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Annotation of 43BSDReno/usr.sbin/traceroute/median.awk, revision 1.1

1.1     ! root        1: #!/bin/awk -f
        !             2: #
        !             3: # Copyright (c) 1990 The Regents of the University of California.
        !             4: # All rights reserved.
        !             5: #
        !             6: # This code is derived from software contributed to Berkeley by
        !             7: # Van Jacobson.
        !             8: #
        !             9: # Redistribution and use in source and binary forms are permitted
        !            10: # provided that the above copyright notice and this paragraph are
        !            11: # duplicated in all such forms and that any documentation,
        !            12: # advertising materials, and other materials related to such
        !            13: # distribution and use acknowledge that the software was developed
        !            14: # by the University of California, Berkeley.  The name of the
        !            15: # University may not be used to endorse or promote products derived
        !            16: # from this software without specific prior written permission.
        !            17: # THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            18: # IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            19: # WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            20: #
        !            21: #      @(#)median.awk  5.2 (Berkeley) 4/28/90
        !            22: #
        !            23: /^ *[0-9]/     {
        !            24:        # print out the median time to each hop along a route.
        !            25:        tottime = 0; n = 0;
        !            26:        for (f = 5; f <= NF; ++f) {
        !            27:                if ($f == "ms") {
        !            28:                        ++n
        !            29:                        time[n] = $(f - 1)
        !            30:                }
        !            31:        }
        !            32:        if (n > 0) {
        !            33:                # insertion sort the times to find the median
        !            34:                for (i = 2; i <= n; ++i) {
        !            35:                        v = time[i]; j = i - 1;
        !            36:                        while (time[j] > v) {
        !            37:                                time[j+1] = time[j];
        !            38:                                j = j - 1;
        !            39:                                if (j < 0)
        !            40:                                        break;
        !            41:                        }
        !            42:                        time[j+1] = v;
        !            43:                }
        !            44:                if (n > 1 && (n % 2) == 0)
        !            45:                        median = (time[n/2] + time[(n/2) + 1]) / 2
        !            46:                else
        !            47:                        median = time[(n+1)/2]
        !            48: 
        !            49:                print $1, median
        !            50:        }
        !            51: }

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