1 // Copyright 2010-2016 Espressif Systems (Shanghai) PTE LTD 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #pragma once 16 17 #include <stddef.h> 18 19 #ifdef __cplusplus 20 extern "C" { 21 #endif 22 23 /** 24 * @brief Enable early entropy source for RNG 25 * 26 * Uses the SAR ADC to feed entropy into the HWRNG. The ADC is put 27 * into a test mode that reads the 1.1V internal reference source and 28 * feeds the LSB of data into the HWRNG. 29 * 30 * Can also be used from app code early during operation, if entropy 31 * is required before WiFi stack is initialised. Call this function 32 * from app code only if WiFi/BT are not yet enabled and I2S and SAR 33 * ADC are not in use. 34 * 35 * Call bootloader_random_disable() when done. 36 */ 37 void bootloader_random_enable(void); 38 39 /** 40 * @brief Disable early entropy source for RNG 41 * 42 * Disables SAR ADC source and resets the I2S hardware. 43 * 44 */ 45 void bootloader_random_disable(void); 46 47 /** 48 * @brief Fill buffer with 'length' random bytes 49 * 50 * @param buffer Pointer to buffer 51 * @param length This many bytes of random data will be copied to buffer 52 */ 53 void bootloader_fill_random(void *buffer, size_t length); 54 55 #ifdef __cplusplus 56 } 57 #endif 58