From ef91bd59e2befdb4be7321593fe8dc8f1250080e Mon Sep 17 00:00:00 2001
From: Jeff Garzik <jeff@garzik.org>
Date: Wed, 2 Mar 2011 22:03:11 -0500
Subject: sha256_4way: skip last 3 rounds.

Pointed out by several people, including Raulo.
---
 sha256_4way.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sha256_4way.c b/sha256_4way.c
index 2c5afd8..742682f 100644
--- a/sha256_4way.c
+++ b/sha256_4way.c
@@ -452,12 +452,16 @@ static void DoubleBlockSHA256(const void* pin, void* pad, const void *pre, unsig
         SHA256ROUND(f, g, h, a, b, c, d, e, 59, w11);
         w12 = add4(SIGMA1_256(w10), w5, SIGMA0_256(w13), w12);
         SHA256ROUND(e, f, g, h, a, b, c, d, 60, w12);
+
+	/* Skip last 3-rounds; not necessary for H==0 */
+#if 0
         w13 = add4(SIGMA1_256(w11), w6, SIGMA0_256(w14), w13);
         SHA256ROUND(d, e, f, g, h, a, b, c, 61, w13);
         w14 = add4(SIGMA1_256(w12), w7, SIGMA0_256(w15), w14);
         SHA256ROUND(c, d, e, f, g, h, a, b, 62, w14);
         w15 = add4(SIGMA1_256(w13), w8, SIGMA0_256(w0), w15);
         SHA256ROUND(b, c, d, e, f, g, h, a, 63, w15);
+#endif
 
         /* store resulsts directly in thash */
 #define store_2(x,i)  \
-- 
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