This is the native binary format of DisPerSE. Functions for reading and writing NDfield format in C can be found within the file ${DISPERSE_SRC}/src/C/NDfield.c (see functions Load_NDfield and Save_NDfield).

When using the C functions from Disperse, data is loaded into the following C structure which is close to the actual structure of the file (see file ${DISPERSE_SRC}/src/C/NDfield.h):

#define ND_CHAR   (1<<0)
#define ND_UCHAR  (1<<1)
#define ND_SHORT  (1<<2)
#define ND_USHORT (1<<3)
#define ND_INT    (1<<4)
#define ND_UINT   (1<<5)
#define ND_LONG   (1<<6)
#define ND_ULONG  (1<<7)
#define ND_FLOAT  (1<<8)
#define ND_DOUBLE (1<<9)

typedef struct NDfield_str
{
 char comment[80];  // a comment on the data
 int dims[NDFIELD_MAX_DIMS];  // dimensions of the grid, must be [ndims,nparticles] when data represents sample particles coordinates (i.e. when fdims_index!=0)
 int ndims;  // number of dimensions of the space
 int n_dims;  // number of meaningfull values in dims array
 int fdims_index; // if 0, the field is a regular grid of dimensions dims, else the file contains the dims[0] coordinates of dims[1] particles.
 int datatype;  // type of the data (one of the ND_... defined above)
 double x0[NDFIELD_MAX_DIMS];  // origin of the bounding box
 double delta[NDFIELD_MAX_DIMS];  // extent of the bounding box
 char dummy[160];  // dummy data, for future extensions or for storing anything you want.

 void *val;  // pointer to data

 long nval;  // total number of particles (fdims_index==1) or pixels (fdims_index==0)
 int datasize;  // size in bytes of datatype type.
} NDfield;

The NDfield binary format is organized as follows (blocks are delimited by dummy variables indicating the size of the blocks for FORTRAN compatibility, but they are ignored in C):