Hub test case proposal
Tubular
Posts: 4,622
I've come up with this as a possible test case for discussion / cycle profiling. It's based on acquiring live data from a camera (eg PropCam!) that is only known at runtime, and passing the data through an arbitrary transfer function (eg to do histogram equalization) that is located in the hub memory
I've deliberately limited it to 4 bit input data as I think that's sufficient to see whether claims hold true, when manipulating the input data for edge cases
There may be up to 32 cycles of timing variability depending on where things start and end relative to the cog's natural hub slot. However there are three opportunities to 'slip' in between hub reads, which could mean 45 cycles that would exceed the 32 cycle timing allowance and indicate an 'issue'. If necessary we could examine a RdBloc version
I've deliberately limited it to 4 bit input data as I think that's sufficient to see whether claims hold true, when manipulating the input data for edge cases
There may be up to 32 cycles of timing variability depending on where things start and end relative to the cog's natural hub slot. However there are three opportunities to 'slip' in between hub reads, which could mean 45 cycles that would exceed the 32 cycle timing allowance and indicate an 'issue'. If necessary we could examine a RdBloc version
'Test case: acquiring and displaying data from Propcam. Input: 4 bit pixels, 'values could be anything 0..F eg all black 0,0,0,0, or a gradient 0,1,2,3 or 6,4,2,0 etc 'Runs through a nonlinear transform for equalization or other transform 'hub mem < $1ff. Cog memory lookup value starts at hub base = $2000 ($2000..$200F) 'acquire data mov $100, pixelvalue0 'acquire 4 bit pixel values from camera mov $101, pixelvalue1 'could be any value 0..$F mov $102, pixelvalue2 mov $103, pixelvalue3 'turn it into lookup pointers add pixelvalue0, hubbase 'add 2000 to convert to hub ram pointer for lookup. via constant eg hubbase=$2000 add pixelvalue1, hubbase add pixelvalue2, hubbase add pixelvalue3, hubbase 'so far this is all in cog and deterministic and file 'look up the transformed data to display mov ticks1, CNT rdlong displayvalue0, pixelvalue0 'determine transformed value to display for first pixel rdlong displayvalue1, pixelvalue1 rdlong displayvalue2, pixelvalue2 rdlong displayvalue3, pixelvalue3 mov ticks2, CNT 'display the transformed data...