Since the trick works on mantissa only without hidden 1 included, I wonder if that number of bits in mantissa was chosen because of it

Link to Mark Owen’s excellent QFP library for soft float on Cortex-M0+ (ARMv6-M) and Cortex-M3/M4 (ARMv7-M).

https://www.quinapalus.com/qfplib.html

Nice write up here, too, I like the idea of a firm float.

I appreciate this warning near the top: This post contains floating point. Floating point is known to the State of California to cause confusion and a fear response in mammalian bipeds.

I wisely hit the back button :)