C type buffer copy

[[EMAIL PROTECTED]]

Hello,

How does Python deal with C type memory buffers. Does Python return
everything as an object irrespective of the data type?

Here's what i am trying to achieve?

testCode(unsigned char buf, unsigned long len)
{
unsigned long data=0x0;
while (len--)
{
*buf++ = (unsigned char)data++
}

}

What's the best way to deal with this in python?

-Joe

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Re: C type buffer copy

[Ivan Van Laningham]

Hi All--

def testCode(data):
   buf=data[:]
   # and I hope you're going to do something with buf,
   # because otherwise this function's a bit of a waste;-)

[EMAIL PROTECTED] wrote:
 
 Hello,
 
 How does Python deal with C type memory buffers. Does Python return
 everything as an object irrespective of the data type?
 
 Here's what i am trying to achieve?
 
 testCode(unsigned char buf, unsigned long len)
 {
 unsigned long data=0x0;
 while (len--)
 {
 *buf++ = (unsigned char)data++
 }
 
 }
 
 What's the best way to deal with this in python?
 

Metta,
Ivan
--
Ivan Van Laningham
God N Locomotive Works
http://www.andi-holmes.com/
http://www.foretec.com/python/workshops/1998-11/proceedings.html
Army Signal Corps:  Cu Chi, Class of '70
Author:  Teach Yourself Python in 24 Hours
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Re: C type buffer copy

[Neil Hodgson]

Joe:

 testCode(unsigned char buf, unsigned long len)
 {
 unsigned long data=0x0;
 while (len--)
 {
 *buf++ = (unsigned char)data++

   This C code will crash since buf is declared as an unsigned char, not 
an unsigned char*. Stop thinking in terms of translating low level C 
because Python is a higher level language and does not have machine 
address pointers. You should be implementing the intent of your design 
which we can't determine from tiny incorrect snippets. For example, we 
can't determine if the intent is to create a new string, translation: 
''.join([chr(x) for x in range(len)]), or if you are modifying an 
existing sequence or inserting into a sequence. It is also impossible to 
tell if you should be using a list, array or string for this job.

   Neil
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Re: C type buffer copy

[Paul Rubin]

[EMAIL PROTECTED] [EMAIL PROTECTED] writes:
 What's the best way to deal with this in python?

I can't tell what you're trying to do.  If you want an array
containing the numbers 0,1,...,n-1, just say 
  buf = range(n)
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