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https://github.com/RobTillaart/Arduino.git
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97 lines
1.6 KiB
C++
97 lines
1.6 KiB
C++
#pragma once
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//
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// FILE: Adler.h
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// AUTHOR: Rob Tillaart
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// VERSION: 0.1.0
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// DATE: 2022-01-27
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// PURPOSE: Arduino Library for calculating Adler-32 checksum
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// URL: https://github.com/RobTillaart/Adler
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// https://en.wikipedia.org/wiki/Adler-32
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//
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// HISTORY
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// 0.1.0 2022-01-27 initial version
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#include "Arduino.h"
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#define ADLER_LIB_VERSION (F("0.1.0"))
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const uint16_t ADLER_MOD_PRIME = 65521;
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/////////////////////////////////////////////////
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//
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// STATIC FUNCTION
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//
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uint32_t adler32(uint8_t *data, uint16_t length)
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{
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uint32_t s1 = 1;
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uint32_t s2 = 0;
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for (uint16_t i = 0; i < length;)
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{
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// if S2 is halfway it is time to do modulo
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while ((i < length) && (s2 < 2147483648ULL))
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{
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s1 += data[i++];
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s2 += s1;
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}
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s1 %= ADLER_MOD_PRIME;
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s2 %= ADLER_MOD_PRIME;
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}
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return (s2 << 16) | s1;
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}
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/////////////////////////////////////////////////
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//
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// CLASS VERSION
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//
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class Adler32
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{
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public:
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Adler32()
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{
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begin(1, 0);
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}
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void begin(uint32_t s1 = 1, uint32_t s2 = 0)
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{
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_s1 = s1;
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_s2 = s2;
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_count = 0;
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}
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void add(uint8_t value)
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{
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_count++;
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_s1 += value;
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if (_s1 >= ADLER_MOD_PRIME) _s1 -= ADLER_MOD_PRIME;
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_s2 += _s1;
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if (_s2 >= ADLER_MOD_PRIME) _s2 -= ADLER_MOD_PRIME;
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}
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void add(uint8_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 getAdler() { return (_s2 << 16) | _s1; };
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uint32_t count() { return _count; };
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private:
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uint32_t _s1;
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uint32_t _s2;
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uint32_t _count;
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};
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// -- END OF FILE --
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