zstd_decompress.c File Reference

#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "zstd_decompress.h"

Data Structures
struct	ostream_t
struct	istream_t
struct	HUF_dtable
	Structure containing all tables necessary for efficient Huffman decoding. More...
struct	FSE_dtable
	The tables needed to decode FSE encoded streams. More...
struct	frame_header_t
struct	frame_context_t
	The context needed to decode blocks in a frame. More...
struct	dictionary_s
struct	sequence_command_t
struct	sequence_states_t
	The combination of FSE states needed to decode sequences. More...

Macros
#define	ZSTD_MAGIC_NUMBER   0xFD2FB528U
#define	ZSTD_BLOCK_SIZE_MAX   ((size_t)128 * 1024)
#define	MAX_LITERALS_SIZE   ZSTD_BLOCK_SIZE_MAX
#define	MAX(a, b)
#define	MIN(a, b)
#define	MESSAGE(...)
#define	ERROR(s)
#define	INP_SIZE()
#define	OUT_SIZE()
#define	CORRUPTION()
#define	BAD_ALLOC()
#define	IMPOSSIBLE()
#define	HUF_MAX_BITS   (16)
#define	HUF_MAX_SYMBS   (256)
#define	FSE_MAX_ACCURACY_LOG   (15)
#define	FSE_MAX_SYMBS   (256)
#define	DICT_SIZE_ERROR()
#define	NULL_SRC()

Enumerations
enum	seq_part_t { seq_literal_length = 0 , seq_offset = 1 , seq_match_length = 2 }
	Different modes to signal to decode_seq_tables what to do. More...
enum	seq_mode_t { seq_predefined = 0 , seq_rle = 1 , seq_fse = 2 , seq_repeat = 3 }

Functions
size_t	ZSTD_decompress (void *const dst, const size_t dst_len, const void *const src, const size_t src_len)
size_t	ZSTD_decompress_with_dict (void *const dst, const size_t dst_len, const void *const src, const size_t src_len, dictionary_t *parsed_dict)
size_t	ZSTD_get_decompressed_size (const void *src, const size_t src_len)
dictionary_t *	create_dictionary (void)
void	free_dictionary (dictionary_t *const dict)
	Free an allocated dictionary.
void	parse_dictionary (dictionary_t *const dict, const void *src, size_t src_len)

Macro Definition Documentation

BAD_ALLOC

#define BAD_ALLOC

(

)

Value:

ERROR("Memory allocation error")

CORRUPTION

#define CORRUPTION

(

)

Value:

ERROR("Corruption detected while decompressing")

DICT_SIZE_ERROR

#define DICT_SIZE_ERROR

(

)

Value:

ERROR("Dictionary size cannot be less than 8 bytes")

ERROR

#define ERROR

(

s

)

Value:

    do {                                                                       \
        MESSAGE("Error: %s\n", s);                                     \
        exit(1);                                                               \
    } while (0)

This decoder calls exit(1) when it encounters an error, however a production library should propagate error codes

FSE_MAX_ACCURACY_LOG

#define FSE_MAX_ACCURACY_LOG   (15)

For more description of FSE see https://github.com/Cyan4973/FiniteStateEntropy/

FSE_MAX_SYMBS

#define FSE_MAX_SYMBS   (256)

HUF_MAX_BITS

#define HUF_MAX_BITS   (16)

HUF_MAX_SYMBS

#define HUF_MAX_SYMBS   (256)

IMPOSSIBLE

#define IMPOSSIBLE

(

)

Value:

ERROR("An impossibility has occurred")

INP_SIZE

#define INP_SIZE

(

)

Value:

    ERROR("Input buffer smaller than it should be or input is "                \
          "corrupted")

MAX

#define MAX	(		a,
			b )

Value:

((a) > (b) ? (a) : (b))

MAX_LITERALS_SIZE

#define MAX_LITERALS_SIZE   ZSTD_BLOCK_SIZE_MAX

MESSAGE

#define MESSAGE

(

...

)

Value:

fprintf(stderr, "" __VA_ARGS__)

MIN

#define MIN	(		a,
			b )

Value:

((a) < (b) ? (a) : (b))

NULL_SRC

#define NULL_SRC

(

)

Value:

ERROR("Tried to create dictionary with pointer to null src");

OUT_SIZE

#define OUT_SIZE

(

)

Value:

ERROR("Output buffer too small for output")

ZSTD_BLOCK_SIZE_MAX

#define ZSTD_BLOCK_SIZE_MAX   ((size_t)128 * 1024)

ZSTD_MAGIC_NUMBER

#define ZSTD_MAGIC_NUMBER   0xFD2FB528U

Zstandard educational decoder implementation See https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md

Enumeration Type Documentation

seq_mode_t

enum seq_mode_t

Enumerator
seq_predefined
seq_rle
seq_fse
seq_repeat

seq_part_t

enum seq_part_t

Different modes to signal to decode_seq_tables what to do.

Enumerator
seq_literal_length
seq_offset
seq_match_length

Function Documentation

create_dictionary()

dictionary_t * create_dictionary

(

void

)

free_dictionary()

void free_dictionary

(

dictionary_t *const

dict

)

Free an allocated dictionary.

parse_dictionary()

void parse_dictionary	(	dictionary_t *const	dict,
		const void *	src,
		size_t	src_len )

ZSTD_decompress()

size_t ZSTD_decompress	(	void *const	dst,
		const size_t	dst_len,
		const void *const	src,
		const size_t	src_len )

Zstandard decompression functions. dst must point to a space at least as large as the reconstructed output.

For the case where the decompression library hasn't been included we add a dummy function to fake the process and stop the buffers being optimised out.

ZSTD_decompress_with_dict()

size_t ZSTD_decompress_with_dict	(	void *const	dst,
		const size_t	dst_len,
		const void *const	src,
		const size_t	src_len,
		dictionary_t *	parsed_dict )

If dict != NULL and dict_len >= 8, does the same thing as ZSTD_decompress but uses the provided dict

ZSTD_get_decompressed_size()

size_t ZSTD_get_decompressed_size	(	const void *	src,
		const size_t	src_len )

Get the decompressed size of an input stream so memory can be allocated in advance. This implementation assumes src points to a single ZSTD-compressed frame