Re: big strings

Raymond Toy (RT/EUS) writes:
 > >>>>> "WP" == Walter C Pelissero <[email protected]> writes:
 > 
 >     WP> Raymond Toy (RT/EUS) writes:
 >     >> Thanks for the replacement.  The only possible issue with the
 >     >> replacement would be performance.  BIT-BASH-COPY tries pretty hard
 >     >> to do word copies.  And BIT-BASH-COPY is intended to be able to
 >     >> copy arbitrary bit strings.  I don't know why it's limited to
 >     >> (unsigned-byte 27) offsets.  Perhaps to make sure the bit index
 >     >> stays as a 32-bit int?
 > 
 >     WP> This is what came to mind reading the error.  What I didn't understand
 >     WP> is why we get an error at all, being:
 > 
 >     WP>  2^27 > 17M   (way larger)
 > 
 > But the 17M is converted to a bit index and the bit index is greater
 > than 2^27.

Sorry, I failed to grasp the meaning of the "bit-" part.

 > As an experiment, I changed the constant max-bits in
 > code/bit-bash.lisp from 2^27 to most-positive-fixnum.  The comment
 > there says it's the maximum number of bits that can be delt [sic] with
 > during a single call.

I suppose one could compare the generated code (disassembling it) and
see if there is any degradation.

 > I don't see why it can't really handle at least
 > most-positive-fixnum number of bits or even #xffffffff number of
 > bits.

[I assume you meant 2^32 and not 2^2^32]

Wouldn't a 32-bit integer be too big to fit in a "simple" Lisp object
thus requiring a further indirection?


-- 
walter pelissero
http://www.pelissero.de