esp-idf/components/esp_hw_support/include/esp_random.h

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/*
* SPDX-FileCopyrightText: 2021 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
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#pragma once
#include <stddef.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Get one random 32-bit word from hardware RNG
*
* If Wi-Fi or Bluetooth are enabled, this function returns true random numbers. In other
* situations, if true random numbers are required then consult the ESP-IDF Programming
* Guide "Random Number Generation" section for necessary prerequisites.
*
* This function automatically busy-waits to ensure enough external entropy has been
* introduced into the hardware RNG state, before returning a new random number. This delay
* is very short (always less than 100 CPU cycles).
*
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* @return Random value between 0 and UINT32_MAX
*/
uint32_t esp_random(void);
/**
* @brief Fill a buffer with random bytes from hardware RNG
*
* @note This function is implemented via calls to esp_random(), so the same
* constraints apply.
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*
* @param buf Pointer to buffer to fill with random numbers.
* @param len Length of buffer in bytes
*/
void esp_fill_random(void *buf, size_t len);
#ifdef __cplusplus
}
#endif