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Annotation of 42BSD/ingres/source/libq/IIpb_read.c, revision 1.1

1.1     ! root        1: # include      <ingres.h>
        !             2: # include      "IIglobals.h"
        !             3: # include      <sccs.h>
        !             4: 
        !             5: SCCSID(@(#)IIpb_read.c 7.1     2/5/81)
        !             6: 
        !             7: 
        !             8: /*
        !             9: **  IIPB_READ -- read a pipe block
        !            10: **
        !            11: **     This routine reads a pipe block into *ppb.  It also handles
        !            12: **     all the low level protocol: RESET blocks, SYNC blocks, META
        !            13: **     blocks, blocks intended for another process, etc.
        !            14: **
        !            15: **     When this routine returns, it returns with a block intended
        !            16: **     for this process, which must be a REGULAR block, a RESPONSE
        !            17: **     block, or an ERROR block.
        !            18: **
        !            19: **     Parameters:
        !            20: **             ppb -- a pointer to the area which wants the block.
        !            21: **
        !            22: **     Returns:
        !            23: **             none
        !            24: **
        !            25: **     Side Effects:
        !            26: **             ppb is set to the named block.
        !            27: **             Virtually any amount of stuff can happen, depending
        !            28: **                     on what is coming through the pipe.
        !            29: **
        !            30: **     Trace Flags:
        !            31: **             12.4 - 12.9
        !            32: */
        !            33: 
        !            34: 
        !            35: IIpb_read(ppb)
        !            36: register pb_t  *ppb;
        !            37: {
        !            38:        register int    type;
        !            39:        register int    from;
        !            40: 
        !            41:        /*
        !            42:        **  Top Loop.
        !            43:        **      Hang waiting for a normal block.  Other blocks are
        !            44:        **              handled inside the loop.
        !            45:        **      We multiplex 'from' in here temporarily.
        !            46:        */
        !            47: 
        !            48:        for (;;)
        !            49:        {
        !            50:                from = IIpb_rphys(ppb, IIinput);
        !            51: 
        !            52:                if (from != PB_IOSIZE)
        !            53:                        IIsyserr("pb_read: read error (%d)", from);
        !            54: 
        !            55:                /* set up buffer pointers, etc. */
        !            56:                ppb->pb_xptr = ppb->pb_data;
        !            57:                ppb->pb_nleft = ppb->pb_nused;
        !            58:                type = ppb->pb_type;
        !            59:                from = ppb->pb_from;
        !            60: 
        !            61:                /* do sync block processing */
        !            62:                if (type == PB_SYNC)
        !            63:                {
        !            64:                        IISyncs[from]--;
        !            65:                        continue;
        !            66:                }
        !            67: 
        !            68:                /* see if we are ignoring from this process */
        !            69:                if (IISyncs[from] > 0)
        !            70:                        continue;
        !            71: 
        !            72:                /*
        !            73:                **  Block type dispatching.
        !            74:                **      Regular, response, and error blocks return.
        !            75:                **      Meta blocks are handled by calling other
        !            76:                **              routines.
        !            77:                */
        !            78: 
        !            79:                switch (type)
        !            80:                {
        !            81:                  case PB_REG:
        !            82:                  case PB_RESP:
        !            83:                  case PB_ERR:
        !            84:                        /* handled by readinput() */
        !            85:                        return;
        !            86: 
        !            87:                  /* insert more meta handling before this line */
        !            88: 
        !            89:                  default:
        !            90:                        IIsyserr("pb_read: type %d", type);
        !            91:                }
        !            92:        }
        !            93: }

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