1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 /* Copyright (c) 1988 AT&T */ 28 /* All Rights Reserved */ 29 30 /* 31 * drand48, etc. pseudo-random number generator 32 * This implementation assumes unsigned short integers of at least 33 * 16 bits, long integers of at least 32 bits, and ignores 34 * overflows on adding or multiplying two unsigned integers. 35 * Two's-complement representation is assumed in a few places. 36 * Some extra masking is done if unsigneds are exactly 16 bits 37 * or longs are exactly 32 bits, but so what? 38 * An assembly-language implementation would run significantly faster. 39 */ 40 /* 41 * New assumptions (supercede those stated above) for 64-bit work. 42 * Longs are now 64 bits, and we are bound by standards to return 43 * type long, hovever all internal calculations where long was 44 * previously used (32 bit precision) are now using the int32_t 45 * type (32 bit precision in both ILP32 and LP64 worlds). 46 */ 47 48 #include <sys/mutex.h> 49 50 static kmutex_t seed_lock; 51 static int init48done = 0; 52 53 #define EXPORT0(TYPE, fn, fnu) TYPE fn() { \ 54 TYPE res; \ 55 mutex_enter(&seed_lock); \ 56 res = fnu(); \ 57 mutex_exit(&seed_lock); \ 58 return (res); } 59 #define EXPORT1(TYPE, fn, fnu) TYPE fn(unsigned short xsubi[3]) { \ 60 TYPE res; \ 61 mutex_enter(&seed_lock); \ 62 res = fnu(xsubi); \ 63 mutex_exit(&seed_lock); \ 64 return (res); } 65 66 #define N 16 67 #define MASK ((unsigned)(1 << (N - 1)) + (1 << (N - 1)) - 1) 68 #define LOW(x) ((unsigned)(x) & MASK) 69 #define HIGH(x) LOW((x) >> N) 70 #define MUL(x, y, z) { int32_t l = (int32_t)(x) * (int32_t)(y); \ 71 (z)[0] = LOW(l); (z)[1] = HIGH(l); } 72 #define CARRY(x, y) ((int32_t)(x) + (int32_t)(y) > MASK) 73 #define ADDEQU(x, y, z) (z = CARRY(x, (y)), x = LOW(x + (y))) 74 #define X0 0x330E 75 #define X1 0xABCD 76 #define X2 0x1234 77 #define A0 0xE66D 78 #define A1 0xDEEC 79 #define A2 0x5 80 #define C 0xB 81 #define SET3(x, x0, x1, x2) ((x)[0] = (x0), (x)[1] = (x1), (x)[2] = (x2)) 82 #define SETLOW(x, y, n) SET3(x, LOW((y)[n]), LOW((y)[(n)+1]), LOW((y)[(n)+2])) 83 #define SEED(x0, x1, x2) (SET3(x, x0, x1, x2), SET3(a, A0, A1, A2), c = C) 84 #define REST(v) for (i = 0; i < 3; i++) { xsubi[i] = x[i]; x[i] = temp[i]; } \ 85 return (v) 86 #define NEST(TYPE, f, F) static TYPE f(unsigned short *xsubi) { \ 87 int i; TYPE v; unsigned temp[3]; \ 88 for (i = 0; i < 3; i++) { temp[i] = x[i]; x[i] = LOW(xsubi[i]); } \ 89 v = F(); REST(v); } 90 91 /* Way ugly solution to problem names, but it works */ 92 #define x _drand48_x 93 #define a _drand48_a 94 #define c _drand48_c 95 /* End way ugly */ 96 static unsigned x[3] = { X0, X1, X2 }, a[3] = { A0, A1, A2 }, c = C; 97 static unsigned short lastx[3]; 98 static void next(void); 99 100 static long 101 ipf_r_lrand48_u(void) 102 { 103 next(); 104 return ((long)((int32_t)x[2] << (N - 1)) + (x[1] >> 1)); 105 } 106 107 static void 108 init48(void) 109 { 110 mutex_init(&seed_lock, 0L, MUTEX_DRIVER, 0L); 111 init48done = 1; 112 } 113 114 static long 115 ipf_r_mrand48_u(void) 116 { 117 next(); 118 return ((long)((int32_t)x[2] << N) + x[1]); 119 } 120 121 static void 122 next(void) 123 { 124 unsigned p[2], q[2], r[2], carry0, carry1; 125 126 MUL(a[0], x[0], p); 127 ADDEQU(p[0], c, carry0); 128 ADDEQU(p[1], carry0, carry1); 129 MUL(a[0], x[1], q); 130 ADDEQU(p[1], q[0], carry0); 131 MUL(a[1], x[0], r); 132 x[2] = LOW(carry0 + carry1 + CARRY(p[1], r[0]) + q[1] + r[1] + 133 a[0] * x[2] + a[1] * x[1] + a[2] * x[0]); 134 x[1] = LOW(p[1] + r[0]); 135 x[0] = LOW(p[0]); 136 } 137 138 void 139 ipf_r_srand48(long seedval) 140 { 141 int32_t fixseed = (int32_t)seedval; /* limit to 32 bits */ 142 143 if (init48done == 0) 144 init48(); 145 mutex_enter(&seed_lock); 146 SEED(X0, LOW(fixseed), HIGH(fixseed)); 147 mutex_exit(&seed_lock); 148 } 149 150 EXPORT0(long, ipf_r_lrand48, ipf_r_lrand48_u) 151 152 #include <sys/random.h> 153 154 unsigned 155 ipf_random() 156 { 157 static int seeded = 0; 158 159 if (seeded == 0) { 160 long seed; 161 162 /* 163 * Keep reseeding until some good randomness comes from the 164 * kernel. One of two things will happen: it will succeed or 165 * it will fail (with poor randomness), thus creating NAT 166 * sessions will be "slow" until enough randomness is gained 167 * to not need to get more. It isn't necessary to initialise 168 * seed as it will just pickup whatever random garbage has 169 * been left on the heap and that's good enough until we 170 * get some good garbage. 171 */ 172 if (random_get_bytes((uint8_t *)&seed, sizeof (seed)) == 0) 173 seeded = 1; 174 ipf_r_srand48(seed); 175 } 176 177 return (unsigned)ipf_r_lrand48(); 178 } 179