GPT4_Entropy.cpp

//GPT-4 refactoring Walter Anderson's Entropy.cpp library. 
//Please note that you need to handle any exceptions thrown in the code, such as `std::invalid_argument`. Since Arduino doesn't support exceptions by //default due to the memory footprint, you might need to find an alternate way to handle the error. If you decide to use exceptions, you'll need to enable //them in your compiler settings.

#include <Arduino.h>
#include <Entropy.h>

constexpr uint8_t WDT_MAX_8INT = 0xFF;
constexpr uint16_t WDT_MAX_16INT = 0xFFFF;
constexpr uint32_t WDT_MAX_32INT = 0xFFFFFFFF;

#ifndef ARDUINO_SAM_DUE
 constexpr uint8_t gWDT_buffer_SIZE = 32;
 constexpr uint8_t WDT_POOL_SIZE = 8;
 uint8_t gWDT_buffer[gWDT_buffer_SIZE];
 uint8_t gWDT_buffer_position = 0;
 uint8_t gWDT_loop_counter = 0;
 volatile uint8_t gWDT_pool_start = 0;
 volatile uint8_t gWDT_pool_end = 0;
 volatile uint8_t gWDT_pool_count = 0;
 volatile uint32_t gWDT_entropy_pool[WDT_POOL_SIZE];
#endif

// This function initializes the global variables needed to implement the circular entropy pool and
// the buffer that holds the raw Timer 1 values that are used to create the entropy pool.
void EntropyClass::Initialize(void)
{
  // Code removed for brevity
}

uint32_t EntropyClass::random(void)
{
#ifdef ARDUINO_SAM_DUE
  while (! (TRNG->TRNG_ISR & TRNG_ISR_DATRDY));
  retVal = TRNG->TRNG_ODATA;
#else
  while (gWDT_pool_count < 1);
  ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
  {
    retVal = gWDT_entropy_pool[gWDT_pool_start];
    gWDT_pool_start = (gWDT_pool_start + 1) % WDT_POOL_SIZE;
    --gWDT_pool_count;
  }
#endif
  return retVal;
}

uint8_t EntropyClass::random8(void)
{
  static uint8_t byte_position = 0;
  uint8_t retVal8;

  if (byte_position == 0)
    share_entropy.int32 = random();
  retVal8 = share_entropy.int8[byte_position++];
  byte_position %= 4;
  return retVal8;
}

uint16_t EntropyClass::random16(void)
{
  static uint8_t word_position = 0;
  uint16_t retVal16;

  if (word_position == 0)
    share_entropy.int32 = random();
  retVal16 = share_entropy.int16[word_position++];
  word_position %= 2;
  return retVal16;
}

uint32_t EntropyClass::random(uint32_t max)
{
  uint32_t slice;

  if (max < 2)
    retVal = 0;
  else
    {
      retVal = WDT_MAX_32INT;
      // Code removed for brevity
    }
  return retVal;
}

uint32_t EntropyClass::random(uint32_t min, uint32_t max)
{
  uint32_t tmp_random, tmax;

  tmax = max - min;
  if (tmax < 1)
    retVal = min;
  else
    {
      tmp_random = random(tmax);
      retVal = min + tmp_random;
    }
  return retVal;
}

// Remaining functions left out for brevity...

#ifndef ARDUINO_SAM_DUE
static void isr_hardware_neutral(uint8_t val)
{
  // Code removed for brevity...
}
#endif

#if defined( __AVR_ATtiny25__ ) || defined( __AVR_ATtiny45__ ) || defined( __AVR_ATtiny85__ )
ISR(WDT_vect)
{
  isr_hardware_neutral(TCNT0);
}

#elif defined(__AV
R__)
ISR(WDT_vect)
{
isr_hardware_neutral(TCNT1L);
}
#endif

#ifndef ARDUINO_SAM_DUE
void wdt_init(void) attribute((naked)) attribute((section(".init3")));

void wdt_init(void)
{
// Code removed for brevity...
}
#endif

EntropyClass Entropy;