[CRYPTO] sha1: Avoid shifting count left and right (fa9b98fd) · Commits · e / devices / android_kernel_teracube_2e

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>

crypto/sha1.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -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);