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docs: document S&R undefined for $dffsr and $dffsre

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Emil J. Tywoniak 2026-03-04 19:39:41 +01:00
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8
docs/source/cell/gate_reg_ff.rst
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@ -154,6 +154,10 @@ to the following Verilog code template, where ``RST_EDGE`` is ``posedge`` if
``RST_LVL`` if ``1``, ``negedge`` otherwise, and ``SET_EDGE`` is ``posedge`` if
``SET_LVL`` if ``1``, ``negedge`` otherwise.
When both set and reset are active, the state and output is undefined. The Verilog
code model does not correspond to this due to limitations
of synthesizable Verilog.
.. code-block:: verilog
:force:
@ -187,6 +191,10 @@ types relate to the following Verilog code template, where ``RST_EDGE`` is
``posedge`` if ``RST_LVL`` if ``1``, ``negedge`` otherwise, and ``SET_EDGE`` is
``posedge`` if ``SET_LVL`` if ``1``, ``negedge`` otherwise.
When both set and reset are active, the state and output is undefined. The Verilog
code model does not correspond to this due to limitations
of synthesizable Verilog.
.. code-block:: verilog
:force:

1
docs/source/cell/word_reg.rst
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@ -78,6 +78,7 @@ D-type flip-flops with asynchronous set and reset are represented by `$dffsr`
cells. As the `$dff` cells they have ``CLK``, ``D`` and ``Q`` ports. In addition
they also have multi-bit ``SET`` and ``CLR`` input ports and the corresponding
polarity parameters, like `$sr` cells.
When both set and reset are active, the state and output is undefined.
D-type flip-flops with enable are represented by `$dffe`, `$adffe`, `$aldffe`,
`$dffsre`, `$sdffe`, and `$sdffce` cells, which are enhanced variants of `$dff`,