PetscBinaryWrite

Writes to a binary file.

Synopsis

PetscErrorCode PetscBinaryWrite(int fd, const void *p, PetscCount 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

Fortran Note

There are different functions for each datatype, for example PetscBinaryWriteInt()

See Also

PetscBinaryRead(), PetscBinaryOpen(), PetscBinaryClose(), PetscViewerBinaryGetDescriptor(), PetscBinarySynchronizedWrite(), PetscBinarySynchronizedRead(), PetscBinarySynchronizedSeek()

Level

advanced

Location

src/sys/fileio/sysio.c

Examples

src/vec/vec/tutorials/ex6.c
src/vec/vec/tutorials/ex6f.F90

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