P1076 Minutes from September 10, 2020

Attendees

• Jim Lewis, Unai Martinez-Corral, Peter Ladow, Peter Flake

Meeting Discussion

• DPI
  • Attribute EXPORT vs FOREIGN: it's ok to have two separate attributes, for making it explicit, albeit slightly redundant.
  • We agree that providing a standardized C header for defining fat pointers is desirable. However, we need feedback from vendors.
    • Unai will update https://github.com/umarcor/ghdl-cosim/blob/develop/vhpidirect/vffi_user.h, by including fat pointers for access types.
    • PeterFlake will look how SV handles these, as he (obviously) can not remember such specific details.
  • The FFI/DPI interface will NOT be part of VHPI, but a separate interface. However, data type conversions, specially of simple types, will be shared. That is, section 22.2 of the current LRM.
  • We discussed about variables of modes `out` or `inout` and about passing signals. These, along with supporting `wait` statements in foreign functions does require a further thought.
    • The first version might just not support either `wait` statements or signals, but only variables or constants. However, we should consider other features too, so we avoid future breaking changes.
  • PeterLadow proposed all symbols to be exported and imported automatically, through name mangling, as in C++.
    • That's related to https://umarcor.github.io/ghdl-cosim/vhdl202x/proposal-vffi.html#deferreddef and https://umarcor.github.io/ghdl-cosim/vhdl202x/proposal-vffi.html#function-overloading

Next Meeting

24 September 2020, 11 am Pacific Daylight Time (GMT-7)

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