51 lines
1.2 KiB
Rust
51 lines
1.2 KiB
Rust
use crate::constants::PAGE_SIZE;
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use crate::errors::VmError;
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use crate::util::align_up;
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#[derive(Debug, Clone)]
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pub struct Allocator {
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base: u64,
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size: u64,
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offset: u64,
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}
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impl Allocator {
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pub fn new(base: u64, size: u64) -> Self {
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Self {
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base,
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size,
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offset: 0,
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}
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}
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pub fn alloc(&mut self, request: u64) -> Result<u64, VmError> {
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let length = align_up(request.max(1), PAGE_SIZE);
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let address = self.base + self.offset;
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let next = self.offset.saturating_add(length);
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if next > self.size {
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return Err(VmError::AllocatorOom {
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base: self.base,
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size: self.size,
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request,
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});
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}
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self.offset = next;
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Ok(address)
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}
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}
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#[cfg(test)]
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mod tests {
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use super::Allocator;
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#[test]
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fn allocator_aligns_to_pages() {
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let mut allocator = Allocator::new(0x1000_0000, 0x20_000);
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let a = allocator.alloc(1).expect("alloc 1");
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let b = allocator.alloc(0x1500).expect("alloc 2");
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assert_eq!(a, 0x1000_0000);
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assert_eq!(b, 0x1000_1000);
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}
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}
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