(
&self,
req_size: GuestUsize,
alignment: GuestUsize,
)
| 124 | } |
| 125 | |
| 126 | fn first_available_range( |
| 127 | &self, |
| 128 | req_size: GuestUsize, |
| 129 | alignment: GuestUsize, |
| 130 | ) -> Option<GuestAddress> { |
| 131 | let reversed_ranges: Vec<(&GuestAddress, &GuestUsize)> = self.ranges.iter().rev().collect(); |
| 132 | |
| 133 | for (idx, (address, _size)) in reversed_ranges.iter().enumerate() { |
| 134 | let next_range_idx = idx + 1; |
| 135 | let prev_end_address = if next_range_idx >= reversed_ranges.len() { |
| 136 | self.base |
| 137 | } else { |
| 138 | reversed_ranges[next_range_idx] |
| 139 | .0 |
| 140 | .unchecked_add(*(reversed_ranges[next_range_idx].1)) |
| 141 | }; |
| 142 | |
| 143 | // If we have enough space between this range and the previous one, |
| 144 | // we return the start of this range minus the requested size. |
| 145 | // As each new range is allocated at the end of the available address space, |
| 146 | // we will tend to always allocate new ranges there as well. In other words, |
| 147 | // ranges accumulate at the end of the address space. |
| 148 | if let Some(size_delta) = |
| 149 | address.checked_sub(self.align_address(prev_end_address, alignment).raw_value()) |
| 150 | { |
| 151 | let adjust = alignment.saturating_sub(1); |
| 152 | if size_delta.raw_value() >= req_size { |
| 153 | return Some( |
| 154 | self.align_address(address.unchecked_sub(req_size + adjust), alignment), |
| 155 | ); |
| 156 | } |
| 157 | } |
| 158 | } |
| 159 | |
| 160 | None |
| 161 | } |
| 162 | |
| 163 | /// Allocates a range of addresses from the managed region. Returns `Some(allocated_address)` |
| 164 | /// when successful, or `None` if an area of `size` can't be allocated or if alignment isn't |
no test coverage detected