https://github.com/ped7g/ZXSpectrumN...acked.i.asm#L3

There was some ongoing discussion about packing 5bit 0..31 values (aka "strings" with limited charset) to bitstream, and how long the decoding routine has to be.
From the initial 22B by Busy we went down to 19B (thanks to Baze and Zilog), and I collected it all into my "code snippets" project (it's targetting ZX Next, but the particular 5b-decoding is classic Z80 only).

There's also sjasmplus macro to encode regular string literals... I'm so glad I did add WHILE in v1.18.0 ... it's becoming really handy (I could used `DUP inputdata_size` in this case too, but WHILE reads better to me, to understand what is happening).

Have fun. (I have some suspicion this is "old news" for you, but consider there are many newcomers trying to learn Z80 programming, the snippets are targetting those, as examples of small routines)