chore: checkpoint before Python removal

vendor/ring/src/arithmetic.rs

@@ -0,0 +1,47 @@
+// Copyright 2017-2023 Brian Smith.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+pub(crate) use self::{constant::limbs_from_hex, limb_slice_error::LimbSliceError};
+use crate::{error::LenMismatchError, limb::LIMB_BITS};
+
+#[macro_use]
+mod ffi;
+
+mod constant;
+
+#[cfg(feature = "alloc")]
+pub mod bigint;
+
+pub(crate) mod inout;
+mod limbs;
+mod limbs512;
+pub mod montgomery;
+
+mod n0;
+
+// The minimum number of limbs allowed for any `&[Limb]` operation.
+//
+// TODO: Use `256 / LIMB_BITS` so that the limit is independent of limb size.
+pub const MIN_LIMBS: usize = 4;
+
+// The maximum number of limbs allowed for any `&[Limb]` operation.
+pub const MAX_LIMBS: usize = 8192 / LIMB_BITS;
+
+cold_exhaustive_error! {
+    enum limb_slice_error::LimbSliceError {
+        len_mismatch => LenMismatch(LenMismatchError),
+        too_short => TooShort(usize),
+        too_long => TooLong(usize),
+    }
+}