[PATCH 3/7] block-sha1: make the 'ntohl()' part of the first SHA1 loop

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Aug 6, 2009, 15:18 UTC
Message-ID: <alpine.LFD.2.01.0908060816550.3390@localhost.localdomain>
In-Reply-To: <alpine.LFD.2.01.0908060815430.3390@localhost.localdomain>

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 5 Aug 2009 20:28:07 -0700
Subject: [PATCH 3/7] block-sha1: make the 'ntohl()' part of the first SHA1 loop

This helps a teeny bit. But what I -really- want to do is to avoid the whole 80-array loop, and do the xor updates as I go along..

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

This is a pretty trivial one, but it was the first stage to getting rid of the annoying 80-word array that not only wastes precious L1 cache, but that loop to initialize it was a noticeable cost.

 block-sha1/sha1.c |   28 ++++++++++++++++------------
 1 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/block-sha1/sha1.c b/block-sha1/sha1.c
index a45a3de..39a5bbb 100644
--- a/block-sha1/sha1.c
+++ b/block-sha1/sha1.c
@@ -100,27 +100,31 @@ static void blk_SHA1Block(blk_SHA_CTX *ctx, const unsigned int *data)
 	unsigned int A,B,C,D,E,TEMP;
 	unsigned int W[80];
 
-	for (t = 0; t < 16; t++)
-		W[t] = htonl(data[t]);
-
-	/* Unroll it? */
-	for (t = 16; t <= 79; t++)
-		W[t] = SHA_ROL(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16], 1);
-
 	A = ctx->H[0];
 	B = ctx->H[1];
 	C = ctx->H[2];
 	D = ctx->H[3];
 	E = ctx->H[4];
 
-#define T_0_19(t) \
+#define T_0_15(t) \
+	TEMP = htonl(data[t]); W[t] = TEMP; \
+	TEMP += SHA_ROL(A,5) + (((C^D)&B)^D)     + E + 0x5a827999; \
+	E = D; D = C; C = SHA_ROR(B, 2); B = A; A = TEMP; \
+
+	T_0_15( 0); T_0_15( 1); T_0_15( 2); T_0_15( 3); T_0_15( 4);
+	T_0_15( 5); T_0_15( 6); T_0_15( 7); T_0_15( 8); T_0_15( 9);
+	T_0_15(10); T_0_15(11); T_0_15(12); T_0_15(13); T_0_15(14);
+	T_0_15(15);
+
+	/* Unroll it? */
+	for (t = 16; t <= 79; t++)
+		W[t] = SHA_ROL(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16], 1);
+
+#define T_16_19(t) \
 	TEMP = SHA_ROL(A,5) + (((C^D)&B)^D)     + E + W[t] + 0x5a827999; \
 	E = D; D = C; C = SHA_ROR(B, 2); B = A; A = TEMP;
 
-	T_0_19( 0); T_0_19( 1); T_0_19( 2); T_0_19( 3); T_0_19( 4);
-	T_0_19( 5); T_0_19( 6); T_0_19( 7); T_0_19( 8); T_0_19( 9);
-	T_0_19(10); T_0_19(11); T_0_19(12); T_0_19(13); T_0_19(14);
-	T_0_19(15); T_0_19(16); T_0_19(17); T_0_19(18); T_0_19(19);
+	T_16_19(16); T_16_19(17); T_16_19(18); T_16_19(19);
 
 #define T_20_39(t) \
 	TEMP = SHA_ROL(A,5) + (B^C^D)           + E + W[t] + 0x6ed9eba1; \

-- 
1.6.4.31.g154b2.dirty