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// Copyright 2024 RISC Zero, Inc.
//
// 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.

#![doc = include_str!("../README.md")]
#![no_std]
#![allow(unused_variables)]
#![deny(rustdoc::broken_intra_doc_links)]
#![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]

pub mod memory;
#[macro_use]
pub mod syscall;
#[cfg(all(feature = "export-getrandom", target_os = "zkvm"))]
mod getrandom;
#[cfg(all(feature = "export-libm", target_os = "zkvm"))]
mod libm_extern;
#[cfg(all(feature = "rust-runtime", target_os = "zkvm"))]
pub mod rust_rt;

/// Size of a zkVM machine word in bytes.
/// 4 bytes (i.e. 32 bits) as the zkVM is an implementation of the rv32im ISA.
pub const WORD_SIZE: usize = core::mem::size_of::<u32>();

/// Size of a zkVM memory page.
pub const PAGE_SIZE: usize = 1024;

/// Standard IO file descriptors for use with sys_read and sys_write.
pub mod fileno {
    pub const STDIN: u32 = 0;
    pub const STDOUT: u32 = 1;
    pub const STDERR: u32 = 2;
    pub const JOURNAL: u32 = 3;
}

/// Align address upwards.
///
/// Returns the smallest `x` with alignment `align` so that `x >= addr`.
///
/// `align` must be a power of 2.
pub const fn align_up(addr: usize, align: usize) -> usize {
    let mask = align - 1;
    (addr + mask) & !mask
}