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Annotation of researchv10no/ipc/mgrs/ndkmgr/dkwindow.h, revision 1.1.1.1

1.1       root        1: /*  URP window-size negotiation.
                      2:  *
                      3:  *  The 16 bits of the window-size argument are defined as:
                      4:  *
                      5:  *  -----------------------------------------------------------------
                      6:  *  |valid|   spare   |   originator   |   destination  |   traffic |
                      7:  *  |     |           |   window size  |   window size  |           |
                      8:  *  -----------------------------------------------------------------
                      9:  *     1        3              4                4              4
                     10:  *
                     11:  *  The "valid" bit equals 1 to indicate that the window size values
                     12:  *  are specified.  Zero means they should be ignored and that default
                     13:  *  values must be used instead.  Old controllers that do not have
                     14:  *  window size negotiation happen to set this bit to zero, fortunately.
                     15:  *
                     16:  *  The actual window size is computed from the 4-bit window size 
                     17:  *  parameter (n) as 2**(n+4).  Thus, window sizes range from 16 to
                     18:  *  512K bytes.
                     19:  *
                     20:  *  The originator of a call sets his "originator window size" to be
                     21:  *  less than or equal to the size of his receive buffer, and he
                     22:  *  requests through the "destination window size" the size of the
                     23:  *  buffer that he would like to use for transmission.  As the call
                     24:  *  is being set up, trunk processes and the destination line process
                     25:  *  may lower either or both window sizes.  The resulting window sizes
                     26:  *  are returned to the originator in the call ANSWER message.
                     27:  */
                     28: 
                     29: #ifndef MIN
                     30: #define MIN(x,y)  (x < y ? x : y)
                     31: #endif
                     32: /* Format originator, destination, and traffic values */
                     33: #define WINDOW(o,d,t)  ((o<<8) | (d<<4) | t | 0100000)
                     34: 
                     35: #define W_VALID(x)  (x & 0100000)
                     36: 
                     37: #define W_ORIG(x)  ((x>>8) & 017)
                     38: 
                     39: #define W_DEST(x)  ((x>>4) & 017)
                     40: 
                     41: #define W_TRAF(x)  (x & 017)
                     42: 
                     43: #define W_DESTMAX(x,y)  (WINDOW(W_ORIG(x),MIN(W_DEST(x),y),W_TRAF(x)))
                     44: 
                     45: #define W_LIMIT(x,y)  (WINDOW(MIN(W_ORIG(x),y),MIN(W_DEST(x),y),W_TRAF(x)))
                     46: 
                     47: #define        W_VALUE(x)      (1<<(x+4))
                     48: 
                     49: 
                     50: #define WS_16  0
                     51: #define WS_32  1
                     52: #define WS_64  2
                     53: #define WS_128 3
                     54: #define WS_256 4
                     55: #define WS_512 5
                     56: #define WS_1K  6
                     57: #define WS_2K  7
                     58: #define WS_4K  8
                     59: #define WS_8K  9
                     60: #define WS_16K 10
                     61: #define WS_32K 11
                     62: #define WS_64K 12
                     63: #define WS_128K        13
                     64: #define WS_256K        14
                     65: #define WS_512K        15

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