Re: [Chicken-users] Getting C file handle from port?

[Jeronimo Pellegrini]

On Sat, Mar 20, 2010 at 04:10:16PM +0100, Peter Bex wrote:
> On Sat, Mar 20, 2010 at 04:01:16PM +0100, Peter Bex wrote:
> > There's even a macro for that: C_port_file.
> 
> I added this to the "C interface" documentation. It should appear on
> the wiki shortly.

Thanks Peter and Thomas for your help!

An interesting thing: reading 1000000 floating-point numbers
takes 8.7 seconds using the procedure read, but this:

(define read-flonum
  (foreign-lambda* double ((scheme-object port))
              "double d; \n
               int x = fscanf(C_port_file(port), \" %lf\", &d); \n
               if (x != 1) {
                   puts(\"Error: couldn't read floating-point number\");
                   exit(-1);
               } else C_return(d);\n "))

is 10x faster (0.85 s). It's roughly as fast as a  pure C
implementation I used for comparison.

It's a quick hack, but illustrates what I'd like to do: read
a large matrix (much larger than the one in this example) quickly 
(I don't want the safety and type checks for this procedure;
the matrix may need to be read several times from several different
files).

Again, thanks a lot guys!

J.