桶形移位器如何访问40位值？

嗨，我用DSPIC33FJ128GP802做了一些合成器。这个论坛有人告诉我我用的是桶形移位器，一个指令是16位移位。我读过桶形移位器可以处理40位的值，我怎么能访问40位的值？现在我使用一个暂时的无符号长来把最有意义的值换算进去，然后执行两次乘法。也许用40位值可以乘32位值，然后再换回去？提前感谢



      以下为原文

    Hi, i,m using the DSPIC33FJ128GP802 to make some synthesizers.
Some one in this forum told me i was using the barrel shifter, 16 bit shift in 1 instruction.

I readed the barrel shifter can handle a 40 bits value, how can i access a 40 bit value ?
Now i am using a temporary unsigned long to shift the most significant into, and perform the multiply twice.

Maybe with a 40 bit value i could multiply a 32 bit value, and shift back again ?
Thanks in advance