sh(1) based snprintf-approach battle

NOTES:
The INPUT and OUTPUT values are in characters. The objective here is to, as
quickly as possible, trim a string to be no more N characters long. Here we pit
two competing approaches against each other, both using sh(1). One approach
uses a fork to awk(1) to trim the string to length. The competing approach
doesn't use any forks, but instead a novel algorithm based on sh(1) built-ins.

The awk(1) used is BSD's one-true-awk and the sh(1) used is FreeBSD's /bin/sh.
All the awk(1) is doing is basically a substr() of the input (multine allowed).
The competing sh(1)-only approach designed to defeat a fork to awk(1) uses a
dual-approach of calculating least-work to get to the answer and choosing the
best approach for each round (as multiple rounds are required to achieve the
desired result) based on built-in capabilities of FreeBSD's sh(1).

Let the battle begin:

LOOP-RUNS       INPUT   OUTPUT  AWK-TIME        SH-TIME         WINNER
1               10      6       0.017s          0.012s          SH
10              10      6       0.055s          0.014s          SH
100             10      6       0.436s          0.030s          SH
1000            10      6       4.518s          0.187s          SH
10000           10      6       45.299s         1.829s          SH
1               1035    6       0.022s          0.020s          SH
10              1035    6       0.061s          0.021s          SH
100             1035    6       0.462s          0.041s          SH
1000            1035    6       4.518s          0.233s          SH
10000           1035    6       50.581s         2.129s          SH
1               10251   6       0.024s          0.020s          SH
10              10251   6       0.072s          0.027s          SH
100             10251   6       0.509s          0.085s          SH
1000            10251   6       4.902s          0.744s          SH
10000           10251   6       50.073s         7.461s          SH
1               10      4       0.016s          0.012s          SH
10              10      4       0.056s          0.014s          SH
100             10      4       0.469s          0.028s          SH
1000            10      4       4.722s          0.168s          SH
10000           10      4       49.260s         1.588s          SH
1               1035    1029    0.023s          0.020s          SH
10              1035    1029    0.065s          0.022s          SH
100             1035    1029    0.490s          0.038s          SH
1000            1035    1029    5.002s          0.223s          SH
10000           1035    1029    51.070s         1.954s          SH
1               10251   10245   0.025s          0.021s          SH
10              10251   10245   0.069s          0.025s          SH
100             10251   10245   0.511s          0.082s          SH
1000            10251   10245   5.382s          0.583s          SH
10000           10251   10245   56.065s         5.817s          SH