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Annotation of 42BSD/ingres/source/ctlmod/pb_get.c, revision 1.1

1.1     ! root        1: # include      "ctlmod.h"
        !             2: # include      "pipes.h"
        !             3: # include      <sccs.h>
        !             4: 
        !             5: SCCSID(@(#)pb_get.c    7.1     2/5/81)
        !             6: 
        !             7: /*
        !             8: **  PB_GET -- buffered get from pipe
        !             9: **
        !            10: **     This routine just gets a record from the pipe block, reading
        !            11: **     if necessary.  It tries to do things in big chunks to keep
        !            12: **     the overhead down.
        !            13: **
        !            14: **     Parameters:
        !            15: **             ppb -- a pointer to the pipe block to unbuffer.
        !            16: **             dp -- a pointer to the data area.
        !            17: **             len -- the number of bytes to read.
        !            18: **
        !            19: **     Returns:
        !            20: **             The number of bytes actually read.
        !            21: **             Zero on end of file.
        !            22: **
        !            23: **     Side Effects:
        !            24: **             none.
        !            25: **
        !            26: **     Trace Flags:
        !            27: **             18.1 - 18.7
        !            28: */
        !            29: 
        !            30: pb_get(ppb, dp, len)
        !            31: register pb_t  *ppb;
        !            32: char           *dp;
        !            33: register int   len;
        !            34: {
        !            35:        int             rct;
        !            36:        register int    i;
        !            37: 
        !            38:        rct = 0;
        !            39: # ifdef xCTR2
        !            40:        if (tTf(18, 1))
        !            41:                lprintf("pb_get: ");
        !            42: # endif
        !            43: 
        !            44:        /*
        !            45:        **  Top Loop.
        !            46:        **      As long as we still want more, keep buffering out.
        !            47:        */
        !            48: 
        !            49:        while (len > 0)
        !            50:        {
        !            51:                /* if we have no data, read another block */
        !            52:                while (ppb->pb_nleft <= 0)
        !            53:                {
        !            54:                        if (bitset(PB_EOF, ppb->pb_stat))
        !            55:                        {
        !            56: # ifdef xCTR2
        !            57:                                if (tTf(18, 1))
        !            58:                                        printf("EOF\n");
        !            59: # endif
        !            60:                                if (rct != 0)
        !            61:                                        syserr("pb_get: EOF");
        !            62:                                return (rct);
        !            63:                        }
        !            64:                        pb_read(ppb);
        !            65:                }
        !            66: 
        !            67:                /*
        !            68:                **  Compute the length to move.
        !            69:                **      This is the min of the amount we want and the
        !            70:                **      amount we have available to us in the buffer.
        !            71:                */
        !            72: 
        !            73:                i = min(ppb->pb_nleft, len);
        !            74:                bmove(ppb->pb_xptr, dp, i);
        !            75:                ppb->pb_xptr += i;
        !            76:                ppb->pb_nleft -= i;
        !            77:                dp += i;
        !            78:                len -= i;
        !            79:                rct += i;
        !            80:        }
        !            81: 
        !            82: # ifdef xCTR2
        !            83:        if (tTf(18, 1))
        !            84:                printf("%d\n", rct);
        !            85: # endif
        !            86:        return (rct);
        !            87: }

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