Embeded Sieve of Eratosthenes

I'm getting really weird performance from the Tiva C Launchpad when using the UART. The board itself is an ICDI programmer but it also serves as a serial terminal at /dev/ttyACM0. The problem I'm having seems to be with synchronization. Some of the characters will be dropped, but other times I get complete gibberish. At any rate, I have the firmware looping at after a minute or two everything is rock-steady, but the unstable performance returns once again after power-cycling.

I was developing this via SSH, with my production machine in the other room while I was on the sofa watching March Madness. I pulled out an FTDI breakout board; only needing to hook up one wire from TX on the Launchpad to RX on the FTDI (both are running from USB on the same machine which serves as the ground reference).

Has anyone else experience this serial performance issues before?

It took me a while to figure out how I wanted to do this, but I now have a functional template that works with TI's restrictive licensing on their example files.

https://github.com/szczys/tiva-c-launchpad-template

This open source template is a starting place for those interested in bare-metal programming Tiva chips using open source tools. It uses the libraries from the TivaWare package, as well as the example linker script and start code. Since neither of those files can be included in an open source repo, the Makefile creates symbolic links before compiling the package.

First off, TI I love your dev boards (and obviously your chips) but I hate your copyright statement on the top of all of the demo files in the TivaWare package. I can't put code up for this project yet because of this statement:

You may not combine this software with "viral" open-source software in order to form a larger program.

I'm working on my own Makefile to get around this nonsense.