String message parse optimization - the game

[Łukasz]

Your task is whipping up a piece of code that can unravel a string stuffed with uint64 data, all dressed up in that fancy communication protocol jacket. But hold your horses, partner! The catch is to make it faster than my own fancy footwork. Giddy up and get coding! 

Example of slow solution: 

Much faster solution:

 

Y'all can lay your eyes on the testin' stuff right down yonder in that there attachment. And guess what? There's a little description of that frame thingamajig to tickle your fancy. So put on your explorin' hat and give it a gander!

decode-frame.vi

Edited August 29, 2023 by Łukasz

[cordm]

Is the frame size 16 bytes? In the first you use 14, in the second 16.

This is slightly faster:

The biggest hurdle is converting the endianness, I do not think you can get much faster with conversion.

I tried to be clever using BLAS dcopy for copying out the relevant part, but the conversion kills the performance gain.

decode-frame-cm.vi

[Łukasz]

oh true, the frame is 16 bytes long. So your solution is the fastest now. 

[LogMAN]

2 hours ago, cordm said:

I tried to be clever using BLAS dcopy for copying out the relevant part, but the conversion kills the performance gain.

It is actually much faster on my machine. Here are a few results:

• @Łukasz
  • Fast solution: ~30 µs
• @cordm
  • Case 1 (really slow): ~403 µs
  • Case 2 (good performance and readability): ~54 µs -- output is wrong, see below.
  • Case 3 (): ~235 µs
  • Case 4 (original solution): ~30 µs
  • Case 5 (LV200000_BLASLAPACK.dll): ~14 µs
  • Case 6 (LVBLAS.dll:BLASCopyVectorH): ~16 µs

-- Windows 11, LabVIEW 2020 SP1 (32-bit)

2 hours ago, cordm said:

This is slightly faster:

This code actually truncates the last value because the length of the source array becomes odd.

Here are two possible fixes. The second one is slightly faster for me.

1) Append the final element: ~60 µs. (slightly slower than before)

2) Rotate the string before conversion: ~42 µs.

[Łukasz]

I tried all the solutions using LabVIEW 64-bit on Ubuntu. I fixed case 2, and cases 5 and 6 produced very similar results. I'm a bit worried about using BLAS VIs because they might cause problems during the building process.

@cordm and @LogMAN I truly want to express my gratitude for your help.