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