Searching for start and stop codons for protein sequencing of contigs
If your string is 'GGTAGCCAATTATGAACGAATAGGAC' then I would assume that you could separate this into coding and non-coding regions such as:
GG*TAG*CCAATT*    (non-coding)
ATG*AACGAA*TAG    (coding region)
*GAC              (non-coding)

It starts with a start codon ATG and ends with an end codon TAG.
Your first event position 12 does not make sense to me. What does * mean? It seems of that your sequence starts with GG which is not a triplet? Perhaps did you mean GGG?
I'm the author of node based DNA visualisation AminoSee. It has a bug in that it only renders half right: because DNA can be read backwards, and my program only does it forwards. I actually came to BioInformatics today to try and get my head around reading backwards and how that might work.
AminoSee only transcodes 3 base pairs at a time, and discards triplets that aren't, well, 3 base pairs longs. I'm self taught and so I guess unaware if it's possible to have any sequence that is not a multiple of 3. Perhaps it's possible. I assumed not. My program is more of an art piece that a science tool, but I plan to use it one day to perform a &quot;visual diff&quot; between two species (Humans and Chimp). See AminoSee  DNA Visualisation over at aminosee.funk.nz