hash_128_above can only cover half string for hash compute

static LJ_NOINLINE uint32_t hash_128_above(uint64_t seed, const char* str,
					   uint32_t len)
{
  uint32_t chunk_num, chunk_sz, chunk_sz_log2, i, pos1, pos2;
  uint64_t h1, h2, v;
  const char* chunk_ptr;

  chunk_num = 16;
  chunk_sz = len / chunk_num;
  chunk_sz_log2 = log2_floor(chunk_sz);

  pos1 = get_random_pos_unsafe(chunk_sz_log2, 0);
  pos2 = get_random_pos_unsafe(chunk_sz_log2, 1);

  h1 = lj_crc32_u32(0, len ^ seed);
  h2 = 0;

  /* loop over 14 chunks, 2 chunks at a time */
  for (i = 0, chunk_ptr = str; i < (chunk_num / 2 - 1);
       chunk_ptr += chunk_sz, i++) {

    v = *cast_uint64p(chunk_ptr + pos1);
    h1 = lj_crc32_u64(h1, v);

    v = *cast_uint64p(chunk_ptr + chunk_sz + pos2);
    h2 = lj_crc32_u64(h2, v);
  }

every loop just move one chunk，it's a bug here? the loop only cover half string
should we set chunk_ptr += 2*chunk_sz
#60

Start at the hash_128_above entry point and inspect how chunk_ptr advances through the loop and how its callers use the computed hash. Verify coverage with strings large enough to produce multiple chunks, then confirm the corrected traversal preserves expected hash results and does not read beyond the input.