44 lines
1.3 KiB
Rust
44 lines
1.3 KiB
Rust
// This file is part of libfringe, a low-level green threading library.
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// Copyright (c) whitequark <whitequark@whitequark.org>
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// See the LICENSE file included in this distribution.
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use core::slice;
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use alloc::alloc::alloc;
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use alloc::boxed::Box;
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use core::alloc::Layout;
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use stack::Stack;
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/// OwnedStack holds a non-guarded, heap-allocated stack.
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#[derive(Debug)]
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pub struct OwnedStack(Box<[u8]>);
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impl OwnedStack {
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/// Allocates a new stack with exactly `size` accessible bytes and alignment appropriate
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/// for the current platform using the default Rust allocator.
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pub fn new(size: usize) -> OwnedStack {
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unsafe {
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let aligned_size = size & !(::STACK_ALIGNMENT - 1);
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let ptr = alloc(Layout::from_size_align_unchecked(
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aligned_size,
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::STACK_ALIGNMENT,
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));
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OwnedStack(Box::from_raw(slice::from_raw_parts_mut(ptr, aligned_size)))
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}
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}
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}
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unsafe impl Stack for OwnedStack {
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#[inline(always)]
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fn base(&self) -> *mut u8 {
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// The slice cannot wrap around the address space, so the conversion from usize
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// to isize will not wrap either.
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let len = self.0.len() as isize;
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unsafe { self.limit().offset(len) }
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}
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#[inline(always)]
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fn limit(&self) -> *mut u8 {
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self.0.as_ptr() as *mut u8
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}
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}
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