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86 lines
2.2 KiB
86 lines
2.2 KiB
//! Bytes related utils
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use libc::c_void;
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use std::{
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slice,
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mem,
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};
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/// Copy slice of bytes only. To copy generic slice, use `util::copy_slice()`.
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///
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/// # Notes
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/// `dst` and `src` must not overlap. See [move_slice].
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pub fn copy_slice(dst: &mut [u8], src: &[u8]) -> usize
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{
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let sz = std::cmp::min(dst.len(),src.len());
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unsafe {
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libc::memcpy(&mut dst[0] as *mut u8 as *mut c_void, &src[0] as *const u8 as *const c_void, sz);
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}
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sz
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}
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/// Move slice of bytes only
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///
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/// # Notes
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/// `dst` and `src` can overlap.
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pub fn move_slice(dst: &mut [u8], src: &[u8]) -> usize
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{
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let sz = std::cmp::min(dst.len(),src.len());
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unsafe {
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libc::memmove(&mut dst[0] as *mut u8 as *mut c_void, &src[0] as *const u8 as *const c_void, sz);
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}
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sz
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}
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/// Get the bytes of a value
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pub fn refer<T: ?Sized>(value: &T) -> &[u8]
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{
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unsafe {
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slice::from_raw_parts(value as *const T as *const u8, mem::size_of_val(value))
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}
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}
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/// Get a mutable reference of the bytes of a value
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pub fn refer_mut<T: ?Sized>(value: &mut T) -> &mut [u8]
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{
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unsafe {
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slice::from_raw_parts_mut(value as *mut T as *mut u8, mem::size_of_val(value))
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}
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}
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/// Get a type from its bytes
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///
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/// # Notes
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/// This function omits bounds checks in production builds
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pub unsafe fn derefer_unchecked<T>(bytes: &[u8]) -> *const T
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{
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#[cfg(debug_assertions)] assert!(bytes.len() >= mem::size_of::<T>(), "not enough bytes ");
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&bytes[0] as *const u8 as *const T
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}
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/// Get a mutable reference to a type from its bytes
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///
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/// # Notes
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/// This function omits bounds checks in production builds
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pub unsafe fn derefer_unchecked_mut<T>(bytes: &mut [u8]) -> *mut T
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{
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#[cfg(debug_assertions)] assert!(bytes.len() >= mem::size_of::<T>(), "not enough bytes ");
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&mut bytes[0] as *mut u8 as *mut T
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}
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/// Get a type from its bytes
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pub fn derefer<T>(bytes: &[u8]) -> *const T
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{
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assert!(bytes.len() >= mem::size_of::<T>(), "not enough bytes ");
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&bytes[0] as *const u8 as *const T
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}
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/// Get a mutable reference to a type from its bytes
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///
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/// # Notes
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/// This function omits bounds checks in production builds
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pub fn derefer_mut<T>(bytes: &mut [u8]) -> *mut T
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{
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assert!(bytes.len() >= mem::size_of::<T>(), "not enough bytes ");
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&mut bytes[0] as *mut u8 as *mut T
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}
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