash, QCKHASH val)
{
        int i;

        /*
         * hash each USB8 in the BLOCK
         */
        for (i=0; i < hash->unionsize; ++i) {
                quasi_fnv(hash->h_union.data[i], val);
        }
        return val;
}


/*
 * blk_hash - Fowler/Noll/Vo 32 bit hash of a block
 *
 * given:
 *      blk     the BLOCK to hash
 *      val     initial hash value
 *
 * returns:
 *      a 32 bit QCKHASH value
 */
S_FUNC QCKHASH
blk_hash(BLOCK *blk, QCKHASH val)
{
        int i;

        if (blk == NULL)                /* block has no data */
                return val;

        /*
         * hash each USB8 in the BLOCK
         */
        if (blk->datalen > 0) {
                for (i=0; i < blk->datalen; ++i) {
                        quasi_fnv(blk->data[i], val);
                }
        }
        return val;
}