Accellera SystemC实现是否错误地实现了to_long（）？

Question

Consider the following SystemC code:

#include <iostream>
#include "systemc.h"

using namespace std;

int
sc_main(int argc, char* argv[])
{
    sc_bv<3> foo;   
    operand_0 = "0d6";
    cout << foo.to_long() << endl; // prints -2
    return EXIT_SUCCESS;
}

This prints out -2 rather than 6 as I would have expected. The apparent reason for doing so would be that to_long() interprets the bit-vector 0b110 as signed. However, in IEEE Std 1666-2011 , it says in Section 7.2.9 referring to integer conversion functions such as to_long():

These member functions shall interpret the bits within a SystemC integer, 
fixed-point type or vector, or any part-select or concatenation thereof, 
as representing an unsigned binary value, with the exception of signed
integers and signed fixed-point types.

Do I misunderstand something or is the SystemC implementation from Accellera not adhering to the standard in this aspect?

Answer 1

I think you are correct, there does seems to be a discrepancy between the SystemC LRM ( IEEE Std 1666-2011 ) and the implementation.

If you want foo to be interpreted as an unsigned value, you must use to_ulong() :

#include <iostream>
#include <systemc>

using namespace std;

int sc_main(int argc, char* argv[]) {
    sc_bv<3> foo("0d6");
    cout << foo.to_long() << endl; // prints -2
    cout << foo.to_ulong() << endl; // prints 6
    return EXIT_SUCCESS;
}