From: Matt Mackall <mpm@selenic.com>
To: Andrew Morton <akpm@osdl.org>, "Theodore Ts'o" <tytso@mit.edu>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 10/12] random pt3: Simplify hash folding
Date: Wed, 19 Jan 2005 00:17:23 -0800 [thread overview]
Message-ID: <11.64403262@selenic.com> (raw)
In-Reply-To: <10.64403262@selenic.com>
Simplify output hash folding
Signed-off-by: Matt Mackall <mpm@selenic.com>
Index: rnd/drivers/char/random.c
===================================================================
--- rnd.orig/drivers/char/random.c 2005-01-18 10:42:17.993300522 -0800
+++ rnd/drivers/char/random.c 2005-01-18 10:42:39.078612373 -0800
@@ -1166,15 +1166,10 @@
* In case the hash function has some recognizable
* output pattern, we fold it in half.
*/
- for (i = 0; i < HASH_BUFFER_SIZE / 2; i++)
- buf[i] ^= buf[i + (HASH_BUFFER_SIZE + 1) / 2];
- if (HASH_BUFFER_SIZE & 1) {
- /* There's a middle word to deal with */
- x = buf[HASH_BUFFER_SIZE/2];
- x ^= (x >> 16); /* Fold it in half */
- ((__u16 *)buf)[HASH_BUFFER_SIZE - 1] = (__u16)x;
- }
+ buf[0] ^= buf[3];
+ buf[1] ^= buf[4];
+ buf[0] ^= rol32(buf[3], 16);
}
static ssize_t extract_entropy(struct entropy_store *r, void * buf,
next prev parent reply other threads:[~2005-01-19 8:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-19 8:17 [PATCH 0/12] random pt3: More core and accounting cleanups Matt Mackall
2005-01-19 8:17 ` [PATCH 1/12] random pt3: More meaningful pool names Matt Mackall
2005-01-19 8:17 ` [PATCH 2/12] random pt3: Static allocation of pools Matt Mackall
2005-01-19 8:17 ` [PATCH 3/12] random pt3: Static sysctl bits Matt Mackall
2005-01-19 8:17 ` [PATCH 4/12] random pt3: Catastrophic reseed checks Matt Mackall
2005-01-19 8:17 ` [PATCH 5/12] random pt3: Entropy reservation accounting Matt Mackall
2005-01-19 8:17 ` [PATCH 6/12] random pt3: Reservation flag in pool struct Matt Mackall
2005-01-19 8:17 ` [PATCH 7/12] random pt3: Reseed pointer " Matt Mackall
2005-01-19 8:17 ` [PATCH 8/12] random pt3: Break up extract_user Matt Mackall
2005-01-19 8:17 ` [PATCH 9/12] random pt3: Remove dead MD5 copy Matt Mackall
2005-01-19 8:17 ` Matt Mackall [this message]
2005-01-19 8:17 ` [PATCH 11/12] random pt3: Clean up hash buffering Matt Mackall
2005-01-19 8:17 ` [PATCH 12/12] random pt3: Remove entropy batching Matt Mackall
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