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random: eliminate redundant new_rotate variable

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- eliminate new_rotate
- move input_rotate masking
- simplify input_rotate update
- move input_rotate update to end of inner loop for readability

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matt Mackall 2008-04-29 01:03:02 -07:00 committed by Linus Torvalds
parent 433582093a
commit feee76972b
1 changed files with 10 additions and 12 deletions
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22
drivers/char/random.c
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@ -455,7 +455,7 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in,
0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5; unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5;
int new_rotate, input_rotate; int input_rotate;
int wordmask = r->poolinfo->poolwords - 1; int wordmask = r->poolinfo->poolwords - 1;
__u32 w, next_w; __u32 w, next_w;
unsigned long flags; unsigned long flags;
@ -474,20 +474,10 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in,
add_ptr = r->add_ptr; add_ptr = r->add_ptr;
while (nwords--) { while (nwords--) {
w = rol32(next_w, input_rotate); w = rol32(next_w, input_rotate & 31);
if (nwords > 0) if (nwords > 0)
next_w = *in++; next_w = *in++;
i = add_ptr = (add_ptr - 1) & wordmask; i = add_ptr = (add_ptr - 1) & wordmask;
/*
* Normally, we add 7 bits of rotation to the pool.
* At the beginning of the pool, add an extra 7 bits
* rotation, so that successive passes spread the
* input bits across the pool evenly.
*/
new_rotate = input_rotate + 14;
if (i)
new_rotate = input_rotate + 7;
input_rotate = new_rotate & 31;
/* XOR in the various taps */ /* XOR in the various taps */
w ^= r->pool[(i + tap1) & wordmask]; w ^= r->pool[(i + tap1) & wordmask];
@ -497,6 +487,14 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in,
w ^= r->pool[(i + tap5) & wordmask]; w ^= r->pool[(i + tap5) & wordmask];
w ^= r->pool[i]; w ^= r->pool[i];
r->pool[i] = (w >> 3) ^ twist_table[w & 7]; r->pool[i] = (w >> 3) ^ twist_table[w & 7];
/*
* Normally, we add 7 bits of rotation to the pool.
* At the beginning of the pool, add an extra 7 bits
* rotation, so that successive passes spread the
* input bits across the pool evenly.
*/
input_rotate += i ? 7 : 14;
} }
r->input_rotate = input_rotate; r->input_rotate = input_rotate;