/[MITgcm]/MITgcm/eesupp/src/exch_cycle_ebl.F
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revision 1.2 by cnh, Sun Feb 4 14:38:43 2001 UTC revision 1.3 by cnh, Fri Sep 21 03:54:34 2001 UTC
# Line 1  Line 1 
1  C $Header$  C $Header$
2  C $Name$  C $Name$
3    
4    CBOP
5    C     !ROUTINE: EXCH_CYCLE_EBL
6    
7    C     !INTERFACE:
8        SUBROUTINE EXCH_CYCLE_EBL( myThid )        SUBROUTINE EXCH_CYCLE_EBL( myThid )
 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     \==========================================================/  
9        IMPLICIT NONE        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 ==  C     == Global data ==
35  #include "SIZE.h"  #include "SIZE.h"
36  #include "EEPARAMS.h"  #include "EEPARAMS.h"
37  #include "EESUPPORT.h"  #include "EESUPPORT.h"
38  #include "EXCH.h"  #include "EXCH.h"
39    
40    C     !INPUT PARAMETERS:
41  C     == Routine arguments ==  C     == Routine arguments ==
42  C     myThid - Thread number of this instance of the routine  C     myThid :: Thread number of this instance of the routine
43        INTEGER myThid        INTEGER myThid
44    
45    C     !LOCAL VARIABLES:
46  C     == Local variables ==  C     == Local variables ==
47  C     bi, bj - Loop counters  C     bi, bj :: Loop counters
48        INTEGER bi, bj        INTEGER bi, bj
49    CEOP
50    
51        DO bj=myByLo(myThid),myByHi(myThid)        DO bj=myByLo(myThid),myByHi(myThid)
52         DO bi=myBxLo(myThid),myBxHi(myThid)         DO bi=myBxLo(myThid),myBxHi(myThid)
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