From 43345001482039e56fcf66de93e9f694ba15a57f Mon Sep 17 00:00:00 2001
From: Tony Arcieri <bascule@gmail.com>
Date: Thu, 22 Oct 2026 21:42:07 -0600
Subject: [PATCH] ctutils: add citation for `bitborrow!`

It can also be found in Hacker's Delight
---
 ctutils/src/primitives.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ctutils/src/primitives.rs b/ctutils/src/primitives.rs
index f1060a57..431df4c2 100644
--- a/ctutils/src/primitives.rs
+++ b/ctutils/src/primitives.rs
@@ -19,6 +19,8 @@ macro_rules! bitle {
 }
 
 /// Outgoing borrow bit for a wrapping `x - y - borrow_in` result.
+///
+/// See "Hacker's Delight", 2nd edition, section 2-13 (Overflow detection)
 macro_rules! bitborrow {
     ($x:expr, $y:expr, $result:expr, $bits:expr) => {
         (((!$x) & $y) | (((!$x) | $y) & $result)) >> ($bits - 1)