Adam Preble wrote:
> Hello,
> I am working on a library that uses libftdi 0.16 (and libusb 0.1.12) to
> communicate with a FT245RL. All of my work is taking place on a Mac (Intel,
> 10.5.6) but we're keeping the library code portable. I've written a C++
> console app that uses the library and everything works great there.
>
> The problems arose when I started trying to call the library from a Cocoa
> app. My library can still enumerate all of the devices and open one, but
> when it calls to write to the device via ftdi_write_data() it returns 0
> bytes written.
>
> I've used Xcode to step down through the code, all the way into the libusb
> bulk write code but haven't been able to observe the actual problem.
> Sometimes Xcode/gdb will print out the following while stepping over the
> write call:
>
> Program received signal: “EXC_BAD_ACCESS”.
>
> Cannot access memory at address 0x6f697377
>
> Cannot access memory at address 0x6f697377
That's "oisw", which makes this look like you've corrupted the address
of your buffer. Do you use the substring "wsio" anywhere in your code?
You could try running the non-cocoa version under valgrind to ensure
there are no memory related bugs.
libftdi will only return 0 from ftdi_write_data if the underlying
usb_bulk_write returns 0. For darwin, that seems to be a mess of code
involving a "CFRunLoop" that I don't understand, but maybe using Cocoa
is affecting that somehow?
-jim
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