From: Matt Mackall <mpm@selenic.com>
Remove incorrectly named ln (it's log2!) and x86 asm function and replace with
fls bitop.
Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/drivers/char/random.c | 48 ------------------------------------------
1 files changed, 1 insertion(+), 47 deletions(-)
diff -puN drivers/char/random.c~random-pt2-kill-misnamed-log2 drivers/char/random.c
--- 25/drivers/char/random.c~random-pt2-kill-misnamed-log2 2005-01-16 00:53:38.426167224 -0800
+++ 25-akpm/drivers/char/random.c 2005-01-16 00:53:38.432166312 -0800
@@ -395,54 +395,11 @@ static DECLARE_WAIT_QUEUE_HEAD(random_wr
static void sysctl_init_random(struct entropy_store *random_state);
#endif
-/*****************************************************************
- *
- * Utility functions, with some ASM defined functions for speed
- * purposes
- *
- *****************************************************************/
static inline __u32 rol32(__u32 word, int shift)
{
return (word << shift) | (word >> (32 - shift));
}
-/*
- * More asm magic....
- *
- * For entropy estimation, we need to do an integral base 2
- * logarithm.
- *
- * Note the "12bits" suffix - this is used for numbers between
- * 0 and 4095 only. This allows a few shortcuts.
- */
-#if 0 /* Slow but clear version */
-static inline __u32 int_ln_12bits(__u32 word)
-{
- __u32 nbits = 0;
-
- while (word >>= 1)
- nbits++;
- return nbits;
-}
-#else /* Faster (more clever) version, courtesy Colin Plumb */
-static inline __u32 int_ln_12bits(__u32 word)
-{
- /* Smear msbit right to make an n-bit mask */
- word |= word >> 8;
- word |= word >> 4;
- word |= word >> 2;
- word |= word >> 1;
- /* Remove one bit to make this a logarithm */
- word >>= 1;
- /* Count the bits set in the word */
- word -= (word >> 1) & 0x555;
- word = (word & 0x333) + ((word >> 2) & 0x333);
- word += (word >> 4);
- word += (word >> 8);
- return word & 15;
-}
-#endif
-
#if 0
static int debug = 0;
module_param(debug, bool, 0644);
@@ -808,10 +765,7 @@ static void add_timer_randomness(struct
* Round down by 1 bit on general principles,
* and limit entropy entimate to 12 bits.
*/
- delta >>= 1;
- delta &= (1 << 12) - 1;
-
- entropy = int_ln_12bits(delta);
+ entropy = min_t(int, fls(delta>>1), 11);
}
/*
_