GY-63_MS5611/libraries/Adler

Adler

Arduino Library for Adler-32 checksum

Description

This library provides a Adler checksum of a data array.

Relates to https://github.com/RobTillaart/CRC

Relates to https://github.com/RobTillaart/Fletcher

Tested on Arduino UNO only.

Interface

Adler class

Use #include "Adler.h"

• Adler32() Constructor, initializes internals.
• void begin(uint8_t s1 = 1, uint8_t s2 = 0) resets the internals. optional setting start values for s1 and s2. Note this is not part of the standard. This allows a restart from a specific index in a buffer.
• void add(uint8_t value) add a single value to the checksum.
• void add(const uint8_t * array, uint8_t length) add an array of values to the checksum.
• uint32_t getAdler() get the current checksum.
• uint32_t count() get the number of items added. Merely a debugging feature, can overflow without affecting checksum.

The class is typically used for streaming very large blocks of data, optional with intermediate checksum tests.

Performance

Not tested ESP32 (and many other platforms) yet. First numbers of .add(value) measured with test sketch shows the following timing.

Checksum	UNO 16 MHz	ESP32 240 MHz
Adler32	5.6 us

Interface static functions

The function is straightforward.

Use #include "Adler.h"

• uint32_t adler32(uint8_t *data, uint16_t length) length in units of 1 byte = 8 bits.

The function is typically used for an in memory buffer to calculate the Adler checksum once.

Performance

Not tested extensively, first numbers of .add(array, length) measured with Adler_performance.ino sketch shows the following timing.

Lorem Ipsum text = 868 bytes.

Checksum	UNO 16 MHz	ESP32 240 MHz
Adler32	1116 us

Average 1116 / 868 = 1.29 us per byte.

Operation

See examples.

Future ideas

• test other platforms
• optimize add(array, length) ..