| Rev |
Log message |
Author |
Age |
Path |
| 19 |
Added the capability to accumulate bits internal to the FFT, only to drop
those extra bits just before the end. This helps to reduce truncation
error, and may even drop it by a factor of four (my own measurements). |
dgisselq |
3541d 12h |
/dblclockfft/trunk/sw/ |
| 16 |
Cleaned up the test bench build scripts, made sure license statements were
placed on all files, etc. |
dgisselq |
3543d 04h |
/dblclockfft/trunk/sw/ |
| 15 |
Added rounding into the routine to remove bias. All of the test benches have
been modified so that the FFT, with rounding, now passes. While the rounding
implementation applied does remove bias, it does not yet remove all bias.
Some work still remains. |
dgisselq |
3544d 03h |
/dblclockfft/trunk/sw/ |
| 14 |
Found several bugs in the previous version. The biggest were in the qtrstage.
Apparently, the qtrstage didn't work before, even though I thought it did.
Further, the FFT testbench has been adjusted to place proper values into
the fft_tb.dbl file it creates. (I've been testing it by reading this into
Octave, and visually inspecting the results--quantitative testing of the
fft_tb and ifft_tb are still lacking.) Now, however, if I cascade the
forward and reverse together, I seem to get something at least close to the
right answer. Close, of course, is relative. I think all that I still
struggle with is rounding and truncation errors, hence I'm checking in
my changes.
The FFT generator was also modified to allow arbitrary length paths
in the command line specified path prefix. This has not been tested.
A bug was also found in the butterfly, whereby for certain multiply delays
the butterfly would be unable to determine whether or not its results were
valid. Adding an extra bit to the FIFO address in these cases fixed the
problem. This change was encapsulated into the lgdelay() function, and
an additional bflydelay function. In my frustration, I modified the
fftstage function so that, when it is built, the parameters it is built
with are the default parameters. This should only affect testing, by
making any testing more realistic, but that may still remain to be seen.
Another change was made to the core generator, so that now when a core
is generated, the main file now contains a copy of the arguments that were
used when the core generator was invoked. This is good for posterity, in
case you ever need to ask yourself how I ended up here. |
dgisselq |
3545d 02h |
/dblclockfft/trunk/sw/ |
| 9 |
Now working on the test bench for the FFT. Currently, the FFT passes
all test bench "tests." However, the test bench does not yet accurately
report on the success of its work. This remains for future work. Lots
of bugs fixed while making this test bench code work.
(I should mention, while all test benches currently pass, that doesn't
mean that the code works ... yet. I just haven't found the bug that
breaks it.) |
dgisselq |
3551d 07h |
/dblclockfft/trunk/sw/ |
| 8 |
This completes the initial work on a test bench for the FFT stage. I
chose to test the odd 2048 stage only, but (hopefully) the testbench
will still apply to all other stages as well. At any rate, based upon
some trial runs, it looks like the FFT may be starting to work as well.
More testing is needed, for certain, but to do that I'm going to have
to figure out just what tests are needed, and how exactly to apply those
tests within the test bench construct. |
dgisselq |
3551d 14h |
/dblclockfft/trunk/sw/ |
| 6 |
Lots of work accomplished today. Test benches now exist and work for the:
butterfly, multiply, bitreversal, pairwise FFT stage (dblstage), and the
four-wise FFT stage (qtrstage). Work continues on the single (generic)
FFT stage, and (of course) the FFT isn't ready yet. A second commit will
follow this one shortly with the new files added (oops!--I should've added
them this time--my bad.) |
dgisselq |
3552d 01h |
/dblclockfft/trunk/sw/ |
| 5 |
The butterfly_tb is now written, and the butterfly succeeds at the test
bench! |
dgisselq |
3552d 08h |
/dblclockfft/trunk/sw/ |
| 3 |
The first upload of the s/w didn't take. Had it taken, the comment would've
been: This is the first upload of the double clocked FFT software. While it
should (roughly) be complete, a lot of work remains to be done--primarily
in building test benches, modifying the interface of fftgen to make it
more friendly, etc. In fact, the c++ code not only compiles, but the
Verilog code it produces actually builds as well!
Now, however, I have several test benches written, and have verified the
unit functionality of the multiply, bit reversal stage, the dblstage (FFT
len 2), and the qtrstage (FFT len 4). I then took a closer look at the
multiply, discovered it failed at signed integers and rebuilt it. The
new test bench tests the full 16-bit signed integer support properly. This
leaves butterflies and generic FFT stages that still need test benches, as
does the main (I)FFT program. |
dgisselq |
3552d 13h |
/dblclockfft/trunk/sw/ |
| 2 |
Here's an attempt at a first subversion update. |
dgisselq |
3552d 14h |
/dblclockfft/trunk/sw/ |
