Re: [PATCH 1/5] crypto/sha1.c: avoid useless memcpy()

[Herbert Xu]

On Sat, Nov 12, 2005 at 03:29:24PM -0500, Nicolas Pitre wrote:
> 
> Looks fine indeed.

Thanks.  I ended up moving src = data out of the if clause as well.
So this is what I committed in the end.

Cheers,
-- 
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0bca426e18e7626f8167bedecbd8118887d21c23
diff --git a/crypto/sha1.c b/crypto/sha1.c
--- a/crypto/sha1.c
+++ b/crypto/sha1.c
@@ -50,22 +50,31 @@ static void sha1_update(void *ctx, const
 {
        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);
 }
 
 

diff --git a/crypto/sha1.c b/crypto/sha1.c
--- a/crypto/sha1.c
+++ b/crypto/sha1.c
@@ -49,32 +49,33 @@ static void sha1_init(void *ctx)
 static void sha1_update(void *ctx, const u8 *data, unsigned int len)
 {
        struct sha1_ctx *sctx = ctx;
-       unsigned int i, j;
+       unsigned int partial, done;
        const u8 *src;
 
-       j = (sctx->count >> 3) & 0x3f;
+       partial = (sctx->count >> 3) & 0x3f;
        sctx->count += len << 3;
-       i = 0;
+       done = 0;
        src = data;
 
-       if ((j + len) > 63) {
+       if ((partial + len) > 63) {
                u32 temp[SHA_WORKSPACE_WORDS];
 
-               if (j) {
-                       memcpy(&sctx->buffer[j], data, (i = 64-j));
+               if (partial) {
+                       done = 64 - partial;
+                       memcpy(sctx->buffer + partial, data, done);
                        src = sctx->buffer;
                }
 
                do {
                        sha_transform(sctx->state, src, temp);
-                       i += 64;
-                       src = &data[i];
-               } while (i + 63 < len);
+                       done += 64;
+                       src = data + done;
+               } while (done + 63 < len);
 
                memset(temp, 0, sizeof(temp));
-               j = 0;
+               partial = 0;
        }
-       memcpy(&sctx->buffer[j], src, len - i);
+       memcpy(sctx->buffer + partial, src, len - done);
 }