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Make MicroBit::seedRandom a public function with 2 variants.

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seedRandom() seeds from the hardware RNG, whilst seedRandom(uint32_t)
seeds from the given 32-bit number.
This commit is contained in:
Damien George 2016-01-25 15:13:12 +00:00 committed by James Devine
parent d22a36fdd5
commit 3160ba6268
2 changed files with 80 additions and 14 deletions
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23
inc/MicroBit.h
View file

@ -62,7 +62,6 @@ class MicroBit
{
private:
void seedRandom();
void compassCalibrator(MicroBitEvent e);
uint32_t randomValue;
@ -182,6 +181,28 @@ class MicroBit
*/
int sleep(int milliseconds);
/**
* Seed the pseudo random number generator using the hardware generator.
*
* Example:
* @code
* uBit.seedRandom();
* @endcode
*/
void seedRandom();
/**
* Seed the pseudo random number generator using the given value.
*
* @param seed The 32-bit value to seed the generator with.
*
* Example:
* @code
* uBit.seedRandom(0x12345678);
* @endcode
*/
void seedRandom(uint32_t seed);
/**
* Generate a random number in the given range.
* We use the NRF51822 in built random number generator here

71
source/MicroBit.cpp
View file

@ -1,5 +1,26 @@
/*
* The underlying Nordic libraries that support BLE do not compile cleanly with the stringent GCC settings we employ
* If we're compiling under GCC, then we suppress any warnings generated from this code (but not the rest of the DAL)
* The ARM cc compiler is more tolerant. We don't test __GNUC__ here to detect GCC as ARMCC also typically sets this
* as a compatability option, but does not support the options used...
*/
#if !defined(__arm)
#pragma GCC diagnostic ignored "-Wunused-function"
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
#endif
#include "MicroBit.h"
#include "nrf_soc.h"
/*
* Return to our predefined compiler settings.
*/
#if !defined(__arm)
#pragma GCC diagnostic pop
#endif
/**
* custom function for panic for malloc & new due to scoping issue.
*/
@ -85,7 +106,8 @@ MicroBit::MicroBit() :
MICROBIT_ID_IO_P12,MICROBIT_ID_IO_P13,MICROBIT_ID_IO_P14,
MICROBIT_ID_IO_P15,MICROBIT_ID_IO_P16,MICROBIT_ID_IO_P19,
MICROBIT_ID_IO_P20),
bleManager()
bleManager(),
ble(NULL)
{
}
@ -433,22 +455,45 @@ void MicroBit::seedRandom()
{
randomValue = 0;
// Start the Random number generator. No need to leave it running... I hope. :-)
NRF_RNG->TASKS_START = 1;
for(int i = 0; i < 4 ;i++)
if(uBit.ble)
{
// Clear the VALRDY EVENT
NRF_RNG->EVENTS_VALRDY = 0;
// If Bluetooth is enabled, we need to go through the Nordic software to safely do this.
uint32_t result = sd_rand_application_vector_get((uint8_t*)&randomValue, sizeof(randomValue));
// Wait for a number ot be generated.
while ( NRF_RNG->EVENTS_VALRDY == 0);
randomValue = (randomValue << 8) | ((int) NRF_RNG->VALUE);
// If we couldn't get the random bytes then at least make the seed non-zero.
if (result != NRF_SUCCESS)
randomValue = 0xBBC5EED;
}
else
{
// Othwerwise we can access the hardware RNG directly.
// Disable the generator to save power.
NRF_RNG->TASKS_STOP = 1;
// Start the Random number generator. No need to leave it running... I hope. :-)
NRF_RNG->TASKS_START = 1;
for(int i = 0; i < 4; i++)
{
// Clear the VALRDY EVENT
NRF_RNG->EVENTS_VALRDY = 0;
// Wait for a number ot be generated.
while(NRF_RNG->EVENTS_VALRDY == 0);
randomValue = (randomValue << 8) | ((int) NRF_RNG->VALUE);
}
// Disable the generator to save power.
NRF_RNG->TASKS_STOP = 1;
}
}
/**
* Seed our pseudo random number generator (PRNG) using the given 32-bit value.
*/
void MicroBit::seedRandom(uint32_t seed)
{
randomValue = seed;
}