VDIFIO

VDIFIO is a library to create, access and modify headers for VDIF formatted data. Documentation for the VDIF standard is available at:

http://www.vlbi.org/vdif/

int createVDIFHeader(vdif_header *header, int framelength, int threadid,  int bits, int nchan,
                     int iscomplex, char stationid[3]);

Populate the values for a vdif header. Memory is assume to have been prellocated. All time values (e.g. Epoch) are set to zero - they need to be set seperately

Function to completely fill header struct, returns non-zero on error */

int getVDIFThreadID(vdif_header *header);

Return the thread ID

int getVDIFFrameBytes(vdif_header *header);

Return the number of bytes occupied by the entire VDIF frame (note internally VDIF divides this values by 8)

int getVDIFFrameMJD(vdif_header *header);

Return the MJD daynumber of the current VDIF frame (incorporating the current Epoch plus seconds of offset from Epoch).

int getVDIFFrameSecond(vdif_header *header);

Return the current number of seconds since 00:00UT for the current VDIF frame time (essentially seconds%86400)

double getVDIFDMJD(vdif_header *header, int framepersec);

Return the MJD daynumber and fraction of the current VDIF frame (incorporating the current Epoch plus seconds of offset from Epoch).

int getVDIFFrameNumber(vdif_header *header);

Return the current VDIF frame number

int getVDIFStationID(vdif_header *header);

Return the VDIF station ID

int getVDIFBitsPerSample(vdif_header *header);

Return the number of bits per sample (note VDIF internally encodes this -1)

int getVDIFNumChannels(vdif_header *header);

Return the number of channels in the data array. Not VDIF encodes this internally as a power of 2

int getVDIFFrameInvalid(vdif_header *header);

Return the VDIF frame validity bit

int getVDIFFullSecond(vdif_header *header);

Return the number of seconds since VDIF Epoch

int getVDIFEpoch(vdif_header *header);

Return the VDIF Epoch

/* Functions to set just one value from a raw header */

void setVDIFFrameMJD(vdif_header *header, int framemjd);

Set …

void setVDIFMJDSec(vdif_header *header, uint64_t mjdsec);

Set …

void setVDIFFrameSecond(vdif_header *header, int framesecond);

Set the VDIF header seconds from epoch.

void setVDIFFrameNumber(vdif_header *header, int framenumber);

Set the VDIF header frame number

void setVDIFFrameInvalid(vdif_header *header, unsigned int invalid);

Set the header validity bit to 0 or 1.

void setVDIFFrameBytes(vdif_header *header, int bytes);

Set the frame size in bytes (internally VDIF stores this a number of 8byte words).

void setVDIFNumChannels(vdif_header *header, int numchannels);

Set the freame number of channels. Internally VDIF stores this as a power of 2.

void setVDIFThreadID(vdif_header *header, int threadid);

Set the frame thread ID.

int setVDIFTime(vdif_header *header, time_t time);

Set the VDIF seconds since epoch to the passed time (in Unix Epoch). Assume the Epoch has been set appropriately.

void setVDIFEpoch(vdif_header *header, int mjd);

Set the VDIF Epoch to the nearest MJD earlier than the passed MJD daynumer.

int nextVDIFHeader(vdif_header *header, int framepersec);

Increment the VDIF frame number, incrementing seconds since Epoch as appropriate. framepersec needs to be passed to correctly wrap the frame counter.