Hawkynt

ZX0

LZ77 compressor for 8-bit targets designed by Einar Saukas. Uses only three block types (literal, last-offset match, new-offset match) distinguished by a single context-dependent bit, with interlaced Elias gamma coding for offsets and lengths.

Properties

Property	Value
Category	Compression Algorithms
Sub-category	Dictionary-based
Security status	Not classified
Complexity	Advanced
Inventor	Einar Saukas
Year	2021
Origin	🇧🇷 Brazil
Source	algorithms/compression/zx0.js

Security

Status: not classified — treat as unverified.

No vulnerabilities are recorded for this implementation.

Documentation

• ZX0 official repository
• ZX0 README (format overview)

References

• dzx0_standard.asm reference decompressor
• Reference compress.c

Test vectors

4 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.

Vector 1 — Empty input

Field	Value
input	(empty)
expected	00000000

Vector 2 — Highly repetitive input (64 ‘A’ bytes)

Field	Value
roundTripOnly	Yes
input	41414141414141414141414141414141 41414141414141414141414141414141 41414141414141414141414141414141 41414141414141414141414141414141
expected	(empty)

Vector 3 — Text sample

Field	Value
roundTripOnly	Yes
input	74686520717569636b2062726f776e20 666f78206a756d7073206f7665722074 6865206c617a7920646f672e20746865 20717569636b2062726f776e20666f78 2e
expected	(empty)

Vector 4 — Repetitive text beyond a single maximum-length match (90 KB)

Field	Value
roundTripOnly	Yes
input	74686520717569636b2062726f776e20 666f78206a756d7073206f7665722074 6865206c617a7920646f672e20746865 20717569636b2062726f776e20666f78 … (90000 bytes; the full value is in the source)
expected	(empty)

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