vpp - Vector Packet Processing

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/* * Copyright (c) 2015 Cisco and/or its affiliates. * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /* Copyright (c) 2001, 2002, 2003 Eliot Dresselhaus Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #ifndef included_random_h #define included_random_h #include <vppinfra/clib.h> #include <vppinfra/vec.h> /* for vec_resize */ #include <vppinfra/format.h> /* for unformat_input_t */ /** \file Linear Congruential Random Number Generator This specific random number generator is described in "Numerical Recipes in C", 2nd edition, page 284. If you need random numbers with really excellent statistics, take a look at Chapter 7... By definition, a linear congruential random number generator is of the form: rand[i+1] = a*rand[i] + c (mod m) for specific values of (a,c,m). In this case, choose m = 2**32 and use the low-order 32-bits of the 64-bit product a*N[i]. Knuth suggests the use of a=1664525, H.W. Lewis has tested C=1013904223 extensively. This routine is reputedly as good as any 32-bit LCRN, and costs only a single multiply-add. Several variants: 32/64-bit, machine word width, f64 on the closed interval [0,1]. */ /** \brief 32-bit random number generator */ always_inline u32 random_u32 (u32 * seed) { *seed = (1664525 * *seed) + 1013904223; return *seed; } /* External test routine. */ int test_random_main (unformat_input_t * input); /** \brief Maximum value returned by random_u32() */ always_inline u32 random_u32_max (void) { return 0xffffffff; } #ifdef CLIB_UNIX #include <unistd.h> /* for getpid */ /** \brief Default random seed (unix/linux user-mode) */ always_inline uword random_default_seed (void) { return getpid (); } #endif #ifdef CLIB_LINUX_KERNEL #include <linux/sched.h> /* for jiffies */ /** \brief Default random seed (Linux kernel) */ always_inline uword random_default_seed (void) { return jiffies; } #endif #ifdef CLIB_STANDALONE extern u32 standalone_random_default_seed; always_inline u32 random_default_seed (void) { return standalone_random_default_seed; } #endif /** \brief 64-bit random number generator * Again, constants courtesy of Donald Knuth. * */ always_inline u64 random_u64 (u64 * seed) { *seed = 6364136223846793005ULL * *seed + 1442695040888963407ULL; return *seed; } /** \brief machine word size random number generator */ always_inline uword random_uword (u32 * seed) { if (sizeof (uword) == sizeof (u64)) return random_u64 ((u64 *) seed); else return random_u32 (seed); } /** \brief Generate f64 random number in the interval [0,1] */ always_inline f64 random_f64 (u32 * seed) { return (f64) random_u32 (seed) / (f64) random_u32_max (); } /** \brief Generate random character vector From the alphabet a-z, lower case. Returns a vector of the supplied length which is NOT guaranteed to be NULL-terminated. FIXME? */ always_inline u8 * random_string (u32 * seed, uword len) { u8 *alphabet = (u8 *) "abcdefghijklmnopqrstuvwxyz"; u8 *s = 0; word i; vec_resize (s, len); for (i = 0; i < len; i++) s[i] = alphabet[random_u32 (seed) % 26]; return s; } #endif /* included_random_h */ /* * fd.io coding-style-patch-verification: ON * * Local Variables: * eval: (c-set-style "gnu") * End: */


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