source: vis_dev/glu-2.3/src/sparse/cols.c

/*
 * $Id: cols.c,v 1.3 2002/09/10 00:00:12 fabio Exp $
 *
 */
#include <stdio.h>
#include "sparse_int.h"


/*
 *  allocate a new col vector 
 */
sm_col *
sm_col_alloc(void)
{
    register sm_col *pcol;

#ifdef FAST_AND_LOOSE
    if (sm_col_freelist == NIL(sm_col)) {
        pcol = ALLOC(sm_col, 1);
    } else {
        pcol = sm_col_freelist;
        sm_col_freelist = pcol->next_col;
    }
#else
    pcol = ALLOC(sm_col, 1);
#endif

    pcol->col_num = 0;
    pcol->length = 0;
    pcol->first_row = pcol->last_row = NIL(sm_element);
    pcol->next_col = pcol->prev_col = NIL(sm_col);
    pcol->flag = 0;
    pcol->user_word = NIL(char);                /* for our user ... */
    return pcol;
}


/*
 *  free a col vector -- for FAST_AND_LOOSE, this is real cheap for cols;
 *  however, freeing a rowumn must still walk down the rowumn discarding
 *  the elements one-by-one; that is the only use for the extra '-DCOLS'
 *  compile flag ...
 */
void
sm_col_free(sm_col *pcol)
{
#if defined(FAST_AND_LOOSE) && ! defined(COLS)
    if (pcol->first_row != NIL(sm_element)) {
        /* Add the linked list of col items to the free list */
        pcol->last_row->next_row = sm_element_freelist;
        sm_element_freelist = pcol->first_row;
    }

    /* Add the col to the free list of cols */
    pcol->next_col = sm_col_freelist;
    sm_col_freelist = pcol;
#else
    register sm_element *p, *pnext;

    for(p = pcol->first_row; p != 0; p = pnext) {
        pnext = p->next_row;
        sm_element_free(p);
    }
    FREE(pcol);
#endif
}


/*
 *  duplicate an existing col
 */
sm_col *
sm_col_dup(sm_col *pcol)
{
    register sm_col *pnew;
    register sm_element *p;

    pnew = sm_col_alloc();
    for(p = pcol->first_row; p != 0; p = p->next_row) {
        (void) sm_col_insert(pnew, p->row_num);
    }
    return pnew;
}


/*
 *  insert an element into a col vector 
 */
sm_element *
sm_col_insert(sm_col *pcol, int row)
{
    register sm_element *test, *element;

    /* get a new item, save its address */
    sm_element_alloc(element);
    test = element;
    sorted_insert(sm_element, pcol->first_row, pcol->last_row, pcol->length, 
                    next_row, prev_row, row_num, row, test);

    /* if item was not used, free it */
    if (element != test) {
        sm_element_free(element);
    }

    /* either way, return the current new value */
    return test;
}


/*
 *  remove an element from a col vector 
 */
void
sm_col_remove(sm_col *pcol, int row)
{
    register sm_element *p;

    for(p = pcol->first_row; p != 0 && p->row_num < row; p = p->next_row)
        ;
    if (p != 0 && p->row_num == row) {
        dll_unlink(p, pcol->first_row, pcol->last_row, 
                            next_row, prev_row, pcol->length);
        sm_element_free(p);
    }
}


/*
 *  find an element (if it is in the col vector)
 */
sm_element *
sm_col_find(sm_col *pcol, int row)
{
    register sm_element *p;

    for(p = pcol->first_row; p != 0 && p->row_num < row; p = p->next_row)
        ;
    if (p != 0 && p->row_num == row) {
        return p;
    } else {
        return NIL(sm_element);
    }
}

/*
 *  return 1 if col p2 contains col p1; 0 otherwise
 */
int 
sm_col_contains(sm_col *p1, sm_col *p2)
{
    register sm_element *q1, *q2;

    q1 = p1->first_row;
    q2 = p2->first_row;
    while (q1 != 0) {
        if (q2 == 0 || q1->row_num < q2->row_num) {
            return 0;
        } else if (q1->row_num == q2->row_num) {
            q1 = q1->next_row;
            q2 = q2->next_row;
        } else {
            q2 = q2->next_row;
        }
    }
    return 1;
}


/*
 *  return 1 if col p1 and col p2 share an element in common
 */
int 
sm_col_intersects(sm_col *p1, sm_col *p2)
{
    register sm_element *q1, *q2;

    q1 = p1->first_row;
    q2 = p2->first_row;
    if (q1 == 0 || q2 == 0) return 0;
    for(;;) {
        if (q1->row_num < q2->row_num) {
            if ((q1 = q1->next_row) == 0) {
                return 0;
            }
        } else if (q1->row_num > q2->row_num) {
            if ((q2 = q2->next_row) == 0) {
                return 0;
            }
        } else {
            return 1;
        }
    }
}


/*
 *  compare two cols, lexical ordering
 */
int 
sm_col_compare(sm_col *p1, sm_col *p2)
{
    register sm_element *q1, *q2;

    q1 = p1->first_row;
    q2 = p2->first_row;
    while(q1 != 0 && q2 != 0) {
        if (q1->row_num != q2->row_num) {
            return q1->row_num - q2->row_num;
        }
        q1 = q1->next_row;
        q2 = q2->next_row;
    }

    if (q1 != 0) {
        return 1;
    } else if (q2 != 0) {
        return -1;
    } else {
        return 0;
    }
}


/*
 *  return the intersection
 */
sm_col *
sm_col_and(sm_col *p1, sm_col *p2)
{
    register sm_element *q1, *q2;
    register sm_col *result;

    result = sm_col_alloc();
    q1 = p1->first_row;
    q2 = p2->first_row;
    if (q1 == 0 || q2 == 0) return result;
    for(;;) {
        if (q1->row_num < q2->row_num) {
            if ((q1 = q1->next_row) == 0) {
                return result;
            }
        } else if (q1->row_num > q2->row_num) {
            if ((q2 = q2->next_row) == 0) {
                return result;
            }
        } else {
            (void) sm_col_insert(result, q1->row_num);
            if ((q1 = q1->next_row) == 0) {
                return result;
            }
            if ((q2 = q2->next_row) == 0) {
                return result;
            }
        }
    }
}

int 
sm_col_hash(sm_col *pcol, int modulus)
{
    register int sum;
    register sm_element *p;

    sum = 0;
    for(p = pcol->first_row; p != 0; p = p->next_row) {
        sum = (sum*17 + p->row_num) % modulus;
    }
    return sum;
}

/*
 *  remove an element from a col vector (given a pointer to the element) 
 */
void
sm_col_remove_element(sm_col *pcol, sm_element *p)
{
    dll_unlink(p, pcol->first_row, pcol->last_row, 
                        next_row, prev_row, pcol->length);
    sm_element_free(p);
}


void
sm_col_print(FILE *fp, sm_col *pcol)
{
    sm_element *p;

    for(p = pcol->first_row; p != 0; p = p->next_row) {
        (void) fprintf(fp, " %d", p->row_num);
    }
}