OpenEuphoria

Re: 64 bit integers (accessing files > 4Gb)

• Posted by CChris <christian.cuvier at agriculture.gouv.fr> Jan 31, 2007
• 471 views

Chris Bensler wrote:
> 
> How do I access file data > 4Gb?
> 
> The Windows API has SetFilePointerEx() but it requires large integers.
> Is it possible to deal with large ints in Eu using atoms?
> 
> Chris Bensler
> ~ The difference between ordinary and extraordinary is that little extra ~
> <a href="http://empire.iwireweb.com">http://empire.iwireweb.com</a> - Empire
> for Euphoria

I didn't test this, but....

In the wrapper for your routine, replace the large_integer by a C_LONG and 
a C_ULONG. Then, pass the high dword in the C_LONG and the low dword in the 
C_LONG, both using atoms as usual. This results in

constant kernel32=open_dll("kernel32.dll"),
sfpx=define_c_func(kernel32,"SetFilePointerEx",
  {C_POINTER,C_LONG,C_ULONG,C_POINTER,C_ULONG},C_BOOL)

You'd pass 5 atoms to c_func() when calling the function. You'd also 
poke4() 2 atoms at the place pointed to by the 4th arg, which is the
lpNewFilePointer parameter. 

If the large integer is pushed on the stack, which I expect on 32 bit 
machines, this hack should work, since it generates the stack layout the 
routine expects. Perhaps using a "+" to force a _cdecl call is safer. 
Again, I haven't tested this...

HTH
CChris