PetscBinaryWrite#

Writes to a binary file.

Synopsis#

PetscErrorCode PetscBinaryWrite(int fd, const void *p, PetscInt n, PetscDataType type)

Not Collective

Input Parameters#

fd - the file
p - the buffer, an array of the type that matches the value in type
n - the number of items to write
type - the type of items to read (PETSC_INT, PETSC_REAL or PETSC_SCALAR)

Notes#

PetscBinaryWrite() uses byte swapping to work on all machines; the files are written using big-endian ordering to the file. On little-endian machines the numbers are converted to the big-endian format when they are written to disk. When PETSc is configured using ./configure with --with-64-bit-indices the integers are written to the file as 64-bit integers, this means they can only be read back in when the option --with-64-bit-indices is used.

If running with __float128 precision the output of PETSC_REAL is in __float128 unless one uses the -binary_write_double option

The buffer p should be read-write buffer, and not static data. This way, byte-swapping is done in-place, and then the buffer is written to the file.

This routine restores the original contents of the buffer, after it is written to the file. This is done by byte-swapping in-place the second time.

Because byte-swapping may be done on the values in data it cannot be declared const