60 lines
1.4 KiB
Rust
60 lines
1.4 KiB
Rust
#[no_mangle]
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pub unsafe extern "C" fn memcpy(dest: *mut u8,
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src: *const u8,
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n: usize)
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-> *mut u8 {
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let mut i = 0;
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while i < n {
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*dest.offset(i as isize) = *src.offset(i as isize);
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i += 1;
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}
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dest
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}
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#[no_mangle]
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pub unsafe extern "C" fn memmove(dest: *mut u8,
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src: *const u8,
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n: usize)
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-> *mut u8 {
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if src < dest as *const u8 {
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// copy from end
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let mut i = n;
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while i != 0 {
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i -= 1;
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*dest.offset(i as isize) = *src.offset(i as isize);
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}
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} else {
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// copy from beginning
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let mut i = 0;
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while i < n {
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*dest.offset(i as isize) = *src.offset(i as isize);
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i += 1;
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}
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}
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dest
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}
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#[no_mangle]
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pub unsafe extern "C" fn memset(s: *mut u8, c: i32, n: usize) -> *mut u8 {
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let mut i = 0;
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while i < n {
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*s.offset(i as isize) = c as u8;
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i += 1;
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}
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s
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}
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#[no_mangle]
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pub unsafe extern "C" fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32 {
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let mut i = 0;
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while i < n {
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let a = *s1.offset(i as isize);
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let b = *s2.offset(i as isize);
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if a != b {
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return a as i32 - b as i32;
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}
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i += 1;
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}
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0
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}
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