}
static bool _valid_monster_location(const mgen_data &mg, 
                                    const coord_def &mg_pos)
{
    const int htype = (mons_class_is_zombified(mg.cls) ? mg.base_type
                                                       : mg.cls);
    dungeon_feature_type grid_wanted =
        habitat2grid(mons_habitat_by_type(htype));
    if (!in_bounds(mg_pos))
        return (false);
    // Occupied?
    if (mgrd(mg_pos) != NON_MONSTER || mg_pos == you.pos())
        return (false);
    // Is the monster happy where we want to put it?
    if (!grid_compatible(grid_wanted, grd(mg_pos), true))
        return (false);
    if (mg.behaviour != BEH_FRIENDLY && is_sanctuary(mg_pos.x, mg_pos.y))
        return (false);
    // Don't generate monsters on top of teleport traps.
    // (How did they get there?)
    int trap = trap_at_xy(mg_pos.x, mg_pos.y);
    if (trap >= 0)
    {
        if (!_can_place_on_trap(mg.cls, env.trap[trap].type))
            return (false);
    }
    return (true);
}
static bool _valid_monster_location(mgen_data &mg)
{
    return _valid_monster_location(mg, mg.pos);

        const int htype = (mons_class_is_zombified(mg.cls) ? mg.base_type
                                                           : mg.cls);
        dungeon_feature_type grid_wanted =
            habitat2grid( mons_habitat_by_type(htype) );

            // Let's recheck these even for PROX_NEAR_STAIRS, just in case.
            // Occupied?
            if (mgrd(mg.pos) != NON_MONSTER || mg.pos == you.pos())

            if (!_valid_monster_location(mg))

            // Is the monster happy where we want to put it?
            if (!grid_compatible(grid_wanted, grd(mg.pos), true))
                continue;

            if (!unforbidden( mg.pos, mg.map_mask ))

            if (!unforbidden(mg.pos, mg.map_mask))

            // Don't generate monsters on top of teleport traps.
            // (How did they get there?)
            int trap = trap_at_xy(mg.pos.x, mg.pos.y);
            if (trap >= 0)
            {
                if (!_can_place_on_trap(mg.cls, env.trap[trap].type))
                    continue;
            }

            // Let's recheck these even for PROX_NEAR_STAIRS, just in case.

    }
    else if (!_valid_monster_location(mg))
    {
        // Sanity check that the specified position is valid.
        return (-1);

    dungeon_feature_type grid_wanted = DNGN_UNSEEN;

        grid_wanted = habitat2grid( mons_habitat_by_type(htype) );

            if (!in_bounds(fpos))
                continue;
            // Occupied?
            if (mgrd(fpos) != NON_MONSTER || fpos == you.pos())
                continue;
            if (!grid_compatible(grid_wanted, grd(fpos), true))
                continue;
            if (mg.behaviour != BEH_FRIENDLY && is_sanctuary(fpos.x, fpos.y))
                continue;
            // Don't generate monsters on top of teleport traps.
            // (How do they get there?)
            int trap = trap_at_xy(fpos.x, fpos.y);
            if (trap >= 0 && !_can_place_on_trap(mg.cls, env.trap[trap].type))
                continue;
            // Cool.. passes all tests.
            break;

            if (_valid_monster_location(mg, fpos))
                break;