Add a ROT13 workshop example #273
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FYI - @tcal-x |
| class FomuROT13Out(Module, AutoCSR): | ||
| def __init__(self, rot13_in): | ||
| self.csr = CSRStorage(8) | ||
| self.sync += If( # A-M, a-m |
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I think this could do with some more explanation :-)
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Added comments in 5a3c933, let me know if that's what you're looking for.
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Yeap starting to look good! I do think you might want a comment which says "we only rotate the alphabetic characters" (what about the numbers? :-) and maybe a link to the ROT13 wikipedia page?
Could be good to add a test bench in the future too....
From https://en.wikipedia.org/wiki/ROT13 it looks like memfrob() in the GNU C library could be an excellent target for this type of acceleration :-P
The GNU C library, a set of standard routines available for use in computer programming, contains a function—memfrob()[15]—which has a similar purpose to ROT13, although it is intended for use with arbitrary binary data. The function operates by combining each byte with the binary pattern 00101010 (42) using the exclusive or (XOR) operation.
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Linked the wiki page, added a brief explanation of the overall cipher, mentioned that it's limited to the English alphabet.
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Next step is to do that with a FIFO on each end :-) |
If you think I should, I'm happy to explore that and submit a PR for that instead. This was just me exploring wiring up signals, and (so far) CSRs are all I've learned! |
This is similar to the RGB litex/workshop example, but wires two CSRs together for a slightly more complicated example.
Poke a byte value into the "input" CSR via wishbone-tool, and retrieve the ROT13-encoded output byte from the "output" CSR.