View Compilation Error

0_0_33237554_23670.cpp: In member function 'int MI::get()':
0_0_33237554_23670.cpp:23:53: error: 'fread_unlocked' was not declared in this scope
 I(bs==be,be=(bs=bb)+fread_unlocked(bb,1,sizeof(bb),f))L*bs++;
                                                     ^
0_0_33237554_23670.cpp:13:20: note: in definition of macro 'I'
 #define I(c,a)if(c)a;
                    ^