Weekly Report: Week 8

This was a short week as I had to go out of town for three days. I have mostly worked on floating point conversions and arithmetic modules this week.

Float 16 Arithmetic: link

  • The float 16 multiplier which I had already completed in migen, I ported it to litex to send out a pull request and get it reviewed. While porting I was getting a error while trying to run the testbench. I have added this pastebin link in the pull request comments as well. From my understanding, somewhere in the streamer something  is not defined as a Signal object. Which is causing this error. This was working fine in the migen environment, and I suppose there is some difference in implementation of streamer in litex.
  • Completed a five stage pipelined version of 16 bit floating point adder. This has been done under the migen environment of HDMI2USB-misoc-firmware. After some bug fixing, this has been tested to be working in the migen simulation environment.  Also ported this to litex for sending out the pull request and getting it reviewed. I encounter the similar error, which I encountered while porting the float mult module.
  • I sent the pull request later in the week, made the required changes as mentioned in the comments. This was mostly correct variable names and adding module level and class docstrings.

Float 16 Color Space Conversion: link

  • I had already sent out a pull request for this last week, but since I was focussing on other this laster last week, couldn’t look at the pull request comments.  Among many things I added a generic submodule for leading one detector. Earlier this was done using a number of if else conditions, and now done using a simple for loop, though I feel that this has made the simulation slower. Fixed some variable names and added more for loops to clean up the code.
  • From the the discussions I had with mithro and _florent_, it was suggested that it might be good to explore this implementation using a lookup table. At least for the int8 to float16 conversion, as the size will be only 256*16bits. I added the contents of lookup table using the already defined int8 to float16 test model functions I wrote for testing. Can do a similar thing for the reverse conversion, but the size of lookup table (65536*8bits) might be too big to be better than the earlier implementation.

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