Verilator

The following import statement has a problem.

import "DPI-C" task CMRead64(input int regnum, input int address, output bit [63:0] rdata);

It converts to the following code in Vtb.cpp:

void Vtb::__Vdpiimwrap_v__DOT__GDPI__DOT__CMRead64_TOP(IData regnum, IData address, QData& rdata) {
    VL_DEBUG_IF(VL_PRINTF("    Vtb::__Vdpiimwrap_v__DOT__GDPI__DOT__CMRead64_TOP\n"); );
    // Body
    int regnum__Vcvt;
    regnum__Vcvt = regnum;
    int address__Vcvt;
    address__Vcvt = address;
    svBitVecVal rdata__Vcvt [2];
    CMRead64(regnum__Vcvt, address__Vcvt, rdata__Vcvt);
    rdata = rdata__Vcvt;
}

The code declares rdata as “QData&”, and then at the bottom does “rdata = rdata__Vcvt”. This assignment is illegal since “rdata__Vcvt” is a pointer to an array of ints, not an immediate 64-bit value (long unsigned int).

I think the coding should be similar to the following:

void Vtb::__Vdpiimwrap_v__DOT__GDPI__DOT__CMRead64_TOP(IData regnum, IData address, WData (& rdata)[2]) {
    VL_DEBUG_IF(VL_PRINTF("    Vtb::__Vdpiimwrap_v__DOT__GDPI__DOT__CMRead64_TOP\n"); );
    // Body
    int regnum__Vcvt;
    regnum__Vcvt = regnum;
    int address__Vcvt;
    address__Vcvt = address;
    svBitVecVal rdata__Vcvt [2];
    CMRead64(regnum__Vcvt, address__Vcvt, rdata__Vcvt);
    VL_ASSIGN_W(64,rdata, rdata__Vcvt);
}