esp-idf/components/bootloader_support/include/bootloader_random.h
2022-04-11 10:55:28 +08:00

61 lines
1.8 KiB
C

/*
* SPDX-FileCopyrightText: 2010-2021 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#pragma once
#include <stddef.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Enable an entropy source for RNG if RF subsystem is disabled
*
* @warning This function is not safe to use if any other subsystem is accessing the RF subsystem or
* the ADC at the same time!
*
* The exact internal entropy source mechanism depends on the chip in use but
* all SoCs use the SAR ADC to continuously mix random bits (an internal
* noise reading) into the HWRNG. Consult the SoC Technical Reference
* Manual for more information.
*
* Can also be called from app code, if true random numbers are required without initialized RF subsystem.
* This might be the case in early startup code of the application when the RF subsystem has not
* started yet or if the RF subsystem should not be enabled for power saving.
*
* Consult ESP-IDF Programming Guide "Random Number Generation" section for
* details.
*/
void bootloader_random_enable(void);
/**
* @brief Disable entropy source for RNG
*
* Disables internal entropy source. Must be called after
* bootloader_random_enable() and before RF subsystem features, ADC, or
* I2S (ESP32 only) are initialized.
*
* Consult the ESP-IDF Programming Guide "Random Number Generation"
* section for details.
*/
void bootloader_random_disable(void);
/**
* @brief Fill buffer with 'length' random bytes
*
* @note If this function is being called from app code only, and never
* from the bootloader, then it's better to call esp_fill_random().
*
* @param buffer Pointer to buffer
* @param length This many bytes of random data will be copied to buffer
*/
void bootloader_fill_random(void *buffer, size_t length);
#ifdef __cplusplus
}
#endif