71 lines
1.6 KiB
Rust
71 lines
1.6 KiB
Rust
/// Memcpy
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///
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/// Copy N bytes of memory from one location to another.
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#[no_mangle]
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pub unsafe extern fn memcpy(dest: *mut u8, src: *const u8,
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n: usize) -> *mut u8 {
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let mut i = 0;
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while i < n {
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*((dest as usize + i) as *mut u8) = *((src as usize + i) as *const u8);
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i += 1;
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}
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dest
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}
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/// Memmove
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///
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/// Copy N bytes of memory from src to dest. The memory areas may overlap.
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#[no_mangle]
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pub unsafe extern fn memmove(dest: *mut u8, src: *const u8,
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n: usize) -> *mut u8 {
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if src < dest as *const u8 {
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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 as usize + i) as *mut u8) = *((src as usize + i) as *const u8);
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}
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} else {
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let mut i = 0;
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while i < n {
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*((dest as usize + i) as *mut u8) = *((src as usize + i) as *const u8);
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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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/// Memset
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///
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/// Fill a block of memory with a specified value.
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#[no_mangle]
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pub unsafe extern fn memset(dest: *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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*((dest as usize + i) as *mut u8) = c as u8;
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i += 1;
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}
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dest
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}
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/// Memcmp
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///
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/// Compare two blocks of memory.
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#[no_mangle]
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pub unsafe extern 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 as usize + i) as *const u8);
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let b = *((s2 as usize + i) as *const u8);
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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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