| Routine ID: M434 | |
|---|---|
| Author(s): F. Carminati, M. Jonker, J. Zoll | Library: KERNLIB, VAX and DECSTATION only |
| Submitter: | Submitted: 05.10.1987 |
| Language: Fortran or Assembler | Revised: |
These routines do VAX byte inversions 1-2-3-4 to 4-3-2-1 in each word of an array, either in-place or copied.
Structure:
SUBROUTINE subprogram
User Entry Names: VXINVB, VXINVC
Usage:
CALL VXINVB(IXV,N)inverts four bytes in each of the N words at array IXV, in-place.
CALL VXINVC(IV,IXV,N)copies the N words at array IV to array IXV, with the bytes inverted in each word.
On DEC machines bytes read from a disk file are
loaded in memory in reverse order. One of the above routines,
applied to the result of a binary read from a disk file, causes
the bytes to be stored in each 32 bits word in the same order than
in the disk file. This is useful when reading a binary file
transferred through a network from a foreign system, in order to
preserve the order of the bytes in each 32 bits word.
Please note that several network utilities include the possibility
to perform a bytes inversion in the network protocol. Note also
that when reading or writing from a magnetic tape, the bytes may be
swapped in pairs and not in groups of 4.