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docs: Add random number generation to the API Reference System section

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Angus Gratton
2021-05-11 11:40:38 +10:00
parent 190063a6b3
commit e14edecf5f
8 changed files with 84 additions and 46 deletions
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29
components/bootloader_support/include/bootloader_random.h
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@@ -21,33 +21,38 @@ extern "C" {
#endif
/**
* @brief Enable early entropy source for RNG
* @brief Enable an entropy source for RNG if RF is disabled
*
* Uses the SAR ADC to feed entropy into the HWRNG. The ADC is put
* into a test mode that reads an internal reference voltage and
* constantly feeds the LSB of data into the HWRNG. Consult the
* SoC Technical Reference Manual for more information.
* 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 used from app code early during operation, if true
* random numbers are required before WiFi stack is initialised.
* Call this function from app code only if WiFi/BT are not yet
* enabled and I2S and ADC are not in use.
*
* Call bootloader_random_disable() when done.
* random numbers are required before RF is initialised. Consult
* ESP-IDF Programming Guide "Random Number Generation" section for
* details.
*/
void bootloader_random_enable(void);
/**
* @brief Disable early entropy source for RNG
* @brief Disable entropy source for RNG
*
* Disables SAR ADC source and resets the I2S hardware.
* Disables internal entropy source. Must be called after
* bootloader_random_enable() and before RF 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
*/