out-of-bound write

[Zimmermann Paul]

       Torbjörn,

> The return value is the number of valid limbs written to @var{rp}.

I find this hard to understand. What is a "valid" limb? I would say instead
(assuming this is what you mean):

"The converted value is @{@var{rp}, at var{rn}@} where @var{rn} is the return
value. If the most significant input byte @math{@var{str}[0]} is non zero,
then @var{rp[rn-1]} will be non zero. If @math{@var{str}[0]} is zero,
then @var{rp[rn-1]} might be zero."

Paul