xilinx: Add models for LUTRAM cells. (#1537)

[yosys.git] / README.md

diff --git a/README.md b/README.md
index fdd4bb410d54f59f30016c0d990a459f27112b74..1ce5d47ea6510fa9d7c41f1dfbeaa26f3fa2fd33 100644 (file)
--- a/README.md
+++ b/README.md
@@ -343,6 +343,13 @@ Verilog Attributes and non-standard features
 - The ``clkbuf_sink`` attribute can be set on an input port of a module to
   request clock buffer insertion by the ``clkbufmap`` pass.
 
+- The ``clkbuf_inv`` attribute can be set on an output port of a module
+  with the value set to the name of an input port of that module.  When
+  the ``clkbufmap`` would otherwise insert a clock buffer on this output,
+  it will instead try inserting the clock buffer on the input port (this
+  is used to implement clock inverter cells that clock buffer insertion
+  will "see through").
+
 - The ``clkbuf_inhibit`` is the default attribute to set on a wire to prevent
   automatic clock buffer insertion by ``clkbufmap``. This behaviour can be
   overridden by providing a custom selection to ``clkbufmap``.
@@ -371,6 +378,11 @@ Verilog Attributes and non-standard features
   for example, to specify the clk-to-Q delay of a flip-flop for consideration
   during techmapping.
 
+- The frontend sets attributes ``always_comb``, ``always_latch`` and
+  ``always_ff`` on processes derived from SystemVerilog style always blocks
+  according to the type of the always. These are checked for correctness in
+  ``proc_dlatch``.
+
 - 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
@@ -510,6 +522,8 @@ from SystemVerilog:
   into a design with ``read_verilog``, all its packages are available to
   SystemVerilog files being read into the same design afterwards.
 
+- typedefs are supported (including inside packages)
+
 - SystemVerilog interfaces (SVIs) are supported. Modports for specifying whether
   ports are inputs or outputs are supported.