var/external/bufr/irev.for

   1       FUNCTION IREV(N)
   2
   3 C$$$  SUBPROGRAM DOCUMENTATION BLOCK
   4 C
   5 C SUBPROGRAM:    IREV
   6 C   PRGMMR: WOOLLEN          ORG: NP20       DATE: 1994-01-06
   7 C
   8 C ABSTRACT: THIS FUNCTION WILL, WHEN THE LOCAL MACHINE IS "LITTLE-
   9 C   ENDIAN" (I.E., USES A RIGHT TO LEFT SCHEME FOR NUMBERING THE BYTES
  10 C   WITHIN A MACHINE WORD), RETURN A COPY OF AN INPUT INTEGER WORD WITH
  11 C   THE BYTES REVERSED.  ALTHOUGH, BY DEFINITION (WITHIN WMO MANUAL
  12 C   306), A BUFR MESSAGE IS A STREAM OF INDIVIDUAL OCTETS (I.E., BYTES)
  13 C   THAT IS INDEPENDENT OF ANY PARTICULAR MACHINE REPRESENTATION, THE
  14 C   BUFR ARCHIVE LIBRARY SOFTWARE OFTEN NEEDS TO INTERPRET ALL OR PARTS
  15 C   OF TWO OR MORE ADJACENT BYTES IN ORDER TO CONSTRUCT AN INTEGER
  16 C   WORD.  BY DEFAULT, THE SOFTWARE USES THE "BIG-ENDIAN" (LEFT TO
  17 C   RIGHT) SCHEME FOR NUMBERING BYTES.  BY REVERSING THE BYTES, IREV
  18 C   ALLOWS THE INTEGER WORD TO BE PROPERLY READ OR WRITTEN (DEPENDING
  19 C   ON WHETHER INPUT OR OUTPUT OPERATIONS, RESPECTIVELY, ARE BEING
  20 C   PERFORMED) ON LITTLE-ENDIAN MACHINES.  IF THE LOCAL MACHINE IS
  21 C   BIG-ENDIAN, IREV SIMPLY RETURNS A COPY OF THE SAME INTEGER THAT WAS
  22 C   INPUT.
  23 C
  24 C PROGRAM HISTORY LOG:
  25 C 1994-01-06  J. WOOLLEN -- ORIGINAL AUTHOR
  26 C 2003-11-04  J. ATOR    -- ADDED DOCUMENTATION
  27 C 2003-11-04  S. BENDER  -- ADDED REMARKS/BUFRLIB ROUTINE
  28 C                           INTERDEPENDENCIES
  29 C 2003-11-04  D. KEYSER  -- UNIFIED/PORTABLE FOR WRF; ADDED HISTORY
  30 C                           DOCUMENTATION
  31 C 2007-01-19  J. ATOR    -- BIG-ENDIAN VS. LITTLE-ENDIAN IS NOW
  32 C                           DETERMINED AT COMPILE TIME AND CONFIGURED
  33 C                           WITHIN BUFRLIB VIA CONDITIONAL COMPILATION
  34 C                           DIRECTIVES
  35 C
  36 C USAGE:    IREV (N)
  37 C   INPUT ARGUMENT LIST:
  38 C     N        - INTEGER: INTEGER WORD WITH BYTES ORDERED ACCORDING TO
  39 C                THE "BIG-ENDIAN" NUMBERING SCHEME
  40 C
  41 C   OUTPUT ARGUMENT LIST:
  42 C     IREV     - INTEGER: INTEGER WORD WITH BYTES ORDERED ACCORDING TO
  43 C                THE NUMBERING SCHEME OF THE LOCAL MACHINE (EITHER
  44 C                "BIG-ENDIAN" OR "LITTLE-ENDIAN", IF "BIG-ENDIAN THEN
  45 C                THIS IS JUST A DIRECT COPY OF N)
  46 C
  47 C REMARKS:
  48 C    THIS ROUTINE CALLS:        None
  49 C    THIS ROUTINE IS CALLED BY: IPKM     IUPM     PKB      PKC
  50 C                               UPBB
  51 C                               Normally not called by any application
  52 C                               programs.
  53 C
  54 C ATTRIBUTES:
  55 C   LANGUAGE: FORTRAN 77
  56 C   MACHINE:  PORTABLE TO ALL PLATFORMS
  57 C
  58 C$$$
  59
  60       COMMON /HRDWRD/ NBYTW,NBITW,IORD(8)
  61
  62       CHARACTER*8 CINT,DINT
  63       EQUIVALENCE(CINT,INT)
  64       EQUIVALENCE(DINT,JNT)
  65
  66 C----------------------------------------------------------------------
  67 C----------------------------------------------------------------------
  68
  69 #ifdef BIG_ENDIAN
  70       IREV = N
  71 #else
  72       INT = N
  73       DO I=1,NBYTW
  74         DINT(I:I) = CINT(IORD(I):IORD(I))
  75       ENDDO
  76       IREV = JNT
  77 #endif
  78
  79       RETURN
  80       END