So, is there any way that a 32 bit VB6 ActiveX dll or a32 bit VB6 ActiveX exe could access a 64 bit SQLite dll? All this only comes into play for me when using 64 bit VBA in Excel. I have no problem to access the 64 bit SQLite dll from 64 bit VBA.
RBS On Sun, May 15, 2016 at 7:12 PM, Richard Damon <Richard at damon-family.org> wrote: > On 5/15/16 1:00 AM, dandl wrote: > >> But I think if you compile code for the x64 processor chip and call it >>>> from x86 or vice versa then either it doesn't work or you pay a high >>>> price for thunking from one to the other. I think that's unavoidable >>>> regardless of OS. >>>> >>> Right: doesn't work. There's no performance penalty because there's no >>> 32-64 bit thunking layer. >>> >>> >>> https://blogs.msdn.microsoft.com/oldnewthing/20081020-00/?p=20523 >>> >> An interesting post, but not I think from someone with a deep >> understanding >> of the matter. >> >> IMHO it would be perfectly possible to chunk either way, within the >> limitations of a 4GB address space. The WOW64 layer already provides the >> means for x86 apps to call the x64 Windows API. A thunk can do anything, >> unless it's physically impossible or blocked by policy. >> >> Regards >> David M Bennett FACS >> >> Andl - A New Database Language - andl.org >> >> You can thunk an arbitrary 32 bit module to 64 bit code because the > memory accessibly by the 32 bit code is all accessible by the 64 bit code. > The converse doesn't work. Either the 64 bit code needs to make sure it > puts the data in the lower 4GB, or the thunk layer needs to know enough > about the data to copy it. > > This works for WOW64, as the 64 bit side is code designed to make it work > with the thunking layer. > > For arbitrary 64 bit code, the thunking layer won't know enough about what > needs to be copied into accessible memory. > > -- > Richard Damon > > > _______________________________________________ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users >
