GY-63_MS5611/libraries/UUID/UUID.cpp
2022-11-27 09:39:34 +01:00

114 lines
2.4 KiB
C++

//
// FILE: UUID.cpp
// AUTHOR: Rob Tillaart
// VERSION: 0.1.4
// DATE: 2022-06-14
// PURPOSE: Arduino Library for generating UUID's
// URL: https://github.com/RobTillaart/UUID
// https://en.wikipedia.org/wiki/Universally_unique_identifier
#include "UUID.h"
UUID::UUID()
{
seed(1, 2);
setVariant4Mode();
generate();
}
void UUID::seed(uint32_t s1, uint32_t s2)
{
// set Marsaglia constants, prevent 0 as value
if (s1 == 0) s1 = 1;
if (s2 == 0) s2 = 2;
_m_w = s1;
_m_z = s2;
}
// check version 0.1.1 for more readable code
void UUID::generate()
{
uint32_t ar[4];
for (uint8_t i = 0; i < 4; i++)
{
ar[i] = _random();
// store binary version globally ?
// _ar[i] = ar[i];
}
// Conforming to RFC 4122 Specification
// - byte 7: four most significant bits ==> 0100 --> always 4
// - byte 9: two most significant bits ==> 10 --> always {8, 9, A, B}.
//
// patch bits for version 1 and variant 4 here
if (_mode == UUID_MODE_VARIANT4)
{
ar[1] &= 0xFFF0FFFF; // remove 4 bits.
ar[1] |= 0x00040000; // variant 4
ar[2] &= 0xFFFFFFF3; // remove 2 bits
ar[2] |= 0x00000008; // version 1
}
// process 16 bytes build up the char array.
for (uint8_t i = 0, j = 0; i < 16; i++)
{
// multiples of 4 between 8 and 20 get a -.
// but note we are doing 2 digits in one loop.
if ((i & 0x1) == 0)
{
if ((4 <= i) && (i <= 10)) _buffer[j++] = '-';
}
// process one byte at the time instead of a nibble
uint8_t nr = i / 4;
uint8_t xx = ar[nr];
uint8_t ch = xx & 0x0F;
_buffer[j++] = (ch < 10) ? '0' + ch : ('a' - 10) + ch;
ch = (xx >> 4) & 0x0F;
ar[nr] >>= 8;
_buffer[j++] = (ch < 10) ? '0' + ch : ('a' - 10) + ch;
}
_buffer[36] = 0;
}
char * UUID::toCharArray()
{
return _buffer;
}
//////////////////////////////////////////////////
//
// PRINTING
//
size_t UUID::printTo(Print& p) const
{
return p.print(_buffer);
};
//////////////////////////////////////////////////
//
// RANDOM GENERATOR MARSAGLIA
//
// An example of a simple pseudo-random number generator is the
// Multiply-with-carry method invented by George Marsaglia.
// two initializers (not null)
uint32_t UUID::_random()
{
_m_z = 36969L * (_m_z & 65535L) + (_m_z >> 16);
_m_w = 18000L * (_m_w & 65535L) + (_m_w >> 16);
return (_m_z << 16) + _m_w; /* 32-bit result */
}
// -- END OF FILE --