[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>

[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>
Nicolas Pitre · David S. Miller
1 parent c8a19c91b5
Showing 1 changed file with 17 additions and 8 deletions Side-by-side Diff
crypto/sha1.c
@@ -50,22 +50,31 @@
 {
 	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);
 }
...	...	@@ -50,22 +50,31 @@
50	50	{
51	51	struct sha1_ctx *sctx = ctx;
52	52	unsigned int i, j;
53		- u32 temp[SHA_WORKSPACE_WORDS];
	53	+ const u8 *src;
54	54
55	55	j = (sctx->count >> 3) & 0x3f;
56	56	sctx->count += len << 3;
	57	+ i = 0;
	58	+ src = data;
57	59
58	60	if ((j + len) > 63) {
59		- memcpy(&sctx->buffer[j], data, (i = 64-j));
60		- sha_transform(sctx->state, sctx->buffer, temp);
61		- for ( ; i + 63 < len; i += 64) {
62		- sha_transform(sctx->state, &data[i], temp);
	61	+ u32 temp[SHA_WORKSPACE_WORDS];
	62	+
	63	+ if (j) {
	64	+ memcpy(&sctx->buffer[j], data, (i = 64-j));
	65	+ src = sctx->buffer;
63	66	}
	67	+
	68	+ do {
	69	+ sha_transform(sctx->state, src, temp);
	70	+ i += 64;
	71	+ src = &data[i];
	72	+ } while (i + 63 < len);
	73	+
	74	+ memset(temp, 0, sizeof(temp));
64	75	j = 0;
65	76	}
66		- else i = 0;
67		- memset(temp, 0, sizeof(temp));
68		- memcpy(&sctx->buffer[j], &data[i], len - i);
	77	+ memcpy(&sctx->buffer[j], src, len - i);
69	78	}
70	79
71	80