Rotating through a four-bit nibble

   No, it's not pornographic (look over in rtlToronto - I hear it's a fun
thread). But I'm working in NQC, and I need to rotate the bit series in a 4-bit
(or 8-bit) nibble embedded in a 16-bit word. Annoying. Any suggestions? Masking
the desired four bits out of a storage variable and into a temporary variable
four times (so it's a repeating pattern) and then rotating and masking out the
desired sequence might work, but is there a better way? Bit-level manipulation
is not my strong suite.

(x's here are "something else" that I may wish to keep intact, y is garbage or
potentially trashed bits)

stored sequence in 16-bit word:        xxxx xxxx 0110 xxxx
4-bit nibble copied across temporary:  xxxx 0110 0110 0110
left shift temporary, say, twice:      xx01 1001 1001 10yy
mask out one nibble back into storage: xxxx xxxx 1001 xxxx

There's got to be a better way. I'm using NQC, so I'm stuck with those big
16-bit words and basic operations like bit logic, shifts, and interger division
(and of course modulo division).

   Anybody?

-- 
Brian Davis