[CRYPTO] sha1: Avoid shifting count left and right

This patch avoids shifting the count left and right needlessly for each
call to sha1_update().  It instead can be done only once at the end in
sha1_final().

Keeping the previous test example (sha1_update() successively called with
len=64), a 1.3% performance increase can be observed on i386, or 0.2% on
ARM.  The generated code is also smaller on ARM.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/sha1.c b/crypto/sha1.c
index 7b1abca293657340320f2f946f4f426d3b0355fe..8048e2dd3c14e3343a7efc78985e787c70466bca 100644 (file)
--- a/crypto/sha1.c
+++ b/crypto/sha1.c
@@ -52,8 +52,8 @@ static void sha1_update(void *ctx, const u8 *data, unsigned int len)
        unsigned int partial, done;
        const u8 *src;
 
-       partial = (sctx->count >> 3) & 0x3f;
-       sctx->count += len << 3;
+       partial = sctx->count & 0x3f;
+       sctx->count += len;
        done = 0;
        src = data;
 
@@ -88,10 +88,10 @@ static void sha1_final(void* ctx, u8 *out)
        __be64 bits;
        static const u8 padding[64] = { 0x80, };
 
-       bits = cpu_to_be64(sctx->count);
+       bits = cpu_to_be64(sctx->count << 3);
 
        /* Pad out to 56 mod 64 */
-       index = (sctx->count >> 3) & 0x3f;
+       index = sctx->count & 0x3f;
        padlen = (index < 56) ? (56 - index) : ((64+56) - index);
        sha1_update(sctx, padding, padlen);