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#![cfg_attr(docsrs, feature(doc_cfg))]
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#![doc = include_str!("../README.md")]
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// @@ begin lint list maintained by maint/add_warning @@
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#![allow(renamed_and_removed_lints)] // @@REMOVE_WHEN(ci_arti_stable)
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#![allow(unknown_lints)] // @@REMOVE_WHEN(ci_arti_nightly)
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#![warn(missing_docs)]
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#![warn(noop_method_call)]
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#![warn(unreachable_pub)]
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#![warn(clippy::all)]
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#![deny(clippy::await_holding_lock)]
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#![deny(clippy::cargo_common_metadata)]
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#![deny(clippy::cast_lossless)]
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#![deny(clippy::checked_conversions)]
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#![warn(clippy::cognitive_complexity)]
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#![deny(clippy::debug_assert_with_mut_call)]
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#![deny(clippy::exhaustive_enums)]
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#![deny(clippy::exhaustive_structs)]
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#![deny(clippy::expl_impl_clone_on_copy)]
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#![deny(clippy::fallible_impl_from)]
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#![deny(clippy::implicit_clone)]
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#![deny(clippy::large_stack_arrays)]
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#![warn(clippy::manual_ok_or)]
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#![deny(clippy::missing_docs_in_private_items)]
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#![warn(clippy::needless_borrow)]
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#![warn(clippy::needless_pass_by_value)]
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#![warn(clippy::option_option)]
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#![deny(clippy::print_stderr)]
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#![deny(clippy::print_stdout)]
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#![warn(clippy::rc_buffer)]
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#![deny(clippy::ref_option_ref)]
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#![warn(clippy::semicolon_if_nothing_returned)]
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#![warn(clippy::trait_duplication_in_bounds)]
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#![deny(clippy::unchecked_time_subtraction)]
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#![deny(clippy::unnecessary_wraps)]
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#![warn(clippy::unseparated_literal_suffix)]
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#![deny(clippy::unwrap_used)]
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#![deny(clippy::mod_module_files)]
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#![allow(clippy::let_unit_value)] // This can reasonably be done for explicitness
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#![allow(clippy::uninlined_format_args)]
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#![allow(clippy::significant_drop_in_scrutinee)] // arti/-/merge_requests/588/#note_2812945
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#![allow(clippy::result_large_err)] // temporary workaround for arti#587
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#![allow(clippy::needless_raw_string_hashes)] // complained-about code is fine, often best
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#![allow(clippy::needless_lifetimes)] // See arti#1765
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#![allow(mismatched_lifetime_syntaxes)] // temporary workaround for arti#2060
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#![allow(clippy::collapsible_if)] // See arti#2342
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#![deny(clippy::unused_async)]
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//! <!-- @@ end lint list maintained by maint/add_warning @@ -->
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mod compiler;
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mod constraints;
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mod err;
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mod generator;
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mod program;
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mod rand;
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mod register;
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mod scheduler;
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mod siphash;
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use crate::compiler::{Architecture, Executable};
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use crate::program::Program;
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use rand_core::RngCore;
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pub use crate::err::{CompilerError, Error};
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pub use crate::rand::SipRand;
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pub use crate::siphash::SipState;
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/// Option for selecting a HashX runtime
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#[derive(Default, Debug, Copy, Clone, Eq, PartialEq)]
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#[non_exhaustive]
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pub enum RuntimeOption {
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    /// Choose the interpreted runtime, without trying the compiler at all.
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    InterpretOnly,
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    /// Choose the compiled runtime only, and fail if it experiences any errors.
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    CompileOnly,
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    /// Always try the compiler first but fall back to the interpreter on error.
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    /// (This is the default)
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    #[default]
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    TryCompile,
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}
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/// Effective HashX runtime for a constructed program
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#[derive(Debug, Copy, Clone, Eq, PartialEq)]
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#[non_exhaustive]
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pub enum Runtime {
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    /// The interpreted runtime is active.
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    Interpret,
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    /// The compiled runtime is active.
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    Compiled,
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}
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/// Pre-built hash program that can be rapidly computed with different inputs
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///
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/// The program and initial state representation are not specified in this
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/// public interface, but [`std::fmt::Debug`] can describe program internals.
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#[derive(Debug)]
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pub struct HashX {
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    /// Keys used to generate an initial register state from the hash input
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    ///
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    /// Half of the key material generated from seed bytes go into the random
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    /// program generator, and the other half are saved here for use in each
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    /// hash invocation.
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    register_key: SipState,
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    /// A prepared randomly generated hash program
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    ///
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    /// In compiled runtimes this will be executable code, and in the
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    /// interpreter it's a list of instructions. There is no stable API for
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    /// program information, but the Debug trait will list programs in either
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    /// format.
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    program: RuntimeProgram,
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}
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/// Combination of [`Runtime`] and the actual program info used by that runtime
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///
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/// All variants of [`RuntimeProgram`] use some kind of inner heap allocation
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/// to store the program data.
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#[derive(Debug)]
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enum RuntimeProgram {
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    /// Select the interpreted runtime, and hold a Program for it to run.
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    Interpret(Program),
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    /// Select the compiled runtime, and hold an executable code page.
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    Compiled(Executable),
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}
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impl HashX {
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    /// The maximum available output size for [`Self::hash_to_bytes()`]
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    pub const FULL_SIZE: usize = 32;
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    /// Generate a new hash function with the supplied seed.
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    pub fn new(seed: &[u8]) -> Result<Self, Error> {
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        HashXBuilder::new().build(seed)
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    }
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    /// Check which actual program runtime is in effect.
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    ///
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    /// By default we try to generate code at runtime to accelerate the hash
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    /// function, but we fall back to an interpreter if this fails. The compiler
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    /// can be disabled entirely using [`RuntimeOption::InterpretOnly`] and
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    /// [`HashXBuilder`].
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    pub fn runtime(&self) -> Runtime {
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        match &self.program {
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            RuntimeProgram::Interpret(_) => Runtime::Interpret,
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            RuntimeProgram::Compiled(_) => Runtime::Compiled,
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        }
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    }
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    /// Calculate the first 64-bit word of the hash, without converting to bytes.
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    pub fn hash_to_u64(&self, input: u64) -> u64 {
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        self.hash_to_regs(input).digest(self.register_key)[0]
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    }
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    /// Calculate the hash function at its full output width, returning a fixed
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    /// size byte array.
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    pub fn hash_to_bytes(&self, input: u64) -> [u8; Self::FULL_SIZE] {
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        let words = self.hash_to_regs(input).digest(self.register_key);
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        let mut bytes = [0_u8; Self::FULL_SIZE];
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        for word in 0..words.len() {
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            bytes[word * 8..(word + 1) * 8].copy_from_slice(&words[word].to_le_bytes());
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        }
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        bytes
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    }
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    /// Common setup for hashes with any output format
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    #[inline(always)]
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    fn hash_to_regs(&self, input: u64) -> register::RegisterFile {
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        let mut regs = register::RegisterFile::new(self.register_key, input);
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        match &self.program {
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            RuntimeProgram::Interpret(program) => program.interpret(&mut regs),
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            RuntimeProgram::Compiled(executable) => executable.invoke(&mut regs),
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        }
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        regs
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    }
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}
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/// Builder for creating [`HashX`] instances with custom settings
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#[derive(Default, Debug, Clone, Eq, PartialEq)]
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pub struct HashXBuilder {
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    /// Current runtime() setting for this builder
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    runtime: RuntimeOption,
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}
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impl HashXBuilder {
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    /// Create a new [`HashXBuilder`] with default settings.
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    ///
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    /// Immediately calling [`Self::build()`] would be equivalent to using
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    /// [`HashX::new()`].
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    pub fn new() -> Self {
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        Default::default()
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    }
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    /// Select a new [`RuntimeOption`].
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    pub fn runtime(&mut self, runtime: RuntimeOption) -> &mut Self {
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        self.runtime = runtime;
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        self
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    }
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    /// Build a [`HashX`] instance with a seed and the selected options.
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    pub fn build(&self, seed: &[u8]) -> Result<HashX, Error> {
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        let (key0, key1) = SipState::pair_from_seed(seed);
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        let mut rng = SipRand::new(key0);
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        self.build_from_rng(&mut rng, key1)
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    }
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    /// Build a [`HashX`] instance from an arbitrary [`RngCore`] and
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    /// a [`SipState`] key used for initializing the register file.
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    pub fn build_from_rng<R: RngCore>(
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        &self,
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        rng: &mut R,
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        register_key: SipState,
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    ) -> Result<HashX, Error> {
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        let program = Program::generate(rng)?;
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        self.build_from_program(program, register_key)
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    }
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    /// Build a [`HashX`] instance from an already-generated [`Program`] and
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    /// [`SipState`] key.
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    ///
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    /// The program is either stored as-is or compiled, depending on the current
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    /// [`RuntimeOption`]. Requires a program as well as a [`SipState`] to be
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    /// used for initializing the register file.
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    fn build_from_program(&self, program: Program, register_key: SipState) -> Result<HashX, Error> {
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        Ok(HashX {
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            register_key,
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            program: match self.runtime {
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                RuntimeOption::InterpretOnly => RuntimeProgram::Interpret(program),
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                RuntimeOption::CompileOnly => {
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                    RuntimeProgram::Compiled(Architecture::compile((&program).into())?)
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                }
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                RuntimeOption::TryCompile => match Architecture::compile((&program).into()) {
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                    Ok(exec) => RuntimeProgram::Compiled(exec),
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                    Err(_) => RuntimeProgram::Interpret(program),
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                },
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            },
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        })
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    }
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}