beam_vdif.c File Reference

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <mwalib.h>
#include <vdifio.h>
#include "vcsbeam.h"
#include "mwa_header.h"
#include "ascii_header.h"

Include dependency graph for beam_vdif.c:

Functions
void	float2int8_trunc (float *f, int n, float min, float max, int8_t *i)
	Converts floats to 8-bit integers. More...
void	vdif_write_second (struct vdifinfo *vf, vdif_header *vhdr, float *data_buffer_vdif)
	Writes a second's worth of data to a VDIF file. More...
void	vdif_write_data (struct vdifinfo *vf, int8_t *output)
	Write VDIF data to file. More...
void	vmPopulateVDIFHeader (vcsbeam_context *vm, beam_geom *beam_geom_vals, double mjd_start, double sec_offset)
	Populates a VDIF header with data derived from the observation. More...
void	to_offset_binary (int8_t *i, int n)
	Convert from two's complement to "offset binary" (??) More...

Function Documentation

float2int8_trunc()

void float2int8_trunc	(	float *	f,
		int	n,
		float	min,
		float	max,
		int8_t *	i
	)

Converts floats to 8-bit integers.

Parameters

[in]	f	The (source) buffer of floats
	n	The number of floats in f
	min	The smallest allowed float
	max	The largest allowed float
[out]	i	The (destination) buffer of 8-bit integers

to_offset_binary()

void to_offset_binary	(	int8_t *	i,
		int	n
	)

Convert from two's complement to "offset binary" (??)

Parameters

i	An array of integers to be converted
n	The number of integers in i

vdif_write_data()

void vdif_write_data	(	struct vdifinfo *	vf,
		int8_t *	output
	)

Write VDIF data to file.

Parameters

vf	A struct containing metadata about the target VDIF file
output	The buffer to be written to file

Todo:

Make sure that the header file is unneccesarily re-written each time this function is called. If so, put this bit somewhere more sensible.

vdif_write_second()

void vdif_write_second	(	struct vdifinfo *	vf,
		vdif_header *	vhdr,
		float *	data_buffer_vdif
	)

Writes a second's worth of data to a VDIF file.

Parameters

vf	A struct containing metadata about the target VDIF file
vhdr	A pointer to the VDIF frame header buffer
data_buffer_vdif	The data to be written out

The data to be written out are first normalised and scaled to fit in the range -126 to 127 and demoted to integers. "Blocks" of data are then written to file, along with the appropriate binary headers for each "frame", via the function vdif_write_data().

vmPopulateVDIFHeader()

void vmPopulateVDIFHeader	(	vcsbeam_context *	vm,
		beam_geom *	beam_geom_vals,
		double	mjd_start,
		double	sec_offset
	)

Populates a VDIF header with data derived from the observation.

Parameters

vm	The VCSBeam context struct
beam_geom_vals	A beam_geom struct containing pointing information
mjd_start	The start MJD of the observation
sec_offset	The offset from the start of the observation in seconds