Re: [Chicken-users] Re: time/date

[felix]

Anthony Carrico wrote:
> On Thu, Mar 27, 2003 at 03:26:46PM +0100, Felix Winkelmann wrote:
>
> > Hi!
> >
> > Just change the "int" argument type-specifier in posix.scm (line 1137)
> > to "integer".
> >
> > Sorry.
>
>
> I think I'm still missing something. When working with time values,
> how do I specify 32bit integer literals, do 32bit arithmetic, etc.?
>
> (define seconds->string2
>   (let ([ctime (foreign-lambda c-string "C_ctime" integer)])
>     (lambda (secs)
>       (let ([str (ctime secs)])
>         (unless str (##sys#error 'seconds->string2 "can not convert seconds to 
> string" secs))
>         str))))
>
> (display (seconds->string2 1073741823)) (newline)
> (display (seconds->string2 1073741824)) (newline)
>
> bash-2.05b$ chicken test.scm
> compiling `test.scm' ...
> Warning: exact literal exceeds range in line 9
> "1073741824"

Never mind that warning. It is just there to remind you that
the integer constant will be compiled as a flonum literal.
(Should I remove that warning).

Everything that doesn't fit into a fixnum (31-bit signed), will
be coerced to a flonum (64-bit double). Everything beyond what
fits into that will have to wait for bignum support.

Passing flonums to C code that wants 32-bit ints is safe, as
long as the value fits into that range (and as long as you use
the "integer" type-specifier. "int" is only for fixnum-range.
That is not very intuitive, I admit).


cheers,
felix