From cb9cadad578297ffd78fa8a33670bdf1ab669e7e Mon Sep 17 00:00:00 2001 From: Ed Warnicke Date: Tue, 8 Dec 2015 15:45:58 -0700 Subject: Initial commit of vpp code. Change-Id: Ib246f1fbfce93274020ee93ce461e3d8bd8b9f17 Signed-off-by: Ed Warnicke --- vppinfra/vppinfra/random.h | 156 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 156 insertions(+) create mode 100644 vppinfra/vppinfra/random.h (limited to 'vppinfra/vppinfra/random.h') diff --git a/vppinfra/vppinfra/random.h b/vppinfra/vppinfra/random.h new file mode 100644 index 00000000000..1347c47c6f7 --- /dev/null +++ b/vppinfra/vppinfra/random.h @@ -0,0 +1,156 @@ +/* + * 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 +#include /* for vec_resize */ +#include /* 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 /* 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 /* 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 + + created via two calls to random_u32(). Quick and dirty. +*/ +always_inline u64 +random_u64 (u32 * seed) +{ + u64 result; + + result = (u64) random_u32 (seed) << 32; + result |= random_u32 (seed); + return result; +} + +/** \brief machine word size random number generator */ + +always_inline uword +random_uword (u32 * seed) +{ + if (sizeof (uword) == sizeof (u64)) + return random_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 */ -- cgit 1.2.3-korg