netdev - [PATCH net-next v3 1/3] net: hns3: refine the tcam key convert handle

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Date: Wed, 21 Jun 2023 20:33:07 +0800
From: Hao Lan <lanhao@...wei.com>
To: <netdev@...r.kernel.org>
CC: <yisen.zhuang@...wei.com>, <salil.mehta@...wei.com>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <richardcochran@...il.com>, <lanhao@...wei.com>,
	<wangpeiyang1@...wei.com>, <shenjian15@...wei.com>, <chenhao418@...wei.com>,
	<simon.horman@...igine.com>, <wangjie125@...wei.com>, <yuanjilin@...rlc.com>,
	<cai.huoqing@...ux.dev>, <xiujianfeng@...wei.com>
Subject: [PATCH net-next v3 1/3] net: hns3: refine the tcam key convert handle

From: Jian Shen <shenjian15@...wei.com>

The result of expression '(k ^ ~v)  & k' is exactly
the same with  'k & v', so simplify it.
(k ^ ~v) & k == k & v
The truth table (in non table form):
k == 0, v == 0:
  (k ^ ~v) & k == (0 ^ ~0) & 0 == (0 ^ 1) & 0 == 1 & 0 == 0
  k & v == 0 & 0 == 0

k == 0, v == 1:
  (k ^ ~v) & k == (0 ^ ~1) & 0 == (0 ^ 0) & 0 == 1 & 0 == 0
  k & v == 0 & 1 == 0

k == 1, v == 0:
  (k ^ ~v) & k == (1 ^ ~0) & 1 == (1 ^ 1) & 1 == 0 & 1 == 0
  k & v == 1 & 0 == 0

k == 1, v == 1:
  (k ^ ~v) & k == (1 ^ ~1) & 1 == (1 ^ 0) & 1 == 1 & 1 == 1
  k & v == 1 & 1 == 1
Signed-off-by: Jian Shen <shenjian15@...wei.com>
Signed-off-by: Hao Lan <lanhao@...wei.com>
---
ChangeLog:
v1->v2:
Fixed the comment description error and added
the truth table in the comment.
suggested by Simon Horman.
---
 .../net/ethernet/hisilicon/hns3/hns3pf/hclge_main.h   | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.h b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.h
index 81aa6b0facf5..6a43d1515585 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.h
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.h
@@ -835,15 +835,10 @@ struct hclge_vf_vlan_cfg {
  * Then for input key(k) and mask(v), we can calculate the value by
  * the formulae:
  *	x = (~k) & v
- *	y = (k ^ ~v) & k
+ *	y = k & v
  */
-#define calc_x(x, k, v) (x = ~(k) & (v))
-#define calc_y(y, k, v) \
-	do { \
-		const typeof(k) _k_ = (k); \
-		const typeof(v) _v_ = (v); \
-		(y) = (_k_ ^ ~_v_) & (_k_); \
-	} while (0)
+#define calc_x(x, k, v) ((x) = ~(k) & (v))
+#define calc_y(y, k, v) ((y) = (k) & (v))
 
 #define HCLGE_MAC_STATS_FIELD_OFF(f) (offsetof(struct hclge_mac_stats, f))
 #define HCLGE_STATS_READ(p, offset) (*(u64 *)((u8 *)(p) + (offset)))
-- 
2.30.0