1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66

#[allow(warnings)]
#[cfg(target_pointer_width = "16")]
type c_int = i16;
#[allow(warnings)]
#[cfg(not(target_pointer_width = "16"))]
type c_int = i32;

#[cfg_attr(all(feature = "mem", not(feature = "mangled-names")), no_mangle)]
pub unsafe extern "C" fn memcpy(dest: *mut u8,
                                src: *const u8,
                                n: usize)
                                -> *mut u8 {
    let mut i = 0;
    while i < n {
        *dest.offset(i as isize) = *src.offset(i as isize);
        i += 1;
    }
    dest
}

#[cfg_attr(all(feature = "mem", not(feature = "mangled-names")), no_mangle)]
pub unsafe extern "C" fn memmove(dest: *mut u8,
                                 src: *const u8,
                                 n: usize)
                                 -> *mut u8 {
    if src < dest as *const u8 {
        // copy from end
        let mut i = n;
        while i != 0 {
            i -= 1;
            *dest.offset(i as isize) = *src.offset(i as isize);
        }
    } else {
        // copy from beginning
        let mut i = 0;
        while i < n {
            *dest.offset(i as isize) = *src.offset(i as isize);
            i += 1;
        }
    }
    dest
}

#[cfg_attr(all(feature = "mem", not(feature = "mangled-names")), no_mangle)]
pub unsafe extern "C" fn memset(s: *mut u8, c: c_int, n: usize) -> *mut u8 {
    let mut i = 0;
    while i < n {
        *s.offset(i as isize) = c as u8;
        i += 1;
    }
    s
}

#[cfg_attr(all(feature = "mem", not(feature = "mangled-names")), no_mangle)]
pub unsafe extern "C" fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32 {
    let mut i = 0;
    while i < n {
        let a = *s1.offset(i as isize);
        let b = *s2.offset(i as isize);
        if a != b {
            return a as i32 - b as i32;
        }
        i += 1;
    }
    0
}