Foreign Language Interface

[lemmuh]

I heavily use the Foreign Language Interface (FLI) in Modelsim to generate my own signals and processes for my verification. In fact I am writing my testbenches in the OO language Ruby which interacts with the Modelsim simulation kernel via the FLI.

Is it in nvc possible to generate my own signals and processes after the elaboration is done ?

[nickg]

Currently you can use VHPI to read or update signals but I haven't implemented the vhpi_create function yet which would allow you to create new signals. The existing VHPI support is just the minimum that was required to support cocotb, but I am actively working on improving it. AFAIK the capabilities of VHPI and FLI are fairly similar. Have you got some publicly available code samples?

[lemmuh]

Of what kind of code sample do you think ?

This is a list of FLI functions I use via the Ruby FFI (Foreign-Function-Interface) extension:

[:mti_GetRegionKind,           [:pointer],                                           :int    ],
[:mti_GetProcessRegion,        [:pointer],                                           :pointer],
[:mti_GetProcessName,          [:pointer],                                           :string ],
[:mti_GetCurrentRegion,        [],                                                   :pointer],
[:mti_GetCallingRegion,        [],                                                   :pointer],
[:mti_GetGenericList,          [:pointer],                                           InterfaceListStruct.by_ref],
[:mti_CallStack,               [],                                                   :int    ],
[:mti_Now,                     [],                                                   :uint   ],
[:mti_NowFormatted,            [:uint],                                              :string ],
[:mti_NowUpper,                [],                                                   :uint   ],
[:mti_GetTopRegion,            [],                                                   :pointer],
[:mti_NextRegion,              [:pointer],                                           :pointer],
[:mti_HigherRegion,            [:pointer],                                           :pointer],
[:mti_FirstLowerRegion,        [:pointer],                                           :pointer],
[:mti_HigherRegion,            [:pointer],                                           :pointer],
[:mti_GetCurrentRegion,        [],                                                   :pointer],
[:mti_GetLibraryName,          [:pointer],                                           :string ],
[:mti_GetPrimaryName,          [:pointer],                                           :string ],
[:mti_GetSecondaryName,        [:pointer],                                           :string ],
[:mti_GetRegionName,           [:pointer],                                           :string ],
[:mti_GetRegionFullName,       [:pointer],                                           :string ],
[:mti_GetRegionSourceName,     [:pointer],                                           :string ],
[:mti_ScheduleWakeup,          [:pointer, :int],                                     :void   ],
[:mti_CreateArrayType,         [:int, :int, :pointer],                               :pointer],
[:mti_CreateScalarType,        [:int, :int],                                         :pointer],
[:mti_CreateEnumType,          [:int, :int, :pointer],                               :pointer],
[:mti_CreateRealType,          [],                                                   :pointer],
[:mti_CreateSignal,            [:string, :pointer, :pointer],                        :pointer],
[:mti_CreateDriver,            [:pointer],                                           :pointer],
[:mti_CreateRegion,            [:pointer, :string],                                  :pointer],
[:mti_CreateProcess,           [:string, :pointer, :pointer],                        :pointer],
[:mti_ScheduleDriver,          [:pointer, :int, :int, :int],                         :void   ],
[:mti_SetDriverOwner,          [:pointer, :pointer],                                 :void   ],
[:mti_Sensitize,               [:pointer, :pointer, :int],                           :void   ],
[:mti_GetSignalValue,          [:pointer],                                           :int    ],
[:mti_GetSignalValueIndirect,  [:pointer, :pointer],                                 :pointer],
[:mti_GetSignalName,           [:pointer],                                           :string ],
[:mti_GetSignalNameIndirect,   [:pointer, :pointer, :int],                           :string ],
[:mti_GetSignalRegion,         [:pointer],                                           :pointer],
[:mti_GetSignalMode,           [:pointer],                                           :int    ],
[:mti_GetSignalType,           [:pointer],                                           :pointer],
[:mti_FirstSignal,             [:pointer],                                           :pointer],
[:mti_NextSignal,              [],                                                   :pointer],
[:mti_GetResolutionLimit,      [],                                                   :int    ],
[:mti_GetTypeKind,             [:pointer],                                           :int    ],
[:mti_IsFirstInit,             [],                                                   :int    ],
[:mti_GetEnumValues,           [:pointer],                                           :pointer],
[:mti_IsForced,                [:pointer],   :pointer    ],                          
[:mti_ForceSignal,             [:pointer, :string, :int, :int, :int, :int],          :int    ],
[:mti_FindRegion,              [:string],                                            :pointer],
[:mti_FindSignal,              [:string],                                            :pointer],
[:mti_FindDriver,              [:pointer],                                           :pointer],
[:mti_ReleaseSignal,           [:pointer],                                           :int    ],
[:mti_TickLength,              [:pointer],                                           :int    ],
[:mti_GetSignalSubelements,    [:pointer, :pointer],                                 :pointer],
[:mti_GetDriverSubelements,    [:pointer, :pointer],                                 :pointer],
[:mti_FirstLowerRegion,        [:pointer],                                           :pointer],
[:mti_HigherRegion,            [:pointer],                                           :pointer],
[:mti_NextRegion,              [:pointer],                                           :pointer],
[:mti_Desensitize,             [:pointer],                                           :void   ],
[:mti_TickDir,                 [:pointer],                                           :int    ],
[:mti_TickLeft,                [:pointer],                                           :int    ],
[:mti_TickRight,               [:pointer],                                           :int    ],
[:mti_GetDriverNames,          [:pointer, :pointer],                                 :pointer],
[:mti_GetDriverValues,         [:pointer, :pointer],                                 :pointer],
[:mti_GetDrivingSignals,       [:string],                                            :pointer],
[:mti_GetNumRecordElements,    [:pointer],                                           :int    ],
[:mti_GetArrayElementType,     [:pointer],                                           :pointer],
[:mti_SetSignalValue,          [:pointer, :int],                                     :void   ],
[:mti_Command,                 [:string],                                            :void   ],     
[:mti_Cmd,                     [:string],                                            :void   ],     
[:mti_Break,                   [],                                                   :void   ],     
[:mti_GetArraySignalValue,     [:pointer, :pointer],                                 :pointer],
[:mti_PrintMessage,            [:string],                                            :void   ],
[:mti_PrintFormatted,          [:string],                                            :void   ],
[:mti_IsColdRestore,           [],                                                   :int    ],
[:mti_SignalIsResolved,        [:pointer],                                           :int    ],
[:mti_FindVar,                 [:string],                                            :pointer],
[:mti_NextVar,                 [],                                                   :pointer],
[:mti_FirstVarByRegion,        [:pointer],                                           :pointer],
[:mti_GetVarValue,             [:pointer],                                           :int],
[:mti_GetVarValueIndirect,     [:pointer, :pointer],                                 :pointer],
[:mti_GetArrayVarValue,        [:pointer, :pointer],                                 :pointer],
[:mti_GetVarName,              [:pointer],                                           :string],
[:mti_GetVarKind,              [:pointer],                                           :int],
[:mti_GetVarType,              [:pointer],                                           :pointer],

In #634 you mention the JIT extension. May this a way to achieve this ?

[nickg]

Of what kind of code sample do you think ?

A minimal working example that demonstrates the kind of functionality you need.

[lemmuh]

In a first step, I would need functions which generate signals

vhpi_create_enum(symbols)
vhpi_create_real()
vhpi_create_scalar(left, right)
vhpi_create_string(length)

vhpi_create_record(layout)

vhpi_create_array_of_type(left, right, <enum|real|scalar|string>)

and I would need a function which generates a process

vhpi_create_process(sensitivity_list, process_function)

[lemmuh]

Do you plan any effort on this ?

[nickg]

Not immediately. I'm still looking for a working example of implementing a foreign model with VHPI. Preferably one that has been tested with a commercial simulator like RiveraPRO. I tried asking on the VHDL Gitter channel but did find anything.