1 files changed, 37 insertions, 0 deletions
diff --git a/third_party/rust/sha2/src/sha256.rs b/third_party/rust/sha2/src/sha256.rs
new file mode 100644
index 0000000000..a45331e17a
--- /dev/null
+++ b/third_party/rust/sha2/src/sha256.rs
@@ -0,0 +1,37 @@
+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)
+}