fz::FZMHeaderCore Struct Reference

Fixed-size FZM file header core (80 bytes). More...

#include <fzm_format.h>

Public Member Functions
uint64_t	computeHeaderSize () const

Public Attributes
uint32_t	magic
	Must equal FZM_MAGIC (4B)
uint16_t	version
	FZM_VERSION (2B)
uint16_t	num_buffers
	Number of FZMBufferEntry records (2B)
uint64_t	uncompressed_size
	Sum of all source uncompressed sizes in bytes (8B)
uint64_t	compressed_size
	Total compressed payload size in bytes (8B)
uint64_t	header_size
	Total header size; compressed payload starts at this offset (8B)
uint32_t	num_stages
	Number of FZMStageInfo records (4B)
uint16_t	num_sources
	Number of source (input) stages in the pipeline (2B)
uint16_t	flags
	Feature flags: FZM_FLAG_* constants (2B)
uint64_t	source_uncompressed_sizes [FZM_MAX_SOURCES]
	(32B)
uint32_t	data_checksum
	CRC32 of compressed payload (v3.1+; 0 if flag not set) (4B)
uint32_t	header_checksum
	CRC32 of header bytes (v3.1+; 0 if flag not set) (4B)

Detailed Description

Fixed-size FZM file header core (80 bytes).

Followed on disk by FZMStageInfo[num_stages] then FZMBufferEntry[num_buffers], then the compressed payload at byte offset header_size.

Checksums (v3.1+):

• data_checksum: CRC32 (IEEE 802.3) of the compressed payload bytes.
• header_checksum: CRC32 of the full header (core + stage array + buffer array) with header_checksum zeroed during computation. Both are 0 when the corresponding FZM_FLAG_HAS_* bit is not set in flags.

Member Function Documentation

computeHeaderSize()

uint64_t fz::FZMHeaderCore::computeHeaderSize ( ) const

inline

Total header size in bytes (core + stage array + buffer array).

Member Data Documentation

source_uncompressed_sizes

uint64_t fz::FZMHeaderCore::source_uncompressed_sizes[FZM_MAX_SOURCES]

(32B)

Per-source uncompressed sizes in forward topological source-discovery order (same order as the InputSpec vector passed to compress()). Indices 0..num_sources-1 are valid.