Incorrect roundtrip for [blosc2.Filter.BITSHUFFLE, blosc2.Filter.BYTEDELTA]

[froody]

Describe the bug
When invoked from python with a random uint16 array with max value of 118, the roundtrip for bitshuffle + bytedelta is incorrect, even though they are correct on their own.

To Reproduce

import numpy as np
import blosc2
np.random.seed(0)

a = np.random.randint(118, size=13058819, dtype=np.uint16)

def test_filters(a, filters):
    c = blosc2.pack_array2(a, cparams={"filters":filters})
    u = blosc2.unpack_array2(c)
    if not np.array_equal(a, u):
        print("Error: arrays are not equal with", filters)

test_filters(a, [blosc2.Filter.BITSHUFFLE, blosc2.Filter.BYTEDELTA])
test_filters(a, [blosc2.Filter.BITSHUFFLE])
test_filters(a, [blosc2.Filter.BYTEDELTA])
test_filters(a, [blosc2.Filter.SHUFFLE, blosc2.Filter.BYTEDELTA])

Expected behavior
(nothing printed)

Logs
Error: arrays are not equal with [<Filter.BITSHUFFLE: 2>, <Filter.BYTEDELTA: 34>]

System information:

• OS: [Ubuntu 22.04
• Compiler: n/a
• Version: 2.2.4

Additional context
Add any other context about the problem here.

[froody]

Repro in C:

• Run with no args to exhibit failure
• Run with any arg to show successfull roundtrip with SHUFFLE + BYTEDELTA

#include <stdio.h>
#include <blosc2.h>
#include "blosc2/filters-registry.h"

#define NCHUNKS 1
#define NTHREADS 2
#define TYPESIZE 2
#define LEN 13058819
#define CHUNKSIZE (TYPESIZE * LEN)

int main(int argc, char **argv) {
  blosc2_init();
  uint16_t *ref_data = (uint16_t *)malloc(CHUNKSIZE);
  std::srand(0);
  for (int i = 0; i < LEN; i++) {
    ref_data[i] = std::rand() / (RAND_MAX / 118);
  }
  uint16_t *data_dest = (uint16_t *)malloc(CHUNKSIZE);
  int32_t isize = CHUNKSIZE;
  blosc2_cparams cparams = BLOSC2_CPARAMS_DEFAULTS;
  cparams.compcode = BLOSC_ZSTD;
  if (argc > 1) {
    cparams.filters[BLOSC2_MAX_FILTERS - 2] = BLOSC_SHUFFLE;
  } else {
    cparams.filters[BLOSC2_MAX_FILTERS - 2] = BLOSC_BITSHUFFLE;
  }
  cparams.filters[BLOSC2_MAX_FILTERS - 1] = BLOSC_FILTER_BYTEDELTA;
  cparams.filters_meta[BLOSC2_MAX_FILTERS - 1] = 7;

  blosc2_dparams dparams = BLOSC2_DPARAMS_DEFAULTS;
  blosc2_schunk* schunk;

  /* Create a super-chunk container */
  cparams.typesize = TYPESIZE;
  cparams.nthreads = NTHREADS;
  dparams.nthreads = NTHREADS;
  char *urlpath = (char *)"/tmp/dir1.b2frame";
  blosc2_storage storage = {.contiguous=false, .urlpath=urlpath, .cparams=&cparams, .dparams=&dparams};

  if (true) {
    /* Remove the directory and write new data */
    blosc2_remove_dir(storage.urlpath);
    schunk = blosc2_schunk_new(&storage);
    blosc2_schunk_append_buffer(schunk, ref_data, isize);
  }

  /* Read the chunks that were written before */
  schunk = blosc2_schunk_open(urlpath);
  blosc2_schunk_decompress_chunk(schunk, 0, data_dest, isize);
  for (int i = 0; i < LEN; i++) {
    if (data_dest[i] != ref_data[i]) {
      printf("Decompressed data differs from original %d, %d, %d!\n",
             LEN, ref_data[i], data_dest[i]);
      return -1;
    }
  }

  printf("Successful roundtrip data <-> schunk !\n");

  /* Remove directory */
  blosc2_remove_dir(storage.urlpath);
  /* Free resources */
  /* Destroy the super-chunk */
  blosc2_schunk_free(schunk);
  blosc2_destroy();
  return 0;
}

[FrancescAlted]

Fixed in #530. Thanks @froody !