irev.F File Reference

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Functions/Subroutines
function	irev (N)
	THIS FUNCTION WILL, WHEN THE LOCAL MACHINE IS "LITTLE- ENDIAN" (I.E., USES A RIGHT TO LEFT SCHEME FOR NUMBERING THE BYTES WITHIN A MACHINE WORD), RETURN A COPY OF AN INPUT INTEGER WORD WITH THE BYTES REVERSED. More...

Detailed Description

Author

WOOLLEN

Date

1994-01-06

Definition in file irev.F.

Function/Subroutine Documentation

function irev

(

N

)

THIS FUNCTION WILL, WHEN THE LOCAL MACHINE IS "LITTLE- ENDIAN" (I.E., USES A RIGHT TO LEFT SCHEME FOR NUMBERING THE BYTES WITHIN A MACHINE WORD), RETURN A COPY OF AN INPUT INTEGER WORD WITH THE BYTES REVERSED.

ALTHOUGH, BY DEFINITION (WITHIN WMO MANUAL 306), A BUFR MESSAGE IS A STREAM OF INDIVIDUAL OCTETS (I.E., BYTES) THAT IS INDEPENDENT OF ANY PARTICULAR MACHINE REPRESENTATION, THE BUFR ARCHIVE LIBRARY SOFTWARE OFTEN NEEDS TO INTERPRET ALL OR PARTS OF TWO OR MORE ADJACENT BYTES IN ORDER TO CONSTRUCT AN INTEGER WORD. BY DEFAULT, THE SOFTWARE USES THE "BIG-ENDIAN" (LEFT TO RIGHT) SCHEME FOR NUMBERING BYTES. BY REVERSING THE BYTES, IREV ALLOWS THE INTEGER WORD TO BE PROPERLY READ OR WRITTEN (DEPENDING ON WHETHER INPUT OR OUTPUT OPERATIONS, RESPECTIVELY, ARE BEING PERFORMED) ON LITTLE-ENDIAN MACHINES. IF THE LOCAL MACHINE IS BIG-ENDIAN, IREV SIMPLY RETURNS A COPY OF THE SAME INTEGER THAT WAS INPUT.

PROGRAM HISTORY LOG: 1994-01-06 J. WOOLLEN – ORIGINAL AUTHOR 2003-11-04 J. ATOR – ADDED DOCUMENTATION 2003-11-04 S. BENDER – ADDED REMARKS/BUFRLIB ROUTINE INTERDEPENDENCIES 2003-11-04 D. KEYSER – UNIFIED/PORTABLE FOR WRF; ADDED HISTORY DOCUMENTATION 2007-01-19 J. ATOR – BIG-ENDIAN VS. LITTLE-ENDIAN IS NOW DETERMINED AT COMPILE TIME AND CONFIGURED WITHIN BUFRLIB VIA CONDITIONAL COMPILATION DIRECTIVES

USAGE: IREV (N) INPUT ARGUMENT LIST: N - INTEGER: INTEGER WORD WITH BYTES ORDERED ACCORDING TO THE "BIG-ENDIAN" NUMBERING SCHEME

OUTPUT ARGUMENT LIST: IREV - INTEGER: INTEGER WORD WITH BYTES ORDERED ACCORDING TO THE NUMBERING SCHEME OF THE LOCAL MACHINE (EITHER "BIG-ENDIAN" OR "LITTLE-ENDIAN", IF "BIG-ENDIAN THEN THIS IS JUST A DIRECT COPY OF N)

REMARKS: THIS ROUTINE CALLS: None THIS ROUTINE IS CALLED BY: IPKM IUPM PKB PKC UPBB Normally not called by any application programs.

Definition at line 50 of file irev.F.

Referenced by ipkm(), iupm(), pkb(), pkc(), and upbb().