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https://github.com/YosysHQ/yosys
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081d9318bc
This commit tries to carefully follow the documented behavior of LSE
and Synplify. It will use `syn_ramstyle` attribute if there are any
write ports, and `syn_romstyle` attribute otherwise.
* LSE supports both `syn_ramstyle` and `syn_romstyle`.
* Synplify only supports `syn_ramstyle`, with same values as LSE.
* Synplify also supports `syn_rw_conflict_logic`, which is not
documented as supported for LSE.
Limitations of the Yosys implementation:
* LSE/Synplify support `syn_ramstyle="block_ram,no_rw_check"`
syntax to turn off insertion of transparency logic. There is
currently no way to support multiple valued attributes in
memory_bram. It is also not clear if that is a good idea, since
it can cause sim/synth mismatches.
* LSE/Synplify/1364.1 support block ROM inference from full case
statements. Yosys does not currently perform this transformation.
* LSE/Synplify propagate `syn_ramstyle`/`syn_romstyle` attributes
from the module to the inner memories. There is currently no way
to do this in Yosys (attrmvcp only works on cells and wires).
27 lines
552 B
Plaintext
27 lines
552 B
Plaintext
bram $__TRELLIS_DPR16X4
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init 1
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abits 4
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dbits 4
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groups 2
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ports 1 1
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wrmode 0 1
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enable 0 1
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transp 0 0
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clocks 0 1
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clkpol 0 2
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endbram
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# The syn_* attributes are described in:
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# https://www.latticesemi.com/-/media/LatticeSemi/Documents/Tutorials/AK/LatticeDiamondTutorial311.ashx
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attr_icase 1
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match $__TRELLIS_DPR16X4
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attribute !syn_ramstyle syn_ramstyle=auto syn_ramstyle=distributed
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attribute !syn_romstyle syn_romstyle=auto
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attribute !ram_block
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attribute !rom_block
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attribute !logic_block
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make_outreg
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min wports 1
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endmatch
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