CREATE OR REPLACE FUNCTION GET_WEEKEND_SECONDS
(
      P_START_DATE DATE,
      p_END_DATE DATE
)
RETURN NUMBER
IS
CURSOR cur_weekend_minutes IS
SELECT 
CASE WHEN (weekend_day_num = MIN(weekend_day_num) OVER(PARTITION BY START_DATE)/*START_EDGE_ROW. This determines first weekend in order from old to most recent*/ )
        THEN CASE WHEN start_date <= (MIN(WEEKENDDAY_START) OVER(ORDER BY START_DATE))/*first_weekend_start*/THEN 24*60
                  WHEN START_DATE > (MIN(WEEKENDDAY_START) OVER(ORDER BY START_DATE))/*first_weekend_start*/
                    THEN ROUND((MIN(WEEKENDDAY_END) OVER(PARTITION BY START_DATE)/*first_weekend_end*/ - START_DATE)*24*60, 0)
             ELSE 0 END
      WHEN (weekend_day_num = MAX(weekend_day_num) OVER(PARTITION BY END_DATE)/*END_EDGE_ROW. This determines last weekend in order from old to most recent*/)
        THEN CASE WHEN END_DATE >= MAX(weekendday_end) OVER(PARTITION BY end_date)/*last_weekend_end*/THEN 24*60
                  when END_DATE < max(WEEKENDDAY_END) over(partition by END_DATE)/*last_weekend_end*/
                    THEN ROUND((END_DATE - MAX(WEEKENDDAY_START) OVER(PARTITION BY END_DATE)/*last_weekend_start*/)*24*60 , 0)
             ELSE 0 END
 ELSE 24 END AS WEEKEND_MINUTES
FROM
(
 SELECT
 ROWNUM WEEKEND_DAY_NUM
 ,P_START_DATE START_DATE
 ,p_END_DATE END_DATE
 ,trunc(p_START_DATE) + level - 1 WEEKENDDAY_START
 ,TO_DATE(TO_CHAR((TRUNC(p_START_DATE) + level - 1), 'DD-MM-YYYY') || ' 23:59', 'DD-MM-YYYY HH24:MI') as WEEKENDDAY_END
 FROM DUAL
 CONNECT BY LEVEL < = CEIL((p_END_DATE - p_START_DATE)) + 1
)
WHERE TO_CHAR (WEEKENDDAY_START, 'DY') IN ('SAT', 'SUN');

v_total_weekend_minutes NUMBER(23,0) := 0;
v_weekend_minutes_rec cur_weekend_minutes%ROWTYPE;

BEGIN
OPEN cur_weekend_minutes;
LOOP
  FETCH cur_weekend_minutes INTO v_weekend_minutes_rec;
  EXIT when cur_weekend_minutes%NOTFOUND;
  v_total_weekend_minutes := v_total_weekend_minutes + v_weekend_minutes_rec.WEEKEND_MINUTES;
END LOOP;
CLOSE cur_weekend_minutes;
RETURN v_total_weekend_minutes * 60.00;
END;

SELECT GET_WEEKEND_MINUTES(TO_DATE('22-JUN-2014 23:46:17', 'DD-MON-YYYY HH24:MI:SS'), TO_DATE('23-JUN-2014 01:51:52', 'DD-MON-YYYY HH24:MI:SS')) FROM DUAL;

start_date - 22-JUN-2014 23:46:17
end of first weekend day in my time interval -  22-JUN-2014 23:59:59
select (to_date('22-JUN-2014 23:59:59', 'DD-MON-YYYY HH24:MI:SS') - to_date('22-JUN-2014 23:46:17', 'DD-MON-YYYY HH24:MI:SS'))*24*60*60+1 from dual;

WEEKEND_SECONDS
823

WITH parameters AS (
                    SELECT  TO_DATE('22-JUN-2014 23:46:17', 'DD-MON-YYYY HH24:MI:SS') start_dt,
                            TO_DATE('23-JUN-2014 01:51:52', 'DD-MON-YYYY HH24:MI:SS') end_dt
                      FROM  DUAL
                   ),
          dates AS (
                    SELECT  GREATEST(trunc(start_dt) + level - 1,start_dt) start_dt,
                            LEAST(trunc(start_dt) + level,end_dt) end_dt
                      FROM  parameters
                      WHERE start_dt + level - 1 - trunc(start_dt + level - 1,'IW') >= 5
                      CONNECT BY trunc(start_dt) + level <= trunc(end_dt) + 1
                   )
SELECT  ROUND(SUM(end_dt - start_dt) * 1440) weekend_minutes,
        SUM(end_dt - start_dt) * 86400 weekend_seconds
  FROM  dates
/

WEEKEND_MINUTES WEEKEND_SECONDS
--------------- ---------------
             14             823

SQL>

trunc(start_dt + level - 1,'IW')

WHERE start_dt + level - 1 - trunc(start_dt + level - 1,'IW') >= 5