[Feature request] 24-bit (3-byte) data support

[Rangi42]

RGBDS has db/rb for 8-bit bytes, dw/rw for 16-bit words, and dl/rl for 32-bit "long words". This leaves a gap for 24-bit values, which have various use cases both during assembly and runtime (bank+address, RGB888 color, any time you need "millions" of values but still with a fourth byte to spare).

Prior terminology is uncommon, since historically 24-bit machines just called these "words" (the eZ80 even referred to "16-bit words" and "24-bit words" on the same platform!), and then we settled on powers of 2 for everything. Some examples do exist:

• WLA-DX uses .DL for for 24-bit "long words", and .DD for 32-bit "double words". (But we can't use dl/rl because RGBDS's "long"s are different.)
• Wikipedia claims "The term SWORD is sometimes used to describe a 24-bit data type with the S prefix referring to 'sesqui'." (But we can't use ds/rs because ds is already a "define space" keyword. (And rs is not a keyword, but _RS is a symbol.))
• MySQL uses TINYINT, SMALLINT, MEDIUMINT, INT, and BIGINT for 1-, 2-, 3-, 4-, and 8-byte values respectively. (We could use dm/rm? Although I don't like how "rm" looks like "remove".)
• StackExchange mentions "tribyte" as a common term in some contexts. (We could use dt/rt?)
• pokecrystal uses a dt macro for three-byte big-endian values. (pret could change that to bigdt if RGBDS uses dt/rt -- frankly they should anyway, to make the endianness obvious and to match their bigdw macro.)

Overall, I'd prefer adding dt/rt keywords for "tribyte" data.

[ISSOtm]

Thank you for your research, thorough as always :)

I don't feel convinced by this feature, because the primary use case, “far pointers”, are heterogeneous and I believe that (bank, ptr) is roughly as common as (ptr, bank). And also because I have thus far never witnessed a use of dl, not even emulated by dws due to a lack of awareness.

The other use cases, I feel are niche enough to be emulated using dbs for RGB888 (db $12,$34,$56, $78,$9A,$BC is fine..? And that's assuming you want the components stored in RGB order, too; dt would give you BGR.) or warrant writing a macro.

[Rangi42]

Yeah, that's fair. Pokemon uses a few 3-byte values (e.g. for money and experience) but some of those would need a macro anyway for being big-endian or BCD, so plain dt wouldn't get much use. (Probably more than dl, but still not a lot.)