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https://github.com/RobTillaart/Arduino.git
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82 lines
1.5 KiB
C++
82 lines
1.5 KiB
C++
//
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// FILE: Fletcher32.cpp
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// AUTHOR: Rob Tillaart, Daniel Mohr
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// PURPOSE: Arduino class for Fletcher32
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// URL: https://github.com/RobTillaart/Fletcher
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#include "Fletcher32.h"
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// UINT16_MAX = 65535UL = ((((uint32_t) 1) << 16) - 1)
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#define FLETCHER_32 UINT16_MAX
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Fletcher32::Fletcher32()
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{
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begin();
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}
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void Fletcher32::begin(uint16_t s1, uint16_t s2)
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{
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_s1 = (s1 == FLETCHER_32) ? 0 : s1;
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_s2 = (s2 == FLETCHER_32) ? 0 : s2;
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_count = 0;
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}
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void Fletcher32::add(uint16_t value)
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{
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_count++;
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#ifdef ARDUINO_ARCH_AVR
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unsigned int t = _s1;
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// Serial.println("__builtin_uadd_overflow");
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if (__builtin_uadd_overflow(t, value, &t)) {
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t++;
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}
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_s1 = t;
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t = _s2;
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if (__builtin_uadd_overflow(t, _s1, &t)) {
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t++;
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}
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_s2 = t;
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#elif defined(ARDUINO_ARCH_SAMD) || defined(ESP32) || defined(ESP8266)
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_s1 += value;
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_s1 = (_s1 & FLETCHER_32) + (_s1 >> 16);
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_s2 += _s1;
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_s2 = (_s2 & FLETCHER_32) + (_s2 >> 16);
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#else
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_s1 += value;
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if (_s1 >= FLETCHER_32) _s1 -= FLETCHER_32;
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_s2 += _s1;
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if (_s2 >= FLETCHER_32) _s2 -= FLETCHER_32;
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#endif
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}
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// NOTE: padding with zero's error
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//
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void Fletcher32::add(const uint16_t * array, uint16_t length)
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{
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while (length--)
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{
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add(*array++);
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}
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}
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uint32_t Fletcher32::getFletcher()
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{
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if (_s1 >= FLETCHER_32) _s1 -= FLETCHER_32;
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if (_s2 >= FLETCHER_32) _s2 -= FLETCHER_32;
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return (((uint32_t)_s2) << 16) | _s1;
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};
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uint32_t Fletcher32::count()
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{
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return _count;
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};
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// -- END OF FILE --
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