linux-kernel - [PATCH 08/17] lib/bch: Replace open-coded parity calculation with parity32()

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Message-Id: <20250223164217.2139331-9-visitorckw@gmail.com>
Date: Mon, 24 Feb 2025 00:42:08 +0800
From: Kuan-Wei Chiu <visitorckw@...il.com>
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	Kuan-Wei Chiu <visitorckw@...il.com>,
	Yu-Chun Lin <eleanor15x@...il.com>
Subject: [PATCH 08/17] lib/bch: Replace open-coded parity calculation with parity32()

Refactor parity calculations to use the standard parity32() helper.
This change eliminates redundant implementations and improves code
efficiency.

Co-developed-by: Yu-Chun Lin <eleanor15x@...il.com>
Signed-off-by: Yu-Chun Lin <eleanor15x@...il.com>
Signed-off-by: Kuan-Wei Chiu <visitorckw@...il.com>
---
 lib/bch.c | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/lib/bch.c b/lib/bch.c
index 1c0cb07cdfeb..769459749982 100644
--- a/lib/bch.c
+++ b/lib/bch.c
@@ -311,18 +311,6 @@ static inline int deg(unsigned int poly)
 	return fls(poly)-1;
 }
 
-static inline int parity(unsigned int x)
-{
-	/*
-	 * public domain code snippet, lifted from
-	 * http://www-graphics.stanford.edu/~seander/bithacks.html
-	 */
-	x ^= x >> 1;
-	x ^= x >> 2;
-	x = (x & 0x11111111U) * 0x11111111U;
-	return (x >> 28) & 1;
-}
-
 /* Galois field basic operations: multiply, divide, inverse, etc. */
 
 static inline unsigned int gf_mul(struct bch_control *bch, unsigned int a,
@@ -524,7 +512,7 @@ static int solve_linear_system(struct bch_control *bch, unsigned int *rows,
 		tmp = 0;
 		for (r = m-1; r >= 0; r--) {
 			mask = rows[r] & (tmp|1);
-			tmp |= parity(mask) << (m-r);
+			tmp |= parity32(mask) << (m-r);
 		}
 		sol[p] = tmp >> 1;
 	}
-- 
2.34.1