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Annotation of 42BSD/ingres/source/ctlmod/pb_get.c, revision 1.1.1.1

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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