cdm/src/main/java/ucar/unidata/io/Swap.java
static public double swapDouble(byte[] b, int offset) {
        long accum = 0;
        long shiftedval;
        for (int shiftBy = 0, i = offset; shiftBy < 64; shiftBy += 8, i++) {
            shiftedval = ((long) (b[i] & 0xff)) << shiftBy;
            accum      |= shiftedval;
        }
        return Double.longBitsToDouble(accum);
    }
static public double swapDouble(byte[] b, int offset) {
        long accum = 0;
        long shiftedval;
        for (int shiftBy = 0, i = offset; shiftBy < 64; shiftBy += 8, i++) {
            shiftedval = ((long) (b[i] & 0xff)) << shiftBy;
            accum      |= shiftedval;
        }
        return Double.longBitsToDouble(accum);
    }
Returns the double resulting from reversing 8 bytes at a specified
offset in a byte array.

@param  b       the byte array
@param  offset  the offset of the first byte
@return         the double represented by the bytes
<code>b[offset+7], b[offset+6], ..., b[offset]</code>