From 427835d242aa1807d420ed05598cc3e655d6b2af Mon Sep 17 00:00:00 2001
From: Sunil Nimmagadda <sunil@nimmagadda.net>
Date: Thu, 5 Jan 2023 16:03:05 +0530
Subject: Note about avoiding mutability.

---
 src/vrrpv2.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/vrrpv2.rs b/src/vrrpv2.rs
index 0db2d7d..16bd74e 100644
--- a/src/vrrpv2.rs
+++ b/src/vrrpv2.rs
@@ -84,6 +84,12 @@ fn parse_auth_type(input: &[u8]) -> IResult<&[u8], VRRPv2AuthType> {
 // if let Some([b]) = chunks.remainder() {
 //     sum += *b as u32
 // }
+
+// Shadowing can be used to avoid `mut`...
+// let sum =...;
+// let sum = (sum & 0xffff) + (sum >> 16);
+// let sum = (sum & 0xffff) + (sum >> 16);
+// manually un-rolling while loop since it's needed atmost twice for an u32.
 fn validate_checksum(bytes: &[u8]) -> bool {
     let mut sum: u32 = bytes.chunks(2).fold(0, |acc: u32, x| {
         acc + u32::from(u16::from_ne_bytes(x.try_into().unwrap()))
-- 
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