id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
7	Bug in ext:read-vector	jcunningham	somebody	"I have been trying to read large binary files of floating point data
using CMUCL (19c). I thought I would have to do it using some form of
FFI and went to comp.lang.lisp for help getting that working. I
succeeded. But Duane Rettig at Allegro suggested it would be easier to
use 'read-vector. So I tried that as follows:
{{{
(let ((vec (make-array 10 :element-type 'double-float)))
  (with-open-file (os ""d10.bin"")
    (read-vector vec os)
    (print vec)))
}}}
where ""d10.bin"" is a double-float binary file containing 10
elements. When I try to read the file it produces the following error:

Type-error in KERNEL::OBJECT-NOT-DOUBLE-FLOAT-ERROR-HANDLER:
   #\Null is not of type DOUBLE-FLOAT

Here is the C-code code I used to produce the file:
{{{
#include <iostream>
#include <fstream>
#include <complex>
using namespace std;
int main()
{
  int n=10;
  double *d = new double[n];
  for (int i=0; i<n; i++) 
    d[i] = i;
  FILE *of = fopen(""d10.bin"", ""wb"");
  fwrite(f,8,n,of);
  fclose(of);
  return 0;
}
}}}

Here is Duane's sample code that he says works in Allegro along with comments:
(copied from 
<http://groups.google.com/group/comp.lang.lisp/browse_thread/thread/67876101085aee82/05a20cfcd11f8fbe?hl=en#05a20cfcd11f8fbe>)
...................................................................
""You must be using a simple-streams implementation from another lisp.
Allegro CL doesn't have a KERNEL package.

What you're seeing above is a bug; you should report it to that
lisp's support team.

It works fine in Allegro CL (for which you can download the Express
Edition for free):

[edited formating for readability on Trac - jkc]
{{{
(defvar *x*
  (make-array 10 :element-type 'double-float
     :initial-contents
     (loop for i from 0.0d0 to 9.0d0 collect i))) 

#(0.0d0 1.0d0 2.0d0 3.0d0 4.0d0 5.0d0 6.0d0 7.0d0 8.0d0 9.0d0)

(with-open-file (s ""z.dat"" :direction :io
  :if-exists :overwrite
  :if-does-not-exist :create)
(write-vector *x* s))
80
(defvar *y* (make-array 10 :element-type 'double-float :initial-element 10.0d0))

(with-open-file (s ""z.dat"")
(read-vector *y* s))

*y*
#(0.0d0 1.0d0 2.0d0 3.0d0 4.0d0 5.0d0 6.0d0 7.0d0 8.0d0 9.0d0)
}}}
-- 
Duane Rettig""


Further correspondence with Raymond Toy corroborates this is a bug:

""Yes, this does appear to be a bug in the implementation of
read-vector.

You can, however, achieve what you want by opening the file with an
element-type of, say, (unsigned-byte 8), instead of the default
'character.

I'll have to read some more to understand how read-vector interacts
with the stream element type.  It seems, though, that the element-type
of the vector overrides the element-type of the stream, more or less.
Currently, a stream element type of character basically causes the
code to read in characters.

Ray""

If you need more information, let me know and I'll see what I can do.

-jeff
"	defect	closed	major		Core	19c	fixed	read-vector