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crypto: sha512 - Use binary and instead of modulus

commit 58d7d18 upstream.

The previous patch used the modulus operator over a power of 2
unnecessarily which may produce suboptimal binary code.  This
patch changes changes them to binary ands instead.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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herbertx authored and gregkh committed Jan 26, 2012
1 parent 23cfecf commit f334f74575cb0d9463d39caf4a43483cfc3dd542
Showing with 2 additions and 2 deletions.
  1. +2 −2 crypto/sha512_generic.c
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@@ -78,7 +78,7 @@ static inline void LOAD_OP(int I, u64 *W, const u8 *input)
static inline void BLEND_OP(int I, u64 *W)
{
- W[I % 16] += s1(W[(I-2) % 16]) + W[(I-7) % 16] + s0(W[(I-15) % 16]);
+ W[I & 15] += s1(W[(I-2) & 15]) + W[(I-7) & 15] + s0(W[(I-15) & 15]);
}
static void
@@ -105,7 +105,7 @@ sha512_transform(u64 *state, const u8 *input)
#define SHA512_16_79(i, a, b, c, d, e, f, g, h) \
BLEND_OP(i, W); \
- t1 = h + e1(e) + Ch(e, f, g) + sha512_K[i] + W[(i)%16]; \
+ t1 = h + e1(e) + Ch(e, f, g) + sha512_K[i] + W[(i)&15]; \
t2 = e0(a) + Maj(a, b, c); \
d += t1; \
h = t1 + t2

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