Greg Steiert / pegasus_dev

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Dependents:   blinky_max32630fthr

features/FEATURE_COMMON_PAL/mbed-client-randlib/linux/randLIB.c@3:1198227e6421, 2016-12-16 (annotated)

Committer:
switches
Date:
Fri Dec 16 16:27:57 2016 +0000
Revision:
3:1198227e6421
Parent:
0:5c4d7b2438d3 
Changed ADC scale for MAX32625 platforms to 1.2V full scale to match MAX32630 platforms

Who changed what in which revision?

UserRevisionLine numberNew contents of line
switches 0:5c4d7b2438d3 1 /*
switches 0:5c4d7b2438d3 2 * Copyright (c) 2014-2015 ARM Limited. All rights reserved.
switches 0:5c4d7b2438d3 3 * SPDX-License-Identifier: Apache-2.0
switches 0:5c4d7b2438d3 4 * Licensed under the Apache License, Version 2.0 (the License); you may
switches 0:5c4d7b2438d3 5 * not use this file except in compliance with the License.
switches 0:5c4d7b2438d3 6 * You may obtain a copy of the License at
switches 0:5c4d7b2438d3 7 *
switches 0:5c4d7b2438d3 8 * http://www.apache.org/licenses/LICENSE-2.0
switches 0:5c4d7b2438d3 9 *
switches 0:5c4d7b2438d3 10 * Unless required by applicable law or agreed to in writing, software
switches 0:5c4d7b2438d3 11 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
switches 0:5c4d7b2438d3 12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
switches 0:5c4d7b2438d3 13 * See the License for the specific language governing permissions and
switches 0:5c4d7b2438d3 14 * limitations under the License.
switches 0:5c4d7b2438d3 15 */
switches 0:5c4d7b2438d3 16 #include <stdint.h>
switches 0:5c4d7b2438d3 17 #include <stdlib.h>
switches 0:5c4d7b2438d3 18 #include <sys/types.h>
switches 0:5c4d7b2438d3 19 #include <sys/stat.h>
switches 0:5c4d7b2438d3 20 #include <fcntl.h>
switches 0:5c4d7b2438d3 21 #include <unistd.h>
switches 0:5c4d7b2438d3 22 #include "randLIB.h"
switches 0:5c4d7b2438d3 23
switches 0:5c4d7b2438d3 24 /**
switches 0:5c4d7b2438d3 25 * \brief Init seed for Pseudo Random.
switches 0:5c4d7b2438d3 26 * On a Linux, this does nothing.
switches 0:5c4d7b2438d3 27 *
switches 0:5c4d7b2438d3 28 * \return None
switches 0:5c4d7b2438d3 29 *
switches 0:5c4d7b2438d3 30 */
switches 0:5c4d7b2438d3 31 void randLIB_seed_random(void)
switches 0:5c4d7b2438d3 32 {
switches 0:5c4d7b2438d3 33 }
switches 0:5c4d7b2438d3 34
switches 0:5c4d7b2438d3 35 /**
switches 0:5c4d7b2438d3 36 * \brief Generate 8-bit random number.
switches 0:5c4d7b2438d3 37 *
switches 0:5c4d7b2438d3 38 * \param None
switches 0:5c4d7b2438d3 39 * \return 8-bit random number
switches 0:5c4d7b2438d3 40 *
switches 0:5c4d7b2438d3 41 */
switches 0:5c4d7b2438d3 42 uint8_t randLIB_get_8bit(void)
switches 0:5c4d7b2438d3 43 {
switches 0:5c4d7b2438d3 44 uint8_t ret_val;
switches 0:5c4d7b2438d3 45 randLIB_get_n_bytes_random(&ret_val, 1);
switches 0:5c4d7b2438d3 46 return ret_val;
switches 0:5c4d7b2438d3 47 }
switches 0:5c4d7b2438d3 48
switches 0:5c4d7b2438d3 49 /**
switches 0:5c4d7b2438d3 50 * \brief Generate 16-bit random number.
switches 0:5c4d7b2438d3 51 *
switches 0:5c4d7b2438d3 52 * \param None
switches 0:5c4d7b2438d3 53 * \return 16-bit random number
switches 0:5c4d7b2438d3 54 *
switches 0:5c4d7b2438d3 55 */
switches 0:5c4d7b2438d3 56 uint16_t randLIB_get_16bit(void)
switches 0:5c4d7b2438d3 57 {
switches 0:5c4d7b2438d3 58 uint16_t ret_val;
switches 0:5c4d7b2438d3 59
switches 0:5c4d7b2438d3 60 randLIB_get_n_bytes_random((uint8_t*)&ret_val, 2);
switches 0:5c4d7b2438d3 61 return ret_val;
switches 0:5c4d7b2438d3 62 }
switches 0:5c4d7b2438d3 63 /**
switches 0:5c4d7b2438d3 64 * \brief Generate 32-bit random number.
switches 0:5c4d7b2438d3 65 *
switches 0:5c4d7b2438d3 66 * \param None
switches 0:5c4d7b2438d3 67 * \return 32-bit random number
switches 0:5c4d7b2438d3 68 *
switches 0:5c4d7b2438d3 69 */
switches 0:5c4d7b2438d3 70 uint32_t randLIB_get_32bit(void)
switches 0:5c4d7b2438d3 71 {
switches 0:5c4d7b2438d3 72 uint32_t ret_val;
switches 0:5c4d7b2438d3 73 randLIB_get_n_bytes_random((uint8_t*)&ret_val, 4);
switches 0:5c4d7b2438d3 74 return ret_val;
switches 0:5c4d7b2438d3 75 }
switches 0:5c4d7b2438d3 76
switches 0:5c4d7b2438d3 77
switches 0:5c4d7b2438d3 78 /**
switches 0:5c4d7b2438d3 79 * \brief Generate n-bytes random numbers.
switches 0:5c4d7b2438d3 80 *
switches 0:5c4d7b2438d3 81 * \param data_ptr pointer where random will be stored
switches 0:5c4d7b2438d3 82 * \param eight_bit_boundary how many bytes need random
switches 0:5c4d7b2438d3 83 * \return 0 process valid
switches 0:5c4d7b2438d3 84 * \return -1 Unsupported Parameters or failed to get random data.
switches 0:5c4d7b2438d3 85 *
switches 0:5c4d7b2438d3 86 */
switches 0:5c4d7b2438d3 87 int8_t randLIB_get_n_bytes_random(uint8_t *data_ptr, uint8_t eight_bit_boundary)
switches 0:5c4d7b2438d3 88 {
switches 0:5c4d7b2438d3 89 if ((data_ptr == 0) || (eight_bit_boundary == 0)) {
switches 0:5c4d7b2438d3 90 return -1;
switches 0:5c4d7b2438d3 91 }
switches 0:5c4d7b2438d3 92
switches 0:5c4d7b2438d3 93 int fd = open("/dev/urandom", O_RDONLY);
switches 0:5c4d7b2438d3 94 if (fd != -1) {
switches 0:5c4d7b2438d3 95 size_t len = read(fd, data_ptr, eight_bit_boundary);
switches 0:5c4d7b2438d3 96 close(fd);
switches 0:5c4d7b2438d3 97 if (len == eight_bit_boundary)
switches 0:5c4d7b2438d3 98 return 0;
switches 0:5c4d7b2438d3 99 }
switches 0:5c4d7b2438d3 100
switches 0:5c4d7b2438d3 101 return -1;
switches 0:5c4d7b2438d3 102 }
switches 0:5c4d7b2438d3 103
switches 0:5c4d7b2438d3 104 /**
switches 0:5c4d7b2438d3 105 * \brief Generate a random number within a range.
switches 0:5c4d7b2438d3 106 *
switches 0:5c4d7b2438d3 107 * The result is linearly distributed in the range [min..max], inclusive.
switches 0:5c4d7b2438d3 108 *
switches 0:5c4d7b2438d3 109 * \param min minimum value that can be generated
switches 0:5c4d7b2438d3 110 * \param max maximum value that can be generated
switches 0:5c4d7b2438d3 111 */
switches 0:5c4d7b2438d3 112 uint16_t randLIB_get_random_in_range(uint16_t min, uint16_t max)
switches 0:5c4d7b2438d3 113 {
switches 0:5c4d7b2438d3 114 /* This special case is potentially common, particularly in this routine's
switches 0:5c4d7b2438d3 115 * first user (Trickle), so worth catching immediately */
switches 0:5c4d7b2438d3 116 if (min == max) {
switches 0:5c4d7b2438d3 117 return min;
switches 0:5c4d7b2438d3 118 }
switches 0:5c4d7b2438d3 119
switches 0:5c4d7b2438d3 120 /* 16-bit arithmetic below fails in this extreme case; we can optimise it */
switches 0:5c4d7b2438d3 121 if (max - min == 0xFFFF) {
switches 0:5c4d7b2438d3 122 return randLIB_get_16bit();
switches 0:5c4d7b2438d3 123 }
switches 0:5c4d7b2438d3 124
switches 0:5c4d7b2438d3 125 unsigned int values_needed = max + 1 - min;
switches 0:5c4d7b2438d3 126 unsigned int band_size = 0x10000u / values_needed;
switches 0:5c4d7b2438d3 127 unsigned int top_of_bands = band_size * values_needed;
switches 0:5c4d7b2438d3 128 unsigned int result;
switches 0:5c4d7b2438d3 129 do {
switches 0:5c4d7b2438d3 130 result = randLIB_get_16bit();
switches 0:5c4d7b2438d3 131 } while (result >= top_of_bands);
switches 0:5c4d7b2438d3 132
switches 0:5c4d7b2438d3 133 return min + (uint16_t)(result / band_size);
switches 0:5c4d7b2438d3 134 }
switches 0:5c4d7b2438d3 135
switches 0:5c4d7b2438d3 136 /**
switches 0:5c4d7b2438d3 137 * \brief Randomise a base 32-bit number by a jitter factor
switches 0:5c4d7b2438d3 138 *
switches 0:5c4d7b2438d3 139 * The result is linearly distributed in the jitter range, which is expressed
switches 0:5c4d7b2438d3 140 * as fixed-point unsigned 1.15 values. For example, to produce a number in the
switches 0:5c4d7b2438d3 141 * range [0.75 * base, 1.25 * base], set min_factor to 0x6000 and max_factor to
switches 0:5c4d7b2438d3 142 * 0xA000.
switches 0:5c4d7b2438d3 143 *
switches 0:5c4d7b2438d3 144 * Result is clamped to 0xFFFFFFFF if it overflows.
switches 0:5c4d7b2438d3 145 *
switches 0:5c4d7b2438d3 146 * \param base The base 32-bit value
switches 0:5c4d7b2438d3 147 * \param min_factor The minimum value for the random factor
switches 0:5c4d7b2438d3 148 * \param max_factor The maximum value for the random factor
switches 0:5c4d7b2438d3 149 */
switches 0:5c4d7b2438d3 150 uint32_t randLIB_randomise_base(uint32_t base, uint16_t min_factor, uint16_t max_factor)
switches 0:5c4d7b2438d3 151 {
switches 0:5c4d7b2438d3 152 uint16_t random_factor = randLIB_get_random_in_range(min_factor, max_factor);
switches 0:5c4d7b2438d3 153
switches 0:5c4d7b2438d3 154 /* 32x16-bit long multiplication, to get 48-bit result */
switches 0:5c4d7b2438d3 155 uint32_t hi = (base >> 16) * random_factor;
switches 0:5c4d7b2438d3 156 uint32_t lo = (base & 0xFFFF) * random_factor;
switches 0:5c4d7b2438d3 157 /* Add halves, and take top 32 bits of 48-bit result */
switches 0:5c4d7b2438d3 158 uint32_t res = hi + (lo >> 16);
switches 0:5c4d7b2438d3 159
switches 0:5c4d7b2438d3 160 /* Randomisation factor is *2^15, so need to shift up 1 more bit, avoiding overflow */
switches 0:5c4d7b2438d3 161 if (res & 0x80000000) {
switches 0:5c4d7b2438d3 162 res = 0xFFFFFFFF;
switches 0:5c4d7b2438d3 163 } else {
switches 0:5c4d7b2438d3 164 res = (res << 1) | ((lo >> 15) & 1);
switches 0:5c4d7b2438d3 165 }
switches 0:5c4d7b2438d3 166
switches 0:5c4d7b2438d3 167 return res;
switches 0:5c4d7b2438d3 168 }