Avalon stream update #666
Avalon stream update #666
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| @@ -123,6 +129,29 @@ package body avalon_stream_pkg is | |||
| return source.p_data_length; | |||
| end; | |||
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| function calc_empty_length(data_width : positive) return natural is | |||
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Overall, the PR looks good. However, I'm in doubt with this function. Isn't this equivalent to log2? Otherwise, should it be placed in a different location, to be reused by other parts of VUnit?
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Yes it is equivalent. However as I remember I had unexpected results due to rounding issues when used log2 and ceil/floor from ieee math library. I might applied them in wrong order or made other mistake, so will be grateful for some example.
Placing function for calculating vector width on in vunit lib is good idea overall. Its often used in test benches.
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Actually, I faced those issues myself too... I "fixed" them for n-1 or for 0, but I always have issues with some of them. Apart from that, I've seen variants of your function multiple times, but I cannot remember if it exists in VUnit's codebase already.
Let me ask @Paebbels, what is his suggested approach: do you use log2 + ceil/floor or a custom function? is there anything in the latest IEEE libs?
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The PoC Library provides:
log2ceil- 2s logarithm that rounds uplog2ceilnz- 2s logarithm that rounds up and is not zero (nz)
The latter function is sometimes called to_bits.
There is no standard implementation in IEEE libs. This could be implemented in CoreLib.
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Thanks @Paebbels!
@slaweksiluk, I'm thinking that we might move calc_empty_length to a new package in the core vunit/vunit/vhdl/core/src/utils_pkg.vhd. If your implementation is equivalent to either log2ceil or log2ceilnz from PoC, I think we should go with that (not adding PoC as a ref, but using the same name).
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There is also a similar function here. I'm for a "utility package" but I would avoid using that word since that is used to denote the set of optional VUnit packages, i.e. the packages that helps you write testbenches but aren't essential for running VUnit.
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@LarsAsplund what about vunit/vunit/vhdl/helpers/src/helpers_pkg.vhd?
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How to tell vunit to compile this new package? 215c64d
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@LarsAsplund is it ok to merge this before #520? |
Save captured data in queue to permit Avalon-St ready signal driving before user calls pop* function from main test bench.
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please review. Mind the commit f14fcae where I modified ready signal stimulation - to be truly random and not dependent on calling VC API functions in user main tb. |
also deleted gtkw files