diff options
author | Chris Zankel | 2014-02-24 00:34:36 -0800 |
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committer | Chris Zankel | 2014-02-24 00:34:36 -0800 |
commit | b3fdfc1b4b641d372e35ced98814289bc60bc5d1 (patch) | |
tree | 5f11d5ba885031dde45690745646519fb887f447 /include/linux/random.h | |
parent | c0e50d41126e4786d9cf1105bdf783e55c99f915 (diff) | |
parent | f63b6d7555cd4064554b39da4d44c4cbbc9d6a4a (diff) |
Merge tag 'xtensa-for-next-20140221-1' into for_next
Xtensa fixes for 3.14:
- allow booting xtfpga on boards with new uBoot and >128MBytes memory;
- drop nonexistent GPIO32 support from fsf variant;
- don't select USE_GENERIC_SMP_HELPERS;
- enable common clock framework support, set up ethoc clock on xtfpga;
- wire up sched_setattr and sched_getattr syscalls.
Signed-off-by: Chris Zankel <chris@zankel.net>
Diffstat (limited to 'include/linux/random.h')
-rw-r--r-- | include/linux/random.h | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/include/linux/random.h b/include/linux/random.h index 4002b3df4c85..1cfce0e24dbd 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -8,7 +8,6 @@ #include <uapi/linux/random.h> - extern void add_device_randomness(const void *, unsigned int); extern void add_input_randomness(unsigned int type, unsigned int code, unsigned int value); @@ -38,6 +37,23 @@ struct rnd_state { u32 prandom_u32_state(struct rnd_state *state); void prandom_bytes_state(struct rnd_state *state, void *buf, int nbytes); +/** + * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro) + * @ep_ro: right open interval endpoint + * + * Returns a pseudo-random number that is in interval [0, ep_ro). Note + * that the result depends on PRNG being well distributed in [0, ~0U] + * u32 space. Here we use maximally equidistributed combined Tausworthe + * generator, that is, prandom_u32(). This is useful when requesting a + * random index of an array containing ep_ro elements, for example. + * + * Returns: pseudo-random number in interval [0, ep_ro) + */ +static inline u32 prandom_u32_max(u32 ep_ro) +{ + return (u32)(((u64) prandom_u32() * ep_ro) >> 32); +} + /* * Handle minimum values for seeds */ |