eesupp/src/exch_cycle_ebl.F

C $Header: /u/gcmpack/models/MITgcmUV/eesupp/src/exch_cycle_ebl.F,v 1.2 2001/02/04 14:38:43 cnh Exp $
C $Name:  $

CBOP
C     !ROUTINE: EXCH_CYCLE_EBL

C     !INTERFACE:
      SUBROUTINE EXCH_CYCLE_EBL( myThid )
      IMPLICIT NONE

C     !DESCRIPTION:
C     *==========================================================*
C     | SUBROUTINE EXCH_CYCLE_EBL                                 
C     | o Cycle exchange buffer level.                            
C     *==========================================================*
C     | Step the "exchange buffer level" to next value.           
C     | The buffer level is used to prevent consecutive messages  
C     | overwriting one another. Because we know that every tile  
C     | will participate in an exchange we can be sure that every 
C     | tile will cycle through the buffers with the same         
C     | sequence. Also we know that a tile cannot start a new     
C     | exchange before it has completed its end of the previous  
C     | exchange. Thus by cycling through three buffer levels we  
C     | can be sure that the buffer we write to will be free.     
C     |  That is by the time we are participating in the third    
C     | exchange transaction we know that both ends of the first  
C     | transaction must have completed.                          
C     | Note --                                                   
C     | 1. We allow more than three levels below although this    
C     | is not necessary.                                         
C     *==========================================================*

C     !USES:
C     == Global data ==
#include "SIZE.h"
#include "EEPARAMS.h"
#include "EESUPPORT.h"
#include "EXCH.h"

C     !INPUT PARAMETERS:
C     == Routine arguments ==
C     myThid :: Thread number of this instance of the routine
      INTEGER myThid

C     !LOCAL VARIABLES:
C     == Local variables ==
C     bi, bj :: Loop counters
      INTEGER bi, bj
CEOP

      DO bj=myByLo(myThid),myByHi(myThid)
       DO bi=myBxLo(myThid),myBxHi(myThid)
C--     Use next level exchange buffer in cycle.
        exchangeBufLevel(1,bi,bj) = exchangeBufLevel(1,bi,bj)+1
        IF ( exchangeBufLevel(1,bi,bj) .GT. NUMBER_OF_BUFFER_LEVELS )
     &   exchangeBufLevel(1,bi,bj) = 1
       ENDDO
      ENDDO

      RETURN
      END
1	C $Header: /u/gcmpack/models/MITgcmUV/eesupp/src/exch_cycle_ebl.F,v 1.2 2001/02/04 14:38:43 cnh Exp $
2	C $Name: $
3
4	CBOP
5	C !ROUTINE: EXCH_CYCLE_EBL
6
7	C !INTERFACE:
8	SUBROUTINE EXCH_CYCLE_EBL( myThid )
9	IMPLICIT NONE
10
11	C !DESCRIPTION:
12	C ==========================================================
13	C \| SUBROUTINE EXCH_CYCLE_EBL
14	C \| o Cycle exchange buffer level.
15	C ==========================================================
16	C \| Step the "exchange buffer level" to next value.
17	C \| The buffer level is used to prevent consecutive messages
18	C \| overwriting one another. Because we know that every tile
19	C \| will participate in an exchange we can be sure that every
20	C \| tile will cycle through the buffers with the same
21	C \| sequence. Also we know that a tile cannot start a new
22	C \| exchange before it has completed its end of the previous
23	C \| exchange. Thus by cycling through three buffer levels we
24	C \| can be sure that the buffer we write to will be free.
25	C \| That is by the time we are participating in the third
26	C \| exchange transaction we know that both ends of the first
27	C \| transaction must have completed.
28	C \| Note --
29	C \| 1. We allow more than three levels below although this
30	C \| is not necessary.
31	C ==========================================================
32
33	C !USES:
34	C == Global data ==
35	#include "SIZE.h"
36	#include "EEPARAMS.h"
37	#include "EESUPPORT.h"
38	#include "EXCH.h"
39
40	C !INPUT PARAMETERS:
41	C == Routine arguments ==
42	C myThid :: Thread number of this instance of the routine
43	INTEGER myThid
44
45	C !LOCAL VARIABLES:
46	C == Local variables ==
47	C bi, bj :: Loop counters
48	INTEGER bi, bj
49	CEOP
50
51	DO bj=myByLo(myThid),myByHi(myThid)
52	DO bi=myBxLo(myThid),myBxHi(myThid)
53	C-- Use next level exchange buffer in cycle.
54	exchangeBufLevel(1,bi,bj) = exchangeBufLevel(1,bi,bj)+1
55	IF ( exchangeBufLevel(1,bi,bj) .GT. NUMBER_OF_BUFFER_LEVELS )
56	& exchangeBufLevel(1,bi,bj) = 1
57	ENDDO
58	ENDDO
59
60	RETURN
61	END