How to read from an EvtIoRead buffer?

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When an application issues a read() request to my driver, the framework
creates a single intermediate buffer that my driver fills. The framework
then copies the output data from the intermediate buffer to the application's
output buffer.

How can I read from this intermediate buffer?

I would like the application to pass the following buffer to my driver:
| address | buffer |

If I could read the address portion out of the buffer, fetch data from that
particular address in HW, and fill the buffer within the buffer with that
data I'd be golden. However, as it is, I can't do a
WdfRequestRetrieveInputBuffer() from within my EvtRead() routine.

How else can I do this without creating a seperate IOCTL that just keeps
track of the next address to read from?

Thanks!!!!
.

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