Function pregexec 

pub unsafe fn pregexec(
    my_perl: *mut PerlInterpreter,
    a: *mut REGEXP,
    b: *mut c_char,
    c: *mut c_char,
    d: *mut c_char,
    e: isize,
    f: *mut SV,
    g: U32,
) -> I32

pregexec [THX] - macro function