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# aarch64-cpu
Low level access to processors using the AArch64 execution state.
This project is developed and maintained by the [Cortex-A team][team].
## [Documentation](https://docs.rs/aarch64-cpu)
## Minimum Supported Rust Version (MSRV)
This crate is guaranteed to compile on current stable Rust.
It might compile with older versions but that may change in any new patch release.
## Usage
Please note that for using this crate's [register definitions](src/registers) (as provided by
`aarch64_cpu::registers::*`), you need to also import
`aarch64_cpu::registers::{Readable, Writeable}`.
### Example
Check out https://github.com/rust-embedded/rust-raspberrypi-OS-tutorials for usage examples. Listed
below is a snippet of `rust-raspberrypi-OS-tutorials`'s early boot code.
```rust
use aarch64_cpu::{asm, registers::*};
// Some parts omitted for brevity.
unsafe fn prepare_el2_to_el1_transition(
virt_boot_core_stack_end_exclusive_addr: u64,
virt_kernel_init_addr: u64,
) {
// Enable timer counter registers for EL1.
CNTHCTL_EL2.write(CNTHCTL_EL2::EL1PCEN::SET + CNTHCTL_EL2::EL1PCTEN::SET);
// No offset for reading the counters.
CNTVOFF_EL2.set(0);
// Set EL1 execution state to AArch64.
HCR_EL2.write(HCR_EL2::RW::EL1IsAarch64);
// Set up a simulated exception return.
SPSR_EL2.write(
SPSR_EL2::D::Masked
+ SPSR_EL2::A::Masked
+ SPSR_EL2::I::Masked
+ SPSR_EL2::F::Masked
+ SPSR_EL2::M::EL1h,
);
}
```
## Disclaimer
Descriptive comments in the source files are taken from the
[ARM Architecture Reference Manual ARMv8, for ARMv8-A architecture profile](https://documentation-service.arm.com/static/62ff43b0e95b0a633aff8a64?token=).
## License
Licensed under either of
- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
http://www.apache.org/licenses/LICENSE-2.0)
- MIT License ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
at your option.
### Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the
work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any
additional terms or conditions.
## Code of Conduct
Contribution to this crate is organized under the terms of the [Rust Code of
Conduct][CoC], the maintainer of this crate, the [Cortex-A team][team], promises
to intervene to uphold that code of conduct.
[CoC]: CODE_OF_CONDUCT.md
[team]: https://github.com/rust-embedded/wg#the-cortex-a-team