src/afl-performance.c

/*
   Written in 2019 by David Blackman and Sebastiano Vigna (vigna@acm.org)

   To the extent possible under law, the author has dedicated all copyright
   and related and neighboring rights to this software to the public domain
   worldwide. This software is distributed without any warranty.

   See <http://creativecommons.org/publicdomain/zero/1.0/>.

   This is xoshiro256++ 1.0, one of our all-purpose, rock-solid generators.
   It has excellent (sub-ns) speed, a state (256 bits) that is large
   enough for any parallel application, and it passes all tests we are
   aware of.

   For generating just floating-point numbers, xoshiro256+ is even faster.

   The state must be seeded so that it is not everywhere zero. If you have
   a 64-bit seed, we suggest to seed a splitmix64 generator and use its
   output to fill s[].
*/

#include <stdint.h>
#include "afl-fuzz.h"
#include "types.h"

#define XXH_INLINE_ALL
#include "xxhash.h"
#undef XXH_INLINE_ALL

void rand_set_seed(afl_state_t *afl, s64 init_seed) {

  afl->init_seed = init_seed;
  afl->rand_seed[0] =
      hash64((u8 *)&afl->init_seed, sizeof(afl->init_seed), HASH_CONST);
  afl->rand_seed[1] = afl->rand_seed[0] ^ 0x1234567890abcdef;
  afl->rand_seed[2] = (afl->rand_seed[0] & 0x1234567890abcdef) ^
                      (afl->rand_seed[1] | 0xfedcba9876543210);

}

#define ROTL(d, lrot) ((d << (lrot)) | (d >> (8 * sizeof(d) - (lrot))))

#ifdef WORD_SIZE_64
// romuDuoJr
inline AFL_RAND_RETURN rand_next(afl_state_t *afl) {

  AFL_RAND_RETURN xp = afl->rand_seed[0];
  afl->rand_seed[0] = 15241094284759029579u * afl->rand_seed[1];
  afl->rand_seed[1] = afl->rand_seed[1] - xp;
  afl->rand_seed[1] = ROTL(afl->rand_seed[1], 27);
  return xp;

}

#else
// RomuTrio32
inline AFL_RAND_RETURN rand_next(afl_state_t *afl) {

  AFL_RAND_RETURN xp = afl->rand_seed[0], yp = afl->rand_seed[1],
                  zp = afl->rand_seed[2];
  afl->rand_seed[0] = 3323815723u * zp;
  afl->rand_seed[1] = yp - xp;
  afl->rand_seed[1] = ROTL(afl->rand_seed[1], 6);
  afl->rand_seed[2] = zp - yp;
  afl->rand_seed[2] = ROTL(afl->rand_seed[2], 22);
  return xp;

}

#endif

#undef ROTL

/* returns a double between 0.000000000 and 1.000000000 */

inline double rand_next_percent(afl_state_t *afl) {

  return (double)(((double)rand_next(afl)) / (double)0xffffffffffffffff);

}

/* we switch from afl's murmur implementation to xxh3 as it is 30% faster -
   and get 64 bit hashes instead of just 32 bit. Less collisions! :-) */

#ifdef _DEBUG
u32 hash32(u8 *key, u32 len, u32 seed) {

#else
inline u32 hash32(u8 *key, u32 len, u32 seed) {

#endif

  return (u32)XXH64(key, len, seed);

}

#ifdef _DEBUG
u64 hash64(u8 *key, u32 len, u64 seed) {

#else
inline u64 hash64(u8 *key, u32 len, u64 seed) {

#endif

  return XXH64(key, len, seed);

}