primes.c 3.81 KB
Newer Older
Alan Mishchenko committed
1 2 3 4 5 6 7 8 9 10 11
/*
 * Revision Control Information
 *
 * $Source$
 * $Author$
 * $Revision$
 * $Date$
 *
 */
#include "espresso.h"

12 13 14
ABC_NAMESPACE_IMPL_START


Alan Mishchenko committed
15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173
static bool primes_consensus_special_cases();
static pcover primes_consensus_merge();
static pcover and_with_cofactor(); 


/* primes_consensus -- generate primes using consensus */
pcover primes_consensus(T)
pcube *T;            /* T will be disposed of */
{
    register pcube cl, cr;
    register int best;
    pcover Tnew, Tl, Tr;

    if (primes_consensus_special_cases(T, &Tnew) == MAYBE) {
    cl = new_cube();
    cr = new_cube();
    best = binate_split_select(T, cl, cr, COMPL);

    Tl = primes_consensus(scofactor(T, cl, best));
    Tr = primes_consensus(scofactor(T, cr, best));
    Tnew = primes_consensus_merge(Tl, Tr, cl, cr);

    free_cube(cl);
    free_cube(cr);
    free_cubelist(T);
    }

    return Tnew;
}

static bool 
primes_consensus_special_cases(T, Tnew)
pcube *T;            /* will be disposed if answer is determined */
pcover *Tnew;            /* returned only if answer determined */
{
    register pcube *T1, p, ceil, cof=T[0];
    pcube last;
    pcover A;

    /* Check for no cubes in the cover */
    if (T[2] == NULL) {
    *Tnew = new_cover(0);
    free_cubelist(T);
    return TRUE;
    }

    /* Check for only a single cube in the cover */
    if (T[3] == NULL) {
    *Tnew = sf_addset(new_cover(1), set_or(cof, cof, T[2]));
    free_cubelist(T);
    return TRUE;
    }

    /* Check for a row of all 1's (implies function is a tautology) */
    for(T1 = T+2; (p = *T1++) != NULL; ) {
    if (full_row(p, cof)) {
        *Tnew = sf_addset(new_cover(1), cube.fullset);
        free_cubelist(T);
        return TRUE;
    }
    }

    /* Check for a column of all 0's which can be factored out */
    ceil = set_save(cof);
    for(T1 = T+2; (p = *T1++) != NULL; ) {
    INLINEset_or(ceil, ceil, p);
    }
    if (! setp_equal(ceil, cube.fullset)) {
    p = new_cube();
    (void) set_diff(p, cube.fullset, ceil);
    (void) set_or(cof, cof, p);
    free_cube(p);

    A = primes_consensus(T);
    foreach_set(A, last, p) {
        INLINEset_and(p, p, ceil);
    }
    *Tnew = A;
    set_free(ceil);
    return TRUE;
    }
    set_free(ceil);

    /* Collect column counts, determine unate variables, etc. */
    massive_count(T);

    /* If single active variable not factored out above, then tautology ! */
    if (cdata.vars_active == 1) {
    *Tnew = sf_addset(new_cover(1), cube.fullset);
    free_cubelist(T);
    return TRUE;

    /* Check for unate cover */
    } else if (cdata.vars_unate == cdata.vars_active) {
    A = cubeunlist(T);
    *Tnew = sf_contain(A);
    free_cubelist(T);
    return TRUE;

    /* Not much we can do about it */
    } else {
    return MAYBE;
    }
}

static pcover 
primes_consensus_merge(Tl, Tr, cl, cr)
pcover Tl, Tr;
pcube cl, cr;
{
    register pcube pl, pr, lastl, lastr, pt;
    pcover T, Tsave;

    Tl = and_with_cofactor(Tl, cl);
    Tr = and_with_cofactor(Tr, cr);

    T = sf_new(500, Tl->sf_size);
    pt = T->data;
    Tsave = sf_contain(sf_join(Tl, Tr));

    foreach_set(Tl, lastl, pl) {
    foreach_set(Tr, lastr, pr) {
        if (cdist01(pl, pr) == 1) {
        consensus(pt, pl, pr);
        if (++T->count >= T->capacity) {
            Tsave = sf_union(Tsave, sf_contain(T));
            T = sf_new(500, Tl->sf_size);
            pt = T->data;
        } else {
            pt += T->wsize;
        }
        }
    }
    }
    free_cover(Tl);
    free_cover(Tr);

    Tsave = sf_union(Tsave, sf_contain(T));
    return Tsave;
}


static pcover
and_with_cofactor(A, cof)
pset_family A;
register pset cof;
{
    register pset last, p;

    foreach_set(A, last, p) {
    INLINEset_and(p, p, cof);
    if (cdist(p, cube.fullset) > 0) {
        RESET(p, ACTIVE);
    } else {
        SET(p, ACTIVE);
    }
    }
    return sf_inactive(A);
}
174 175
ABC_NAMESPACE_IMPL_END