author | Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com> |
Mon, 04 Oct 2010 02:56:42 +0300 | |
changeset 68 | ff3fc7722556 |
parent 0 | e4d67989cc36 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1983, 1993 |
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* The Regents of the University of California. All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 4. Neither the name of the University nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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* © Portions copyright (c) 2006 Nokia Corporation. All rights reserved. |
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*/ |
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|
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#if defined(LIBC_SCCS) && !defined(lint) |
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static char sccsid[] = "@(#)random.c 8.2 (Berkeley) 5/19/95"; |
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#endif /* LIBC_SCCS and not lint */ |
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#include <sys/cdefs.h> |
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__FBSDID("$FreeBSD: src/lib/libc/stdlib/random.c,v 1.24 2004/01/20 03:02:18 das Exp $"); |
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|
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#include <sys/time.h> /* for srandomdev() */ |
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#include <fcntl.h> /* for srandomdev() */ |
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#include <stdint.h> |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <unistd.h> /* for srandomdev() */ |
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|
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/* |
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* random.c: |
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* |
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* An improved random number generation package. In addition to the standard |
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* rand()/srand() like interface, this package also has a special state info |
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* interface. The initstate() routine is called with a seed, an array of |
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* bytes, and a count of how many bytes are being passed in; this array is |
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* then initialized to contain information for random number generation with |
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* that much state information. Good sizes for the amount of state |
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* information are 32, 64, 128, and 256 bytes. The state can be switched by |
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* calling the setstate() routine with the same array as was initiallized |
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* with initstate(). By default, the package runs with 128 bytes of state |
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* information and generates far better random numbers than a linear |
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* congruential generator. If the amount of state information is less than |
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* 32 bytes, a simple linear congruential R.N.G. is used. |
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* |
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* Internally, the state information is treated as an array of uint32_t's; the |
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* zeroeth element of the array is the type of R.N.G. being used (small |
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* integer); the remainder of the array is the state information for the |
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* R.N.G. Thus, 32 bytes of state information will give 7 ints worth of |
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* state information, which will allow a degree seven polynomial. (Note: |
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* the zeroeth word of state information also has some other information |
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* stored in it -- see setstate() for details). |
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* |
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* The random number generation technique is a linear feedback shift register |
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* approach, employing trinomials (since there are fewer terms to sum up that |
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* way). In this approach, the least significant bit of all the numbers in |
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* the state table will act as a linear feedback shift register, and will |
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* have period 2^deg - 1 (where deg is the degree of the polynomial being |
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* used, assuming that the polynomial is irreducible and primitive). The |
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* higher order bits will have longer periods, since their values are also |
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* influenced by pseudo-random carries out of the lower bits. The total |
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* period of the generator is approximately deg*(2**deg - 1); thus doubling |
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* the amount of state information has a vast influence on the period of the |
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* generator. Note: the deg*(2**deg - 1) is an approximation only good for |
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* large deg, when the period of the shift is the dominant factor. |
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* With deg equal to seven, the period is actually much longer than the |
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* 7*(2**7 - 1) predicted by this formula. |
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* |
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* Modified 28 December 1994 by Jacob S. Rosenberg. |
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* The following changes have been made: |
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* All references to the type u_int have been changed to unsigned long. |
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* All references to type int have been changed to type long. Other |
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* cleanups have been made as well. A warning for both initstate and |
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* setstate has been inserted to the effect that on Sparc platforms |
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* the 'arg_state' variable must be forced to begin on word boundaries. |
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* This can be easily done by casting a long integer array to char *. |
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* The overall logic has been left STRICTLY alone. This software was |
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* tested on both a VAX and Sun SpacsStation with exactly the same |
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* results. The new version and the original give IDENTICAL results. |
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* The new version is somewhat faster than the original. As the |
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* documentation says: "By default, the package runs with 128 bytes of |
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* state information and generates far better random numbers than a linear |
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* congruential generator. If the amount of state information is less than |
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* 32 bytes, a simple linear congruential R.N.G. is used." For a buffer of |
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* 128 bytes, this new version runs about 19 percent faster and for a 16 |
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* byte buffer it is about 5 percent faster. |
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*/ |
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102 |
|
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/* |
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* For each of the currently supported random number generators, we have a |
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* break value on the amount of state information (you need at least this |
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* many bytes of state info to support this random number generator), a degree |
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* for the polynomial (actually a trinomial) that the R.N.G. is based on, and |
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* the separation between the two lower order coefficients of the trinomial. |
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*/ |
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#define TYPE_0 0 /* linear congruential */ |
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#define BREAK_0 8 |
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#define DEG_0 0 |
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#define SEP_0 0 |
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114 |
|
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#define TYPE_1 1 /* x**7 + x**3 + 1 */ |
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#define BREAK_1 32 |
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#define DEG_1 7 |
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#define SEP_1 3 |
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119 |
|
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#define TYPE_2 2 /* x**15 + x + 1 */ |
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#define BREAK_2 64 |
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#define DEG_2 15 |
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#define SEP_2 1 |
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124 |
|
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#define TYPE_3 3 /* x**31 + x**3 + 1 */ |
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#define BREAK_3 128 |
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#define DEG_3 31 |
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#define SEP_3 3 |
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129 |
|
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#define TYPE_4 4 /* x**63 + x + 1 */ |
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#define BREAK_4 256 |
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#define DEG_4 63 |
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#define SEP_4 1 |
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134 |
|
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/* |
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* Array versions of the above information to make code run faster -- |
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* relies on fact that TYPE_i == i. |
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*/ |
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#define MAX_TYPES 5 /* max number of types above */ |
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140 |
|
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#ifdef USE_WEAK_SEEDING |
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#define NSHUFF 0 |
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#else /* !USE_WEAK_SEEDING */ |
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#define NSHUFF 50 /* to drop some "seed -> 1st value" linearity */ |
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#endif /* !USE_WEAK_SEEDING */ |
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146 |
|
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static const int degrees[MAX_TYPES] = { DEG_0, DEG_1, DEG_2, DEG_3, DEG_4 }; |
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static const int seps [MAX_TYPES] = { SEP_0, SEP_1, SEP_2, SEP_3, SEP_4 }; |
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149 |
|
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/* |
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* Initially, everything is set up as if from: |
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* |
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* initstate(1, randtbl, 128); |
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* |
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* Note that this initialization takes advantage of the fact that srandom() |
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* advances the front and rear pointers 10*rand_deg times, and hence the |
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* rear pointer which starts at 0 will also end up at zero; thus the zeroeth |
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* element of the state information, which contains info about the current |
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* position of the rear pointer is just |
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* |
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* MAX_TYPES * (rptr - state) + TYPE_3 == TYPE_3. |
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*/ |
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163 |
|
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static uint32_t randtbl[DEG_3 + 1] = { |
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TYPE_3, |
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#ifdef USE_WEAK_SEEDING |
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/* Historic implementation compatibility */ |
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/* The random sequences do not vary much with the seed */ |
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0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342, 0xde3b81e0, 0xdf0a6fb5, |
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0xf103bc02, 0x48f340fb, 0x7449e56b, 0xbeb1dbb0, 0xab5c5918, 0x946554fd, |
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0x8c2e680f, 0xeb3d799f, 0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, |
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0xe369735d, 0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc, |
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0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e, 0x8999220b, |
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0x27fb47b9, |
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#else /* !USE_WEAK_SEEDING */ |
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0x991539b1, 0x16a5bce3, 0x6774a4cd, 0x3e01511e, 0x4e508aaa, 0x61048c05, |
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0xf5500617, 0x846b7115, 0x6a19892c, 0x896a97af, 0xdb48f936, 0x14898454, |
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0x37ffd106, 0xb58bff9c, 0x59e17104, 0xcf918a49, 0x09378c83, 0x52c7a471, |
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0x8d293ea9, 0x1f4fc301, 0xc3db71be, 0x39b44e1c, 0xf8a44ef9, 0x4c8b80b1, |
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0x19edc328, 0x87bf4bdd, 0xc9b240e5, 0xe9ee4b1b, 0x4382aee7, 0x535b6b41, |
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0xf3bec5da |
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#endif /* !USE_WEAK_SEEDING */ |
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}; |
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184 |
|
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/* |
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* fptr and rptr are two pointers into the state info, a front and a rear |
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* pointer. These two pointers are always rand_sep places aparts, as they |
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* cycle cyclically through the state information. (Yes, this does mean we |
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* could get away with just one pointer, but the code for random() is more |
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* efficient this way). The pointers are left positioned as they would be |
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* from the call |
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* |
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* initstate(1, randtbl, 128); |
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* |
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* (The position of the rear pointer, rptr, is really 0 (as explained above |
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* in the initialization of randtbl) because the state table pointer is set |
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* to point to randtbl[1] (as explained below). |
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*/ |
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static uint32_t *fptr = &randtbl[SEP_3 + 1]; |
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static uint32_t *rptr = &randtbl[1]; |
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201 |
|
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/* |
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* The following things are the pointer to the state information table, the |
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* type of the current generator, the degree of the current polynomial being |
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* used, and the separation between the two pointers. Note that for efficiency |
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* of random(), we remember the first location of the state information, not |
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* the zeroeth. Hence it is valid to access state[-1], which is used to |
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* store the type of the R.N.G. Also, we remember the last location, since |
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* this is more efficient than indexing every time to find the address of |
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* the last element to see if the front and rear pointers have wrapped. |
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*/ |
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static uint32_t *state = &randtbl[1]; |
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static int rand_type = TYPE_3; |
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static int rand_deg = DEG_3; |
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static int rand_sep = SEP_3; |
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static uint32_t *end_ptr = &randtbl[DEG_3 + 1]; |
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217 |
|
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static inline uint32_t good_rand(int32_t); |
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219 |
|
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static inline uint32_t good_rand (x) |
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int32_t x; |
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{ |
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#ifdef USE_WEAK_SEEDING |
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/* |
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* Historic implementation compatibility. |
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* The random sequences do not vary much with the seed, |
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* even with overflowing. |
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*/ |
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return (1103515245 * x + 12345); |
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#else /* !USE_WEAK_SEEDING */ |
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/* |
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* Compute x = (7^5 * x) mod (2^31 - 1) |
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* wihout overflowing 31 bits: |
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* (2^31 - 1) = 127773 * (7^5) + 2836 |
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* From "Random number generators: good ones are hard to find", |
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* Park and Miller, Communications of the ACM, vol. 31, no. 10, |
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* October 1988, p. 1195. |
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*/ |
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int32_t hi, lo; |
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240 |
|
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/* Can't be initialized with 0, so use another value. */ |
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if (x == 0) |
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x = 123459876; |
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hi = x / 127773; |
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lo = x % 127773; |
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x = 16807 * lo - 2836 * hi; |
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if (x < 0) |
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x += 0x7fffffff; |
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return (x); |
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#endif /* !USE_WEAK_SEEDING */ |
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} |
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252 |
|
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/* |
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* srandom: |
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* |
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* Initialize the random number generator based on the given seed. If the |
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* type is the trivial no-state-information type, just remember the seed. |
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* Otherwise, initializes state[] based on the given "seed" via a linear |
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* congruential generator. Then, the pointers are set to known locations |
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* that are exactly rand_sep places apart. Lastly, it cycles the state |
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* information a given number of times to get rid of any initial dependencies |
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* introduced by the L.C.R.N.G. Note that the initialization of randtbl[] |
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* for default usage relies on values produced by this routine. |
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*/ |
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265 |
|
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EXPORT_C |
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void |
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srandom(x) |
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unsigned long x; |
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{ |
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int i, lim; |
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|
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state[0] = (uint32_t)x; |
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if (rand_type == TYPE_0) |
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lim = NSHUFF; |
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else { |
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for (i = 1; i < rand_deg; i++) |
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state[i] = good_rand(state[i - 1]); |
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fptr = &state[rand_sep]; |
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rptr = &state[0]; |
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lim = 10 * rand_deg; |
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} |
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for (i = 0; i < lim; i++) |
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(void)random(); |
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} |
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#ifdef __SYMBIAN_COMPILE_UNUSED__ |
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/* |
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* srandomdev: |
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* |
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* Many programs choose the seed value in a totally predictable manner. |
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* This often causes problems. We seed the generator using the much more |
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* secure random(4) interface. Note that this particular seeding |
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* procedure can generate states which are impossible to reproduce by |
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* calling srandom() with any value, since the succeeding terms in the |
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* state buffer are no longer derived from the LC algorithm applied to |
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* a fixed seed. |
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*/ |
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void |
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srandomdev() |
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|
300 |
{ |
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|
301 |
int fd, done; |
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|
302 |
size_t len; |
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|
303 |
|
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|
304 |
if (rand_type == TYPE_0) |
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|
305 |
len = sizeof state[0]; |
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|
306 |
else |
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|
307 |
len = rand_deg * sizeof state[0]; |
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diff
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|
308 |
|
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|
309 |
done = 0; |
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|
310 |
fd = open("/dev/random", O_RDONLY, 0); |
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|
311 |
if (fd >= 0) { |
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|
312 |
if (read(fd, (void *) state, len) == (ssize_t) len) |
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|
313 |
done = 1; |
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|
314 |
close(fd); |
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|
315 |
} |
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|
316 |
|
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|
317 |
if (!done) { |
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|
318 |
struct timeval tv; |
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|
319 |
unsigned long junk = 0; |
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|
320 |
|
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|
321 |
gettimeofday(&tv, NULL); |
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|
322 |
srandom((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec ^ junk); |
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323 |
return; |
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|
324 |
} |
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|
325 |
|
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|
326 |
if (rand_type != TYPE_0) { |
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|
327 |
fptr = &state[rand_sep]; |
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|
328 |
rptr = &state[0]; |
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|
329 |
} |
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|
330 |
} |
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|
331 |
#endif |
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|
332 |
/* |
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diff
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|
333 |
* initstate: |
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|
334 |
* |
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|
335 |
* Initialize the state information in the given array of n bytes for future |
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Revision: 201002
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parents:
diff
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|
336 |
* random number generation. Based on the number of bytes we are given, and |
e4d67989cc36
Revision: 201002
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diff
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|
337 |
* the break values for the different R.N.G.'s, we choose the best (largest) |
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parents:
diff
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|
338 |
* one we can and set things up for it. srandom() is then called to |
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|
339 |
* initialize the state information. |
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|
340 |
* |
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|
341 |
* Note that on return from srandom(), we set state[-1] to be the type |
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Revision: 201002
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|
342 |
* multiplexed with the current value of the rear pointer; this is so |
e4d67989cc36
Revision: 201002
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diff
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|
343 |
* successive calls to initstate() won't lose this information and will be |
e4d67989cc36
Revision: 201002
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parents:
diff
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|
344 |
* able to restart with setstate(). |
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|
345 |
* |
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|
346 |
* Note: the first thing we do is save the current state, if any, just like |
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Revision: 201002
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|
347 |
* setstate() so that it doesn't matter when initstate is called. |
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|
348 |
* |
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|
349 |
* Returns a pointer to the old state. |
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|
350 |
* |
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|
351 |
* Note: The Sparc platform requires that arg_state begin on an int |
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|
352 |
* word boundary; otherwise a bus error will occur. Even so, lint will |
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Revision: 201002
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|
353 |
* complain about mis-alignment, but you should disregard these messages. |
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|
354 |
*/ |
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|
355 |
|
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|
356 |
EXPORT_C |
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|
357 |
char * |
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|
358 |
initstate(seed, arg_state, n) |
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|
359 |
unsigned long seed; /* seed for R.N.G. */ |
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|
360 |
char *arg_state; /* pointer to state array */ |
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|
361 |
long n; /* # bytes of state info */ |
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Revision: 201002
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diff
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|
362 |
{ |
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Revision: 201002
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parents:
diff
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|
363 |
char *ostate = (char *)(&state[-1]); |
e4d67989cc36
Revision: 201002
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parents:
diff
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|
364 |
uint32_t *int_arg_state = (uint32_t *)arg_state; |
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parents:
diff
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|
365 |
|
e4d67989cc36
Revision: 201002
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parents:
diff
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|
366 |
if (rand_type == TYPE_0) |
e4d67989cc36
Revision: 201002
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parents:
diff
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|
367 |
state[-1] = rand_type; |
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Revision: 201002
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parents:
diff
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|
368 |
else |
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diff
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|
369 |
state[-1] = MAX_TYPES * (rptr - state) + rand_type; |
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Revision: 201002
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parents:
diff
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|
370 |
if (n < BREAK_0) { |
e4d67989cc36
Revision: 201002
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parents:
diff
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|
371 |
(void)fprintf(stderr, |
e4d67989cc36
Revision: 201002
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parents:
diff
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|
372 |
"random: not enough state (%ld bytes); ignored.\n", n); |
e4d67989cc36
Revision: 201002
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parents:
diff
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|
373 |
return(0); |
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Revision: 201002
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parents:
diff
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|
374 |
} |
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Revision: 201002
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parents:
diff
changeset
|
375 |
if (n < BREAK_1) { |
e4d67989cc36
Revision: 201002
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parents:
diff
changeset
|
376 |
rand_type = TYPE_0; |
e4d67989cc36
Revision: 201002
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parents:
diff
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|
377 |
rand_deg = DEG_0; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
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|
378 |
rand_sep = SEP_0; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
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|
379 |
} else if (n < BREAK_2) { |
e4d67989cc36
Revision: 201002
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parents:
diff
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|
380 |
rand_type = TYPE_1; |
e4d67989cc36
Revision: 201002
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parents:
diff
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|
381 |
rand_deg = DEG_1; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
382 |
rand_sep = SEP_1; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
383 |
} else if (n < BREAK_3) { |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
384 |
rand_type = TYPE_2; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
385 |
rand_deg = DEG_2; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
386 |
rand_sep = SEP_2; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
387 |
} else if (n < BREAK_4) { |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
388 |
rand_type = TYPE_3; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
389 |
rand_deg = DEG_3; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
390 |
rand_sep = SEP_3; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
391 |
} else { |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
392 |
rand_type = TYPE_4; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
393 |
rand_deg = DEG_4; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
394 |
rand_sep = SEP_4; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
395 |
} |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
396 |
state = int_arg_state + 1; /* first location */ |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
397 |
end_ptr = &state[rand_deg]; /* must set end_ptr before srandom */ |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
398 |
srandom(seed); |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
399 |
if (rand_type == TYPE_0) |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
400 |
int_arg_state[0] = rand_type; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
401 |
else |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
402 |
int_arg_state[0] = MAX_TYPES * (rptr - state) + rand_type; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
403 |
return(ostate); |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
404 |
} |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
405 |
|
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
406 |
/* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
407 |
* setstate: |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
408 |
* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
409 |
* Restore the state from the given state array. |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
410 |
* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
411 |
* Note: it is important that we also remember the locations of the pointers |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
412 |
* in the current state information, and restore the locations of the pointers |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
413 |
* from the old state information. This is done by multiplexing the pointer |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
414 |
* location into the zeroeth word of the state information. |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
415 |
* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
416 |
* Note that due to the order in which things are done, it is OK to call |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
417 |
* setstate() with the same state as the current state. |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
418 |
* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
419 |
* Returns a pointer to the old state information. |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
420 |
* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
421 |
* Note: The Sparc platform requires that arg_state begin on an int |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
422 |
* word boundary; otherwise a bus error will occur. Even so, lint will |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
423 |
* complain about mis-alignment, but you should disregard these messages. |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
424 |
*/ |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
425 |
|
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
426 |
EXPORT_C |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
427 |
char * |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
428 |
setstate(arg_state) |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
429 |
char *arg_state; /* pointer to state array */ |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
430 |
{ |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
431 |
uint32_t *new_state = (uint32_t *)arg_state; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
432 |
uint32_t type = new_state[0] % MAX_TYPES; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
433 |
uint32_t rear = new_state[0] / MAX_TYPES; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
434 |
char *ostate = (char *)(&state[-1]); |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
435 |
|
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
436 |
if (rand_type == TYPE_0) |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
437 |
state[-1] = rand_type; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
438 |
else |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
439 |
state[-1] = MAX_TYPES * (rptr - state) + rand_type; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
440 |
switch(type) { |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
441 |
case TYPE_0: |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
442 |
case TYPE_1: |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
443 |
case TYPE_2: |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
444 |
case TYPE_3: |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
445 |
case TYPE_4: |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
446 |
rand_type = type; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
447 |
rand_deg = degrees[type]; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
448 |
rand_sep = seps[type]; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
449 |
break; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
450 |
default: |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
451 |
(void)fprintf(stderr, |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
452 |
"random: state info corrupted; not changed.\n"); |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
453 |
} |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
454 |
state = new_state + 1; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
455 |
if (rand_type != TYPE_0) { |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
456 |
rptr = &state[rear]; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
457 |
fptr = &state[(rear + rand_sep) % rand_deg]; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
458 |
} |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
459 |
end_ptr = &state[rand_deg]; /* set end_ptr too */ |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
460 |
return(ostate); |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
461 |
} |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
462 |
|
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
463 |
/* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
464 |
* random: |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
465 |
* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
466 |
* If we are using the trivial TYPE_0 R.N.G., just do the old linear |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
467 |
* congruential bit. Otherwise, we do our fancy trinomial stuff, which is |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
468 |
* the same in all the other cases due to all the global variables that have |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
469 |
* been set up. The basic operation is to add the number at the rear pointer |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
470 |
* into the one at the front pointer. Then both pointers are advanced to |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
471 |
* the next location cyclically in the table. The value returned is the sum |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
472 |
* generated, reduced to 31 bits by throwing away the "least random" low bit. |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
473 |
* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
474 |
* Note: the code takes advantage of the fact that both the front and |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
475 |
* rear pointers can't wrap on the same call by not testing the rear |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
476 |
* pointer if the front one has wrapped. |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
477 |
* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
478 |
* Returns a 31-bit random number. |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
479 |
*/ |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
480 |
|
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
481 |
EXPORT_C |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
482 |
long |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
483 |
random() |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
484 |
{ |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
485 |
uint32_t i; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
486 |
uint32_t *f, *r; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
487 |
|
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
488 |
if (rand_type == TYPE_0) { |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
489 |
i = state[0]; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
490 |
state[0] = i = (good_rand(i)) & 0x7fffffff; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
491 |
} else { |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
492 |
/* |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
493 |
* Use local variables rather than static variables for speed. |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
494 |
*/ |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
495 |
f = fptr; r = rptr; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
496 |
*f += *r; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
497 |
i = (*f >> 1) & 0x7fffffff; /* chucking least random bit */ |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
498 |
if (++f >= end_ptr) { |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
499 |
f = state; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
500 |
++r; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
501 |
} |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
502 |
else if (++r >= end_ptr) { |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
503 |
r = state; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
504 |
} |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
505 |
|
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
506 |
fptr = f; rptr = r; |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
507 |
} |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
508 |
return((long)i); |
e4d67989cc36
Revision: 201002
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
509 |
} |