linux-kernel - Re: [PATCH] Crypto: gf128mul : fixed a parentheses coding style issue

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Date:	Sun, 12 Oct 2014 16:01:25 -0700
From:	Joe Perches <joe@...ches.com>
To:	Mike Roocroft <mike.linux@...nternet.com>
Cc:	herbert@...dor.apana.org.au, davem@...emloft.net,
	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Crypto: gf128mul : fixed a parentheses coding style
 issue

On Sun, 2014-10-12 at 21:49 +0100, Mike Roocroft wrote:
> Fixed a coding style issue.
[]
> diff --git a/crypto/gf128mul.c b/crypto/gf128mul.c
[]
> @@ -97,7 +97,7 @@
>      the table above
>  */
>  
> -#define xx(p, q)	0x##p##q
> +#define xx(p, q)	(0x##p##q)
>  
>  #define xda_bbe(i) ( \
>  	(i & 0x80 ? xx(43, 80) : 0) ^ (i & 0x40 ? xx(21, c0) : 0) ^ \

I think that macro is pretty useless and nothing
but obfuscation now.

The comment above it doesn't seem useful either.

How about just removing and replacing the uses
like this?

---
 crypto/gf128mul.c | 27 ++++++++-------------------
 1 file changed, 8 insertions(+), 19 deletions(-)

diff --git a/crypto/gf128mul.c b/crypto/gf128mul.c
index 5276607..90cf17d 100644
--- a/crypto/gf128mul.c
+++ b/crypto/gf128mul.c
@@ -88,29 +88,18 @@
 	q(0xf8), q(0xf9), q(0xfa), q(0xfb), q(0xfc), q(0xfd), q(0xfe), q(0xff) \
 }
 
-/*	Given the value i in 0..255 as the byte overflow when a field element
-    in GHASH is multiplied by x^8, this function will return the values that
-    are generated in the lo 16-bit word of the field value by applying the
-    modular polynomial. The values lo_byte and hi_byte are returned via the
-    macro xp_fun(lo_byte, hi_byte) so that the values can be assembled into
-    memory as required by a suitable definition of this macro operating on
-    the table above
-*/
-
-#define xx(p, q)	0x##p##q
-
 #define xda_bbe(i) ( \
-	(i & 0x80 ? xx(43, 80) : 0) ^ (i & 0x40 ? xx(21, c0) : 0) ^ \
-	(i & 0x20 ? xx(10, e0) : 0) ^ (i & 0x10 ? xx(08, 70) : 0) ^ \
-	(i & 0x08 ? xx(04, 38) : 0) ^ (i & 0x04 ? xx(02, 1c) : 0) ^ \
-	(i & 0x02 ? xx(01, 0e) : 0) ^ (i & 0x01 ? xx(00, 87) : 0) \
+	(i & 0x80 ? 0x4380 : 0) ^ (i & 0x40 ? 0x21c0 : 0) ^ \
+	(i & 0x20 ? 0x10e0 : 0) ^ (i & 0x10 ? 0x0870 : 0) ^ \
+	(i & 0x08 ? 0x0438 : 0) ^ (i & 0x04 ? 0x021c : 0) ^ \
+	(i & 0x02 ? 0x010e : 0) ^ (i & 0x01 ? 0x0087 : 0) \
 )
 
 #define xda_lle(i) ( \
-	(i & 0x80 ? xx(e1, 00) : 0) ^ (i & 0x40 ? xx(70, 80) : 0) ^ \
-	(i & 0x20 ? xx(38, 40) : 0) ^ (i & 0x10 ? xx(1c, 20) : 0) ^ \
-	(i & 0x08 ? xx(0e, 10) : 0) ^ (i & 0x04 ? xx(07, 08) : 0) ^ \
-	(i & 0x02 ? xx(03, 84) : 0) ^ (i & 0x01 ? xx(01, c2) : 0) \
+	(i & 0x80 ? 0xe100 : 0) ^ (i & 0x40 ? 0x7080 : 0) ^ \
+	(i & 0x20 ? 0x3840 : 0) ^ (i & 0x10 ? 0x1c20 : 0) ^ \
+	(i & 0x08 ? 0x0e10 : 0) ^ (i & 0x04 ? 0x0708 : 0) ^ \
+	(i & 0x02 ? 0x0384 : 0) ^ (i & 0x01 ? 0x01c2 : 0) \
 )
 
 static const u16 gf128mul_table_lle[256] = gf128mul_dat(xda_lle);


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