Uncorrect compression (or decompression) for some lengths not divisible by 8 bytes

[byphilipp]

Describe the bug The result of compression and decompression with filters=[blosc2.Filter.SHUFFLE, blosc2.Filter.BYTEDELTA] for some lengths not divisible by 8 bytes is not equvivalent: the last byte is differs

To Reproduce

import blosc2
import numpy as np
dtype = np.float32
for N in range(100,270):
    x = np.random.rand(N).astype(dtype)
    kw=dict(
            clevel=5,
#            filters=[blosc2.Filter.SHUFFLE], # correct
#            filters=[blosc2.Filter.BYTEDELTA], # correct
#            filters=[blosc2.Filter.BYTEDELTA, blosc2.Filter.SHUFFLE], # correct
             filters=[blosc2.Filter.SHUFFLE, blosc2.Filter.BYTEDELTA], # uncorrect !
    )
    y = np.frombuffer( blosc2.decompress2 (blosc2.compress2(np.frombuffer(x, dtype=np.uint8).copy(order='C'), codec=blosc2.Codec.ZSTD, **kw)), dtype=dtype)
    #y = np.frombuffer( np.frombuffer(x, dtype=np.uint8), dtype=dtype)
    if y[-1]-x[-1] != 0:
        print(f"{N=} {y[-1]-x[-1]}")

output:

N=195 -0.1865813434123993
N=223 -0.20511126518249512
N=225 2.6814947806386197e+37
N=227 -0.2120416760444641
N=229 1.0758920518724525e+25
N=235 -0.8137646317481995
N=237 -0.5785623788833618
N=239 -445465753550848.0
N=241 344564.53125
N=247 -6.356997702928093e+27
N=249 6891780.0
N=251 -0.4392470419406891
N=253 -1.2648026543392063e+29
N=257 -101628403712.0
N=259 56037704.0
N=261 -0.7367768287658691
N=263 -0.5903393626213074
N=265 -0.5874314308166504
N=267 -0.1973332017660141
N=269 -0.1740696132183075

Expected behavior Empty output

Desktop (please complete the following information):

• OS: Ubuntu 22.04
• Python 3.11
• blosc2 - I try 3.0.0, 2.7.1, 2.6.2 and see this problem in all versions

[FrancescAlted]

I suppose the issue should be in the C-Blosc2 side. Would you like to investigate more there?