dranke/upkr
1
0
Fork 0
mirror of https://github.com/exoticorn/upkr.git synced 2026-01-20 11:36:42 +01:00
Code Issues Projects Releases Wiki Activity

z80_unpacker: readme.txt and comment update

Browse Source
This commit is contained in:
Peter Helcmanovsky (Ped)
2022-09-19 15:19:39 +02:00
parent 9913dcf4bb
commit 8a32e1384c
2 changed files with 18 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
z80_unpacker/readme.txt
View File

@@ -10,10 +10,23 @@ may be incompatible with files you will produce with current version)
Asm syntax is z00m's sjasmplus: https://github.com/z00m128/sjasmplus
Backward direction unpacker added as compile-time option, see example for both forward/backward
depacker in action.
The packed/unpacked data-overlap has to be tested per-case, in worst case the packed data
may need even more than 7 bytes to unpack final byte, but usually 1-4 bytes may suffice.
TODO:
- build base corpus of test data to benchmark future changes in algorithm/format
- review first implementation to identify weak spots where the implementation can be shorter+faster
with acceptable small changes to the format
- review non-bitstream variant, if it's feasible to try to implement it with Z80
- build bigger corpus of test data to benchmark future changes in algorithm/format (example and zx48.rom was used to do initial tests)
- maybe try to beat double-loop `decode_number` with different encoding format
- (@ped7g) Z80N version of unpacker for ZX Next devs
- (@exoticorn) add Z80 specific packer (to avoid confusion with original MicroW8 variant), and land it all to master branch, maybe in "z80" directory or something? (and overall decide how to organise+merge this upstream into main repo)
- (@exoticorn) add to packer output with possible packed/unpacked region overlap
DONE:
* review non-bitstream variant, if it's feasible to try to implement it with Z80
- Ped7g: IMHO nope, the 12b x 8b MUL code would probably quickly cancel any gains from the simpler state update
* review first implementation to identify weak spots where the implementation can be shorter+faster
with acceptable small changes to the format
- Ped7g: the decode_bit settled down and now doesn't feel so confused and redundant, the code seems pretty on point to me, no obvious simplification from format change
- Ped7g: the decode_number double-loop is surprisingly resilient, especially in terms of code size I failed to beat it, speed wise only negligible gains

2
z80_unpacker/unpack.asm
View File

@@ -4,7 +4,7 @@
;; initial version by Peter "Ped" Helcmanovsky (C) 2022, licensed same as upkr project ("unlicensed")
;; to assemble use z00m's sjasmplus: https://github.com/z00m128/sjasmplus
;;
;; you can define UPKR_PROBS_ORIGIN to specific 256 byte aligned address for probs array (386 bytes),
;; you can define UPKR_PROBS_ORIGIN to specific 256 byte aligned address for probs array (320 bytes),
;; otherwise it will be positioned after the unpacker code (256 aligned)
;;
;; public API: