[CRYPTO] sha1: Avoid useless memcpy()

The current code unconditionally copy the first block for every call to
sha1_update().  This can be avoided if there is no pending partial block.
This is always the case on the first call to sha1_update() (if the length
is >= 64 of course.

Furthermore, temp does need to be called if sha_transform is never invoked.
Also consolidate the sha_transform calls into one to reduce code size.

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

1 files changed, 17 insertions, 8 deletions

diff --git a/crypto/sha1.c b/crypto/sha1.c
index c686e7826174..292dcc13ff92 100644
--- a/crypto/sha1.c
+++ b/crypto/sha1.c
@@ -50,22 +50,31 @@ static void sha1_update(void *ctx, const u8 *data, unsigned int len)
 {
         struct sha1_ctx *sctx = ctx;
         unsigned int i, j;
-        u32 temp[SHA_WORKSPACE_WORDS];
+        const u8 *src;
 
         j = (sctx->count >> 3) & 0x3f;
         sctx->count += len << 3;
+        i = 0;
+        src = data;
 
         if ((j + len) > 63) {
-                memcpy(&sctx->buffer[j], data, (i = 64-j));
-                sha_transform(sctx->state, sctx->buffer, temp);
-                for ( ; i + 63 < len; i += 64) {
-                        sha_transform(sctx->state, &data[i], temp);
+                u32 temp[SHA_WORKSPACE_WORDS];
+
+                if (j) {
+                        memcpy(&sctx->buffer[j], data, (i = 64-j));
+                        src = sctx->buffer;
                 }
+
+                do {
+                        sha_transform(sctx->state, src, temp);
+                        i += 64;
+                        src = &data[i];
+                } while (i + 63 < len);
+
+                memset(temp, 0, sizeof(temp));
                 j = 0;
         }
-        else i = 0;
-        memset(temp, 0, sizeof(temp));
-        memcpy(&sctx->buffer[j], &data[i], len - i);
+        memcpy(&sctx->buffer[j], src, len - i);
 }