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Diffstat (limited to 'README')
| -rw-r--r-- | README | 7 |
1 files changed, 6 insertions, 1 deletions
@@ -232,7 +232,8 @@ Verilog Attributes and non-standard features - The "nolatches" attribute on modules or always-blocks prohibits the generation of logic-loops for latches. Instead - all not explicitly assigned values default to x-bits. + all not explicitly assigned values default to x-bits. This does + not affect clocked storage elements such as flip-flops. - The "nosync" attribute on registers prohibits the generation of a storage element. The register itself will always have all bits set @@ -246,6 +247,10 @@ Verilog Attributes and non-standard features passes to identify input and output ports of cells. The verilog backend also does not output placeholder modules on default. +- The "keep" attribute on cells is used to mark cells that should never be + removed by the optimizer. This is used for example for cells that have + hidden connections that are not part of the netlist, such as IO pads. + - In addition to the (* ... *) attribute syntax, yosys supports the non-standard {* ... *} attribute syntax to set default attributes for everything that comes after the {* ... *} statement. (Reset |