Call C function writed in unstandard C

There is a function writed in C, and it's used as a device drive, so there is a header file included to specify the device. I try the legacy_code to call the function and want to generate_for_sim. Unfortunately, never success and the error is "unknown charater "0x40". Maybe this is because the VS don't know @ which is defined by Code Warrior

%header file

    struct {
      byte         :1;
      byte grpPSEL_1 :7;
    } MergedBits;
  } HPRIOSTR;
  extern volatile HPRIOSTR _HPRIO @(REG_BASE + 0x0000001FUL);