1 /* 2 * Copyright 2013 Haiku, Inc. All rights reserved. 3 * Distributed under the terms of the MIT License. 4 * 5 * Authors: 6 * Paweł Dziepak, pdziepak@quarnos.org 7 */ 8 #ifndef KERNEL_UTIL_RANDOM_H 9 #define KERNEL_UTIL_RANDOM_H 10 11 12 #include <smp.h> 13 #include <SupportDefs.h> 14 15 16 #define MAX_FAST_RANDOM_VALUE 0x7fff 17 #define MAX_RANDOM_VALUE 0x7fffffffu 18 #define MAX_SECURE_RANDOM_VALUE 0xffffffffu 19 20 static const int kFastRandomShift = 15; 21 static const int kRandomShift = 31; 22 static const int kSecureRandomShift = 32; 23 24 #ifdef __cplusplus 25 extern "C" { 26 #endif 27 28 unsigned int fast_random_value(void); 29 unsigned int random_value(void); 30 unsigned int secure_random_value(void); 31 32 #ifdef __cplusplus 33 } 34 #endif 35 36 37 #ifdef __cplusplus 38 39 template<typename T> 40 T 41 fast_get_random() 42 { 43 size_t shift = 0; 44 T random = 0; 45 while (shift < sizeof(T) * 8) { 46 random |= (T)fast_random_value() << shift; 47 shift += kFastRandomShift; 48 } 49 50 return random; 51 } 52 53 54 template<typename T> 55 T 56 get_random() 57 { 58 size_t shift = 0; 59 T random = 0; 60 while (shift < sizeof(T) * 8) { 61 random |= (T)random_value() << shift; 62 shift += kRandomShift; 63 } 64 65 return random; 66 } 67 68 69 template<typename T> 70 T 71 secure_get_random() 72 { 73 size_t shift = 0; 74 T random = 0; 75 while (shift < sizeof(T) * 8) { 76 random |= (T)secure_random_value() << shift; 77 shift += kSecureRandomShift; 78 } 79 80 return random; 81 } 82 83 84 #endif // __cplusplus 85 86 #endif // KERNEL_UTIL_RANDOM_H 87 88