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 <[email protected]>
Index: linux-2.6/crypto/sha1.c
===================================================================
--- linux-2.6.orig/crypto/sha1.c
+++ linux-2.6/crypto/sha1.c
@@ -51,8 +51,8 @@
unsigned int partial, done;
u32 temp[SHA_WORKSPACE_WORDS];
- partial = (sctx->count >> 3) & 0x3f;
- sctx->count += len << 3;
+ partial = sctx->count & 0x3f;
+ sctx->count += len;
done = 0;
if ((partial + len) > 63) {
@@ -80,7 +80,7 @@
u8 bits[8] = { 0, };
static const u8 padding[64] = { 0x80, };
- t = sctx->count;
+ t = sctx->count << 3;
bits[7] = 0xff & t; t>>=8;
bits[6] = 0xff & t; t>>=8;
bits[5] = 0xff & t; t>>=8;
@@ -91,7 +91,7 @@
bits[0] = 0xff & t;
/* 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);
-
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