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Change-Id: I6a6a69640e8a301a692a5455d1261816280d9cde

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diff --git a/crates/core/src/hive/skipfield.rs b/crates/core/src/hive/skipfield.rs
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+++ b/crates/core/src/hive/skipfield.rs
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+//! An implementation of a trait describing valid skipfield integer types.
+//!
+//! Only `u16`s and `u8`s are supported by default. However, other integral
+//! types may be used by implementing this trait on them; the trait is not
+//! sealed.
+
+use core::ops::{Add, AddAssign, Sub, SubAssign};
+
+/// Trait describing integral types in a generic way suitable for use as the
+/// element type of a skipfield.
+pub trait SkipfieldType:
+    Add + AddAssign + Sub + SubAssign + Ord + PartialOrd + Copy + Sized
+{
+    /// The maximum attainable value of this type.
+    const MAXIMUM: Self;
+
+    /// The zero element of this type.
+    const ZERO: Self;
+
+    /// The one element of this type.
+    const ONE: Self;
+
+    /// Conversion method from `usize` using `as` or an equivalent
+    fn from_usize(u: usize) -> Self;
+
+    /// Conversion method from `isize` using `as` or an equivalent
+    fn from_isize(i: isize) -> Self;
+}
+
+impl SkipfieldType for u16 {
+    const MAXIMUM: Self = u16::MAX;
+    const ZERO: Self = 0;
+    const ONE: Self = 1;
+
+    #[inline(always)]
+    fn from_usize(u: usize) -> Self {
+        u as u16
+    }
+
+    #[inline(always)]
+    fn from_isize(i: isize) -> Self {
+        i as u16
+    }
+}
+
+impl SkipfieldType for u8 {
+    const MAXIMUM: Self = u8::MAX;
+    const ZERO: Self = 0;
+    const ONE: Self = 1;
+
+    #[inline(always)]
+    fn from_usize(u: usize) -> Self {
+        u as u8
+    }
+
+    #[inline(always)]
+    fn from_isize(i: isize) -> Self {
+        i as u8
+    }
+}