xref: /gem5/src/systemc/tests/systemc/bugs/sign_extension/sign_extension.cpp

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/*****************************************************************************

  sign_extension.cpp --

  Original Author: Philipp A. Hartmann, OFFIS, 2012-07-17

 -----------------------------------------------------------------------------

 This test demonatrates a bug in the sc_biguint constructor(?), where
 construction from bit-wise expressions with "unsigned int" and sc_bigint
 may lead to wrongly sign-extended values (at least on 32-bit machines) when
 the destination size is bigger than the source size.

 *****************************************************************************/

#include <systemc>
using sc_dt::sc_int;
using sc_dt::sc_uint;
using sc_dt::sc_bigint;
using sc_dt::sc_biguint;
using sc_dt::SC_BIN;

#define DUMP_VAR( Var ) \
  std::cout << #Var "=" << (Var).to_string(SC_BIN) << "\n"

int sc_main(int, char*[])
{

    sc_int<31>     v_sc_int_31_min     = (1<<30); // 010...0 (31 bit)
    sc_bigint<31>  v_sc_bigint_31_min  = (1<<30); // 010...0
    unsigned int   v_uint_max          = ~0;      // 11....1 (32-bit)
    sc_uint<32>    v_sc_uint32_max     = ~0;      // 11....1 (32-bit)
    sc_biguint<32> v_sc_biguint_32_max = -1;      // 11....1 (32-bit)

    DUMP_VAR( v_sc_int_31_min );
    DUMP_VAR( v_sc_bigint_31_min );
    DUMP_VAR( v_sc_uint32_max );
    DUMP_VAR( v_sc_biguint_32_max );

    sc_bigint<64> int31_uint         = (v_sc_int_31_min    & v_uint_max);
    // the following expression yields 0b1....10...0 on 32-bit machines
    sc_bigint<64> bigint31_uint      = (v_sc_bigint_31_min & v_uint_max);
    sc_bigint<64> bigint31_uint32    = (v_sc_bigint_31_min & v_sc_uint32_max);
    sc_bigint<64> bigint31_biguint32 = (v_sc_bigint_31_min & v_sc_biguint_32_max);

    DUMP_VAR( v_sc_bigint_31_min & v_uint_max );
    DUMP_VAR( v_sc_bigint_31_min & v_sc_biguint_32_max );

    DUMP_VAR(int31_uint);
    DUMP_VAR(bigint31_uint); // <--
    DUMP_VAR(bigint31_uint32);
    DUMP_VAR(bigint31_biguint32);

    return 0;
}