Ah, of course, John! I got them mixed up.
In that case Chris, I think your color struct might fit quite nicely
into a make-s32vector. I did not test the code below, but something like
it might work:
(define-foreign-type color* s32vector
(lambda (a) (assert (= 4 (s32vector-length a))) a))
(define color s32vector)
(define (rgb-to-hsl color)
(let ((return (make-s32vector 3)))
((foreign-lambda*
void ((color input) (color output))
"rgb_to_hsl((struct color*)input, &output[0], &output[1],
&output[2])") color return)
return))
(rgb-to-hsl (color 0 255 0 0)) ;; <-- should in theory return a
;; 3-element s32vector with your hue,
;; sat and lum.
Note the cast from s32vector (int*) to struct color*.
Cheers,
K.
On Sat, Sep 7, 2013 at 4:33 PM, John Cowan <address@hidden
<mailto:address@hidden>> wrote:
Kristian Lein-Mathisen scripsit:
> Because size of an "int" can generally be either 32 or 64-bit
depending
> on your architecture, the srfi-4 vectors are possible better suited
> for floats and doubles where the sizes are all set. It's worth
knowing
> about them though.
Actually, there are essentially no architectures on which "int" is
anything but 32 bits: unless you have an ancient Cray running Unicos
(modern ones run Linux), a (now-defunct) HAL Systems port of Solaris,
or an IBM PC/AT, you don't have to worry about that. What does vary is
"long", which is 32 bits on 32-bit systems and Win64, and 64 bits on
non-Windows 64-bit systems.
--
John Cowan http://ccil.org/~cowan address@hidden <mailto:address@hidden>
SAXParserFactory [is] a hideous, evil monstrosity of a class that should
be hung, shot, beheaded, drawn and quartered, burned at the stake,
buried in unconsecrated ground, dug up, cremated, and the ashes tossed
in the Tiber while the complete cast of Wicked sings "Ding dong, the
witch is dead." --Elliotte Rusty Harold on xml-dev