Thanks Marc, I see the point in bignums conversion and I am trying your suggested approach. Mostly I have u64vectors with multiple elements to use in the bitwise operation and being able to reference / use one of the arbitrary elements in the vector could avoid in converting to/from bignums using u64vector-ref / u64-vector-set! , if I understood your point.
I tried the following code but it is not working
(c-declare "#define ELEM_N(u64vect,index) ___BODY_AS(u64vect,___tSUBTYPED)[index]")
(define-macro (u64-xor! v1 i1 v2 i2) `(##c-code "ELEM_N(___ARG1,___ARG2) ^= ELEM_N(___ARG3,___ARG4);" ,v1 ,i1 ,v2 ,i2))
running
(define u64one-bits (u64vector 1)) (define v7 (make-u64vector 10 0)) (pretty-print v7) (u64-xor! v7 0 u64one-bits 0) (u64-xor! v7 1 u64one-bits 0) ; trying to use the second element with index 1 (pretty-print v7)
I get the following
#u64(0 0 0 0 0 0 0 0 0 0) #u64(1 0 0 0 1 0 0 0 0 0)
… of course that was an easy but incorrect guess ;-) Is there a way to declare a macro that gets the index of the vector as parameter?
Thanks Paolo
Il giorno 27 apr 2020, alle ore 00:20, Marc Feeley feeley@iro.umontreal.ca ha scritto:
Marc
On Apr 26, 2020, at 9:48 AM, Paolo pmontrasi@gmail.com wrote:
Hi Brad, thank you for your suggestion. I ended up in testing something similar to the following example
(define (u64-xor . args-list) (##bignum.normalize! (fold (lambda (x big) (let ((x-big (if (fixnum? x) (##fixnum->bignum x) x))) (##bignum.adigit-bitwise-xor! big 0 x-big 0) big)) (##bignum.make 2 ##bignum.adigit-zeros #f) args-list)))
it worked but with no noticeable improvements and this fact helped me in looking elsewhere to find speed problems … I found a lot of them in my code of course ;-)
Well I tried to do my best to fix most of the performance issues and I am now pretty happy with what I have come to, therefore I point you to my code in case you are looking for a fun "chess scheme" challenge.
https://github.com/pmon/coronachess
Thank you for your help, my best Paolo
Nice! I’ll have to try it out… As you noticed the name Gambit has its origins in chess… I used to play regularly. A gambit is a kind of scheme… and it is a calculated risk (which felt quite appropriate for my PhD work which was also risky).
To do high speed calculations on raw 64 bit integers, I would tend to use u64vectors (or even u8vectors) to store the 64 bit integers and to drop down to C when some operation on these integers must be done without creating bignums. Something along these lines:
(declare (standard-bindings) (extended-bindings) (not safe) )
(c-declare "#define ELEM0(u64vect) ___BODY_AS(u64vect,___tSUBTYPED)[0]")
(define-macro (u64-xor! v1 v2) ;; v1[0] = v1[0] ^ v2[0] `(##c-code "ELEM0(___ARG1) ^= ELEM0(___ARG2);" v1 v2))
(define v1 (u64vector #x0123456789ABCDEF)) (define v2 (u64vector #x00FF00FF00FF00FF))
(println (number->string (u64vector-ref v1 0) 16)) (println (number->string (u64vector-ref v2 0) 16))
(u64-xor! v1 v2)
(println (number->string (u64vector-ref v1 0) 16))
You could create a small library of such macros for the various 64 bit operations, and try to avoid as much as possible conversions to and from bignums which probably incurs a high overhead in your application.
Marc