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(in-package 3bz)
;;; some tuning parameters, and functions used in #+#.(...) to control
;;; features used by code
;;; deflate code tries to read/write/copy 64bits at a time, and uses
;;; ub64 buffer for bits when doing non-octet-unaligned reads, but
;;; that's slow if ub64 is a bignum, so this is used to switch to ub32
;;; where possible
(defun use-ub64 ()
'(:or)
;; on mezzano, ub64 is better on some files, worse on others, so leaving off for now
#+ (or (and 64-bit sbcl))
'(:and))
;;; similarly, adler32 checksum accumulates as many bytes as possible
;;; before doing mod, so we can either use :ub64, :ub32 or :fixnum
;;; versions of adler32 code depending on which is fastest
(defun use-adler32 (version)
(if (eql version
;; ub64 is fastest on 64bit sbcl, and seems better on mezzano too now
#+ (or mezzano (and sbcl x86-64))
:ub64
;; for now, just using fixnum elsewhere until there are
;; proper benchmarks. not sure if ub32 is faster than
;; fixnum anywhere, or if fixnum is good enough
#- (or mezzano abcl (and sbcl x86-64))
:fixnum
#+ abcl
:ub32
)
'(:and)
'(:or)))
;;; adler32 checksum is unrolled a bit to reduce loop overhead, this
;;; specifies how many iterations to unroll
;; todo: set this for more combinations of cpu/implementation once
;; there are benchmarks
(defconstant +adler32-unroll+
#+mezzano 16
#+sbcl 32
#- (or sbcl mezzano) 8)
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