70 lines
1.5 KiB
C
70 lines
1.5 KiB
C
/*
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* Copyright (c) 2013-2014 Wind River Systems, Inc.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* @file
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* @brief Non-random number generator based on x86 CPU timestamp
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*
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* This module provides a non-random implementation of sys_rand32_get(), which
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* is not meant to be used in a final product as a truly random number
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* generator. It was provided to allow testing on a platform that does not (yet)
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* provide a random number generator.
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*/
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#include <kernel.h>
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#include <arch/cpu.h>
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#include <random/rand32.h>
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#include <string.h>
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/**
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*
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* @brief Get a 32 bit random number
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*
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* The non-random number generator returns values that are based off the
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* CPU's timestamp counter, which means that successive calls will normally
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* display ever-increasing values.
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*
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* @return a 32-bit number
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*/
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u32_t sys_rand32_get(void)
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{
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return z_do_read_cpu_timestamp32();
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}
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/**
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*
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* @brief Fill destination buffer with random numbers
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*
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* The non-random number generator returns values that are based off the
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* target's clock counter, which means that successive calls will return
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* different values.
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*
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* @param dst destination buffer to fill
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* @param outlen size of destination buffer to fill
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*
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* @return N/A
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*/
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void sys_rand_get(void *dst, size_t outlen)
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{
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u32_t len = 0;
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u32_t blocksize = 4;
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u32_t ret;
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u32_t *udst = (u32_t *)dst;
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while (len < outlen) {
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ret = sys_rand32_get();
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if ((outlen-len) < sizeof(ret)) {
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blocksize = len;
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(void *)memcpy(udst, &ret, blocksize);
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} else {
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(*udst++) = ret;
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}
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len += blocksize;
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}
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}
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