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differences of absolute locations

I want an instance of a structure to be put at a specific address in xdata. What is the difference between these declarations:

#define tSetupPacket (* (tDEVICE_REQUEST xdata *)0xFF00)

tDEVICE_REQUEST xdata tSetupPacket _at_ 0xFF00;

It seems that the second behaves incorrectly.
There is also an opportunity to declare a structure at absolute locaiton by #pragma memory segments (supported by non-Keil C or Keil linker).
What is the best choice?

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0 Valentin Tihhomirov over 22 years ago in reply to Jon Ward

Thanks.
All you agree that the second form is a valid one. Nevertheless, it is always zero, i.e. writing to the structure's fields does not modify it. So, something is still wrong.
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0 Valentin Tihhomirov over 22 years ago in reply to Jon Ward

Thanks.
All you agree that the second form is a valid one. Nevertheless, it is always zero, i.e. writing to the structure's fields does not modify it. So, something is still wrong.
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