BEAR4 compression
From ScienceZero
WORK IN PROGRESS...
BEAR4 is designed for microcontrollers that have little RAM. It uses the data decompressed so far as the dictionary, compared to typical LZ compression this decreases efficiency since the index range must be larger and the need for storing the count. Most of the loss is recovered by only reading the number of bits required for the current index/count range.
Header
BE4R - file ID w - word size (1-64) s - symbol size (1-64) h - symbol shift (0-63) i - maximum index size (1-32) c - maximum count size (1-16)
Data
0 <symbol> 1 <index> <count>
Pseudocode
do indexSize = min(log2(decompressedSize), maximumIndexSize) countSize = min(indexSize, maximumCountSize) read classBit if classBit = 0 then read symbol output symbol else read index, count for each count read symbolFromDecompressed output symbol next endif loop