use digest::{generic_array::GenericArray, typenum::U64};

cfg_if::cfg_if! {

    if #[cfg(feature = "force-soft")] {

        mod soft;

        use soft::compress;

    } else if #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] {

        #[cfg(not(feature = "asm"))]

        mod soft;

        #[cfg(feature = "asm")]

        mod soft {

            pub(crate) use sha2_asm::compress256 as compress;

        }

        mod x86;

        use x86::compress;

    } else if #[cfg(all(feature = "asm", target_arch = "aarch64"))] {

        mod soft;

        mod aarch64;

        use aarch64::compress;

    } else {

        mod soft;

        use soft::compress;

    }

}

/// Raw SHA-256 compression function.

///

/// This is a low-level "hazmat" API which provides direct access to the core

/// functionality of SHA-256.

#[cfg_attr(docsrs, doc(cfg(feature = "compress")))]

pub fn compress256(state: &mut [u32; 8], blocks: &[GenericArray<u8, U64>]) {

    // SAFETY: GenericArray<u8, U64> and [u8; 64] have

    // exactly the same memory layout

    let p = blocks.as_ptr() as *const [u8; 64];

    let blocks = unsafe { core::slice::from_raw_parts(p, blocks.len()) };

    compress(state, blocks)

}