#include <grass/gis.h>
int G_cell_stats_histo_eq (
    struct Cell_stats *statf,
    CELL min1,CELL max1, /* input range to be rescaled */
    CELL min2,CELL max2, /* output range */
    int zero,        /* include zero if min1 <= 0 <= min2 ? */
    void (*func)(CELL,CELL,CELL))
{
    long count, total;
    CELL prev = 0;
    CELL cat;
    CELL x;
    CELL newcat = 0;
    int first;
    double span, sum;
    double range2;


    if (min1 > max1 || min2 > max2) return 0;

    total = 0;
    G_rewind_cell_stats (statf);
    while (G_next_cell_stat (&cat, &count, statf))
    {
	if (cat < min1) continue;
	if (cat > max1) break;
	if (cat == 0 && !zero) continue;

	total += count;
    }
    if (total <= 0) return 0;

    range2 = max2 - min2 + 1;
    span = total/range2;

    first = 1;
    sum = 0;

    G_rewind_cell_stats (statf);
    while (G_next_cell_stat (&cat, &count, statf))
    {
	if (cat < min1) continue;
	if (cat > max1) break;
	if (cat == 0 && !zero) continue;

	x = (sum + (count/2.0))/span;
	if (x < 0) x = 0;
	x += min2;
	sum += count;

	if (first)
	{
	    prev = cat;
	    newcat = x;
	    first = 0;
	}
	else if (newcat != x)
	{
	    func (prev, cat-1, newcat);
	    newcat = x;
	    prev = cat;
	}
    }
    if (!first)
    {
	func (prev, cat, newcat);
	if (!zero && min1 <= 0 && max1 >= 0)
	    func ((CELL)0, (CELL)0, (CELL)0);
    }

    return first == 0;
}
