A promising 32-bit checksum

A project log for PEAC Pisano with End-Around Carry algorithm

Add X to Y and Y to X, says the song. And carry on.

Yann Guidon / YGDESYann Guidon / YGDES 04/16/2021 at 04:360 Comments

The last log Periodicity has found an amazing property of the 2×16 configuration with carry: The period is 2³¹+32767, instead of 1,5×2¹⁶ ... Enabling the carry thrusts the checksum in a new dimension that Adler or Fletcher can't contemplate. There are still weird questions to address but let's first define this new design.

The dataflow graph is almost like before BUT the whole width of the register is used (unless the register is too wide and the values MUST be truncated).

It appears that the graph should be reorganised :-)

The JS code runs 6.5B loops and its length is usually 2147516415, or 2³¹+32767. The behaviour is quite confusing and the orbit(s) must be now analysed...