| // Copyright 2024, The Android Open Source Project |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| /// The size of a 4KB memory in bytes. |
| pub const SIZE_4KB: usize = 4 << 10; |
| |
| #[cfg(target_arch = "aarch64")] |
| /// Computes the largest multiple of the provided alignment smaller or equal to the address. |
| /// |
| /// Note: the result is undefined if alignment isn't a power of two. |
| pub const fn unchecked_align_down(addr: usize, alignment: usize) -> usize { |
| addr & !(alignment - 1) |
| } |
| |
| #[cfg(target_arch = "aarch64")] |
| /// Computes the address of the 4KiB page containing a given address. |
| pub const fn page_4kb_of(addr: usize) -> usize { |
| unchecked_align_down(addr, SIZE_4KB) |
| } |
