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README_HEADER.rst

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Blosc Header Format

Blosc (as of Version 1.0.0) has the following 16 byte header that stores information about the compressed buffer:

|-0-|-1-|-2-|-3-|-4-|-5-|-6-|-7-|-8-|-9-|-A-|-B-|-C-|-D-|-E-|-F-|
  ^   ^   ^   ^ |     nbytes    |   blocksize   |    ctbytes    |
  |   |   |   |
  |   |   |   +--typesize
  |   |   +------flags
  |   +----------versionlz
  +--------------version

Datatypes of the Header Entries

All entries are little endian.

version:

uint8
versionlz:

uint8
flags (bitfield):
bit 0 (0x01):whether the shuffle filter has been applied or not
bit 1 (0x02):whether the internal buffer is a pure memcpy or not
typesize:

uint8
nbytes:

uint32
blocksize:

uint32
ctbytes:

uint32