Random Number Generator

Hi,

here is a first prototype of the RNG as a C module:

\#include "jswrap_rng.h"  // We need the declaration of the jswrap_rng_random function
\#include "jsinteractive.h" // Pull in the jsiConsolePrint function

// Let's define the JavaScript class that will contain our `random()` methods. We'll call it `RNG`
/*JSON{
  "type" : "class",
  "class" : "RNG"
}*/

// Now, we define the `jswrap_rng_random` to be a `staticmethod` on the `RNG` class
/*JSON{
  "type" : "staticmethod",
  "class" : "RNG",
  "name" : "random",
  "generate" : "jswrap_rng_random",
  "return" : ["JsVar","The random number or NAN, if it is not supported on the platform."]
}*/

// Now, we define the `jswrap_rng_random_long` to be a `staticmethod` on the `RNG` class
/*JSON{
  "type" : "staticmethod",
  "class" : "RNG",
  "name" : "random_long",
  "generate" : "jswrap_rng_random_long",
  "return" : ["JsVar","The random number or NAN, if it is not supported on the platform."]
}*/

// TODO: We need a better way to pull this in! This will not work on all boards. And we need
// to make the jshAnalogRead function non-static where it is defined.
extern int jshAnalogRead(JsvPinInfoAnalog analog, bool fastConversion);

static int get_bit() {
  jshDelayMicroseconds(10);
  int v = jshAnalogRead(JSH_ANALOG1 | JSH_ANALOG_CH17, false);
  // It seems the lower 4 bits are always zero.
  v >>= 4;
  v &= 1;
  return v;
}

static long long rng_random() {
\#if defined(STM32F1) || defined(STM32F4)
  // enable sensor
  ADC_TempSensorVrefintCmd(ENABLE);

  long long sum = 0;
  int s;
  int v1 = get_bit();
  for (s = 0; s < 32; s++)
  {
    int v2 = get_bit();
    sum <<= 1;
    if (v1 != v2)
       sum++;
    v1 = v2;
  }

  // disable sensor
  ADC_TempSensorVrefintCmd(DISABLE);
  return sum;
\#else
  return NAN;
\#endif
}

JsVar *jswrap_rng_random_long() {
\#if defined(STM32F1) || defined(STM32F4)
  long long v = rng_random();
  return jsvNewFromLongInteger(v);
\#else
  return jsNewFromFloat(NAN);
\#endif
}

JsVar *jswrap_rng_random() {
\#if defined(STM32F1) || defined(STM32F4)
  long long v = rng_random();
  double value = ((double)(v)) / 4294967296.0;
  return jsvNewFromFloat(value);
\#else
  return jsNewFromFloat(NAN);
\#endif
}

Seems to work fine. But there are some flaws: Namely it pulls in some function from the hardware abstraction layer. I had to make the function non-static there. I am not sure what the best way would be to do this. Add the function to the hardware layer itself? Add a function which takes the analog reading as an int?