bjorn3
46 lines
1.2 KiB
Rust
46 lines
1.2 KiB
Rust
use std::alloc::{self, Layout};
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use std::ptr;
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use std::ptr::NonNull;
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pub struct OffscreenBuffer {
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ptr: NonNull<[u32]>,
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}
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impl OffscreenBuffer {
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#[inline]
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fn layout(len: usize) -> Layout {
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// optimizes to an integer mul
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Layout::array::<u32>(len).unwrap().align_to(4096).unwrap()
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}
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#[inline]
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pub fn new(len: usize) -> Self {
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let layout = Self::layout(len);
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let ptr = unsafe { alloc::alloc_zeroed(layout) };
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let ptr = ptr::slice_from_raw_parts_mut(ptr.cast(), len);
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let ptr = NonNull::new(ptr).unwrap_or_else(|| alloc::handle_alloc_error(layout));
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OffscreenBuffer { ptr }
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}
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pub fn ptr(&self) -> *mut u8 {
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self.ptr.as_ptr().cast::<u8>()
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}
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}
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impl Drop for OffscreenBuffer {
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fn drop(&mut self) {
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let layout = Self::layout(self.ptr.len());
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unsafe { alloc::dealloc(self.ptr.as_ptr().cast(), layout) };
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}
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}
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impl std::ops::Deref for OffscreenBuffer {
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type Target = [u32];
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fn deref(&self) -> &[u32] {
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unsafe { self.ptr.as_ref() }
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}
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}
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impl std::ops::DerefMut for OffscreenBuffer {
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fn deref_mut(&mut self) -> &mut [u32] {
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unsafe { self.ptr.as_mut() }
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}
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}
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