45 lines
1.4 KiB
Rust
45 lines
1.4 KiB
Rust
#![allow(dead_code)]
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use core::mem;
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const SRAM_LOWER: usize = 0x2000_0000;
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const SRAM_UPPER: usize = 0x3000_0000;
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// #![feature(const_slice_ptr_len)]
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// https://github.com/rust-lang/rust/issues/71146
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pub(crate) fn slice_ptr_len<T>(ptr: *const [T]) -> usize {
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use core::ptr::NonNull;
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let ptr = ptr.cast_mut();
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if let Some(ptr) = NonNull::new(ptr) {
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ptr.len()
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} else {
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// We know ptr is null, so we know ptr.wrapping_byte_add(1) is not null.
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NonNull::new(ptr.wrapping_byte_add(1)).unwrap().len()
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}
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}
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// TODO: replace transmutes with core::ptr::metadata once it's stable
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pub(crate) fn slice_ptr_parts<T>(slice: *const [T]) -> (*const T, usize) {
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unsafe { mem::transmute(slice) }
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}
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pub(crate) fn slice_ptr_parts_mut<T>(slice: *mut [T]) -> (*mut T, usize) {
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unsafe { mem::transmute(slice) }
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}
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/// Does this slice reside entirely within RAM?
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pub(crate) fn slice_in_ram<T>(slice: *const [T]) -> bool {
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let (ptr, len) = slice_ptr_parts(slice);
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let ptr = ptr as usize;
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ptr >= SRAM_LOWER && (ptr + len * core::mem::size_of::<T>()) < SRAM_UPPER
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}
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/// Return an error if slice is not in RAM. Skips check if slice is zero-length.
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pub(crate) fn slice_in_ram_or<T, E>(slice: *const [T], err: E) -> Result<(), E> {
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let (_, len) = slice_ptr_parts(slice);
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if len == 0 || slice_in_ram(slice) {
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Ok(())
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} else {
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Err(err)
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}
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}
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