fec.h File Reference

Macros
#define	FEC_HEADER_SIZE   32
#define	FEC_MAGIC   0xFECC0DEC

Functions
int	fec_new (int k, int n, struct fec_parms **parms)
void	fec_free (struct fec_parms *p)
void	fec_encode (struct fec_parms *parms, const unsigned char *const *src, unsigned char *dst, int idx, int sz)
int	fec_decode (struct fec_parms *parms, unsigned char **data, int *idx, int sz)

Macro Definition Documentation

FEC_HEADER_SIZE

#define FEC_HEADER_SIZE   32

Each FEC slice contains a FEC header of this size.

FEC_MAGIC

#define FEC_MAGIC   0xFECC0DEC

The FEC header starts with this magic value.

Function Documentation

fec_new()

int fec_new	(	int	k,
		int	n,
		struct fec_parms **	result
	)

Create a new encoder and return an opaque descriptor to it.

Parameters

k	Number of input slices.
n	Number of output slices.
result	On success the Fec descriptor is returned here.

Returns

Standard.

This creates the k*n encoding matrix. It is computed starting with a Vandermonde matrix, and then transformed into a systematic matrix.

fec_free()

void fec_free

(

struct fec_parms *

p

)

Deallocate a fec params structure.

Parameters

p	The structure to free.

fec_encode()

void fec_encode	(	struct fec_parms *	parms,
		const unsigned char *const *	src,
		unsigned char *	dst,
		int	idx,
		int	sz
	)

Compute one encoded slice of the given input.

Parameters

parms	The fec parameters returned earlier by fec_new().
src	The k data slices to encode.
dst	Result pointer.
idx	The index of the slice to compute.
sz	The size of the input data packets.

Encode the k slices of size sz given by src and store the output slice number idx in dst.

fec_decode()

int fec_decode	(	struct fec_parms *	parms,
		unsigned char **	data,
		int *	idx,
		int	sz
	)

Decode one slice from the group of received slices.

Parameters

parms	Pointer to fec params structure.
data	Pointers to received packets.
idx	Pointer to packet indices (gets modified).
sz	Size of each packet.

Returns

Zero on success, -1 on errors.

The data vector of received slices and the indices of slices are used to produce the correct output slice. The data slices are modified in-place.