espresso.c

主要进行大规模的电路综合

/*
 * Revision Control Information
 *
 * $Source: /projects/mvsis/Repository/mvsis-1.3/src/sis/espresso/espresso.c,v $
 * $Author: wjiang $
 * $Revision: 1.1.1.1 $
 * $Date: 2003/02/24 22:24:07 $
 *
 */
/*
 *  Module: espresso.c
 *  Purpose: The main espresso algorithm
 *
 *  Returns a minimized version of the ON-set of a function
 *
 *  The following global variables affect the operation of Espresso:
 *
 *  MISCELLANEOUS:
 *      trace
 *          print trace information as the minimization progresses
 *
 *      remove_essential
 *          remove essential primes
 *
 *      single_expand
 *          if true, stop after first expand/irredundant
 *
 *  LAST_GASP or SUPER_GASP strategy:
 *      use_super_gasp
 *          uses the super_gasp strategy rather than last_gasp
 *
 *  SETUP strategy:
 *      recompute_onset
 *          recompute onset using the complement before starting
 *
 *      unwrap_onset
 *          unwrap the function output part before first expand
 *
 *  MAKE_SPARSE strategy:
 *      force_irredundant
 *          iterates make_sparse to force a minimal solution (used
 *          indirectly by make_sparse)
 *
 *      skip_make_sparse
 *          skip the make_sparse step (used by opo only)
 */

#include "espresso.h"

pcover espresso(F, D1, R)
pcover F, D1, R;
{
    pcover E, D, Fsave;
    pset last, p;
    cost_t cost, best_cost;

begin:
    Fsave = sf_save(F);		/* save original function */
    D = sf_save(D1);		/* make a scratch copy of D */

    /* Setup has always been a problem */
    if (recompute_onset) {
	EXEC(E = simplify(cube1list(F)),     "SIMPLIFY   ", E);
	free_cover(F);
	F = E;
    }
    cover_cost(F, &cost);
    if (unwrap_onset && (cube.part_size[cube.num_vars - 1] > 1)
      && (cost.out != cost.cubes*cube.part_size[cube.num_vars-1])
      && (cost.out < 5000))
	EXEC(F = sf_contain(unravel(F, cube.num_vars - 1)), "SETUP      ", F);

    /* Initial expand and irredundant */
    foreach_set(F, last, p) {
	RESET(p, PRIME);
    }
    EXECUTE(F = expand(F, R, FALSE), EXPAND_TIME, F, cost);
    EXECUTE(F = irredundant(F, D), IRRED_TIME, F, cost);

    if (! single_expand) {
	if (remove_essential) {
	    EXECUTE(E = essential(&F, &D), ESSEN_TIME, E, cost);
	} else {
	    E = new_cover(0);
	}

	cover_cost(F, &cost);
	do {

	    /* Repeat inner loop until solution becomes "stable" */
	    do {
		copy_cost(&cost, &best_cost);
		EXECUTE(F = reduce(F, D), REDUCE_TIME, F, cost);
		EXECUTE(F = expand(F, R, FALSE), EXPAND_TIME, F, cost);
		EXECUTE(F = irredundant(F, D), IRRED_TIME, F, cost);
	    } while (cost.cubes < best_cost.cubes);

	    /* Perturb solution to see if we can continue to iterate */
	    copy_cost(&cost, &best_cost);
	    if (use_super_gasp) {
		F = super_gasp(F, D, R, &cost);
		if (cost.cubes >= best_cost.cubes)
		    break;
	    } else {
		F = last_gasp(F, D, R, &cost);
	    }

	} while (cost.cubes < best_cost.cubes ||
	    (cost.cubes == best_cost.cubes && cost.total < best_cost.total));

	/* Append the essential cubes to F */
	F = sf_append(F, E);                /* disposes of E */
	if (trace) size_stamp(F, "ADJUST     ");
    }

    /* Free the D which we used */
    free_cover(D);

    /* Attempt to make the PLA matrix sparse */
    if (! skip_make_sparse) {
	F = make_sparse(F, D1, R);
    }

    /*
     *  Check to make sure function is actually smaller !!
     *  This can only happen because of the initial unravel.  If we fail,
     *  then run the whole thing again without the unravel.
     */
    if (Fsave->count < F->count) {
	free_cover(F);
	F = Fsave;
	unwrap_onset = FALSE;
	goto begin;
    } else {
	free_cover(Fsave);
    }

    return F;
}