Re: [f-cpu] Shift and rotate instruction

[Michael Riepe <michael@stud.uni-hannover.de>]

On Wed, Mar 13, 2002 at 05:22:43PM +0100, Cedric BAIL wrote:
> Because I find some wrong latex code in rotl.tex, I wasn't able to
> understand how shift and rotate are done when you are in a SIMD mode ?
> 
> I mean, is each chunk of the register who indicate how many bits to shift
> specifing each chunk of the register who contain the bits to shift, or we
> only use the first chunk of R2 to specifie this number ?

In the current implementation, there is a common shift count for all
chunks, taken from the least significant 3...6 bits.

> A second question, that is only for logical reason, is for all 3 members
> shift and rotate instructions R2 means the number of bits to shift, and
> R3 the bits to shift, right ?

The syntax should be:

	shiftxy shift_count, source, destination

where shift_count may be a register or an immediate operand.
That is, r3 is the shift count, and the contents of r2 are shifted and
the result placed into r1.

-- 
 Michael "Tired" Riepe <Michael.Riepe@stud.uni-hannover.de>
 "All I wanna do is have a little fun before I die"
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