docs: add changelog.

docs/changes.rst

@@ -0,0 +1,103 @@
+Changelog
+#########
+
+This document describes changes to the public interfaces in the Amaranth language and standard library. It does not include most bug fixes or implementation changes.
+
+
+Version 0.3
+============
+
+The project has been renamed from nMigen to Amaranth.
+
+Features deprecated in version 0.2 have been removed.
+
+
+Migrating from version 0.2
+--------------------------
+
+.. currentmodule:: amaranth
+
+Apply the following changes to code written against nMigen 0.2 to migrate it to Amaranth 0.3:
+
+* Update ``import nmigen as nm`` :ref:`explicit prelude imports <lang-prelude>` to be ``import amaranth as am``, and adjust the code to use the ``am.*`` namespace.
+* Update ``import nmigen.*`` imports to be ``import amaranth.*``.
+* Update ``import nmigen_boards.*`` imports to be ``import amaranth_boards.*``.
+* Update board definitions using :class:`vendor.lattice_machxo2.LatticeMachXO2Platform` to use :class:`vendor.lattice_machxo_2_3l.LatticeMachXO2Platform`.
+* Update board definitions using :class:`vendor.xilinx_spartan_3_6.XilinxSpartan3APlatform`, :class:`vendor.xilinx_spartan_3_6.XilinxSpartan6Platform`, :class:`vendor.xilinx_7series.Xilinx7SeriesPlatform`, :class:`vendor.xilinx_ultrascale.XilinxUltrascalePlatform` to use :class:`vendor.xilinx.XilinxPlatform`.
+* Switch uses of :class:`hdl.ast.UserValue` to :class:`ValueCastable`; note that :class:`ValueCastable` does not inherit from :class:`Value`, and inheriting from :class:`Value` is not supported.
+* Remove uses of :class:`test.utils.FHDLTestCase` and vendor the implementation of :class:`test.utils.FHDLTestCase.assertFormal` if necessary.
+* Add an explicit ``ports=`` argument to uses of :func:`back.rtlil.convert` and :func:`back.verilog.convert` if missing.
+
+While code that uses the features listed as deprecated below will work in Amaranth 0.3, they will be removed in the next version.
+
+
+Language changes
+----------------
+
+.. currentmodule:: amaranth.hdl
+
+* Added: :class:`Value` can be used with :func:`abs`.
+* Added: :meth:`Value.rotate_left` and :meth:`Value.rotate_right`.
+* Added: :meth:`Value.shift_left` and :meth:`Value.shift_right`.
+* Added: :class:`ValueCastable`.
+* Deprecated: :class:`ast.UserValue`; use :class:`ValueCastable` instead.
+* Added: Divison and modulo operators can be used with a negative divisor.
+
+
+Standard library changes
+------------------------
+
+.. currentmodule:: amaranth.lib
+
+* Added: :class:`cdc.PulseSynchronizer`.
+* Added: :class:`cdc.AsyncFFSynchronizer`.
+* Changed: :class:`fifo.AsyncFIFO` is reset when the write domain is reset.
+* Added: :attr:`fifo.AsyncFIFO.r_rst` is asserted when the write domain is reset.
+* Added: :attr:`fifo.FIFOInterface.r_level` and :attr:`fifo.FIFOInterface.w_level`.
+
+
+Toolchain changes
+-----------------
+
+.. currentmodule:: amaranth
+
+* Changed: Backend and simulator reject wires larger than 65536 bits.
+* Added: Backend emits Yosys enumeration attributes for :ref:`enumeration-shaped <lang-shapeenum>` signals.
+* Added: If a compatible Yosys version is not installed, :mod:`back.verilog` will fall back to the `amaranth-yosys <https://github.com/amaranth-lang/amaranth-yosys>`_ PyPI package. The package can be :ref:`installed <install>` as ``amaranth[builtin-yosys]`` to ensure this dependency is available.
+* Added: :mod:`back.cxxrtl`.
+* Removed: The ``with Simulator(fragment, ...) as sim:`` form.
+* Removed: :meth:`sim.Simulator.add_process` with a generator argument.
+* Added: :meth:`build.BuildPlan.execute_remote_ssh`.
+* Deprecated: :class:`test.utils.FHDLTestCase`, with no replacement.
+* Deprecated: :func:`back.rtlil.convert()` and :func:`back.verilog.convert()` without an explicit `ports=` argument.
+
+
+Platform integration changes
+----------------------------
+
+.. currentmodule:: amaranth.vendor
+
+* Added: ``SB_LFOSC`` and ``SB_HFOSC`` as ``default_clk`` clock sources in :class:`lattice_ice40.LatticeICE40Platform`, .
+* Added: :class:`lattice_machxo2.LatticeMachXO2Platform` generates binary (``.bit``) bitstreams.
+* Added: :class:`lattice_machxo_2_3l.LatticeMachXO3LPlatform`.
+* Deprecated: :mod:`lattice_machxo2`; use :class:`lattice_machxo_2_3l.LatticeMachXO2Platform` instead.
+* Removed: :class:`xilinx_7series.Xilinx7SeriesPlatform.grade`; this family has no temperature grades.
+* Removed: and :class:`xilinx_ultrascale.XilinxUltrascalePlatform.grade`; this family has temperature grade as part of speed grade.
+* Added: Symbiflow toolchain support for :class:`xilinx_7series.Xilinx7SeriesPlatform`.
+* Added: :class:`lattice_machxo_2_3l.LatticeMachXO2Or3LPlatform` generates separate Flash and SRAM SVF programming vectors, ``{{name}}_flash.svf`` and ``{{name}}_sram.svf``.
+* Deprecated: :class:`lattice_machxo_2_3l.LatticeMachXO2Or3LPlatform` SVF programming vector ``{{name}}.svf``; use ``{{name}}_flash.svf`` instead.
+* Added: :class:`quicklogic.QuicklogicPlatform`.
+* Added: ``cyclonev_oscillator`` as ``default_clk`` clock source in :class:`intel.IntelPlatform`.
+* Added: ``add_settings`` and ``add_constraints`` overrides in :class:`intel.IntelPlatform`.
+* Added: :class:`xilinx.XilinxPlatform`.
+* Deprecated: :class:`xilinx_spartan_3_6.XilinxSpartan3APlatform`, :class:`xilinx_spartan_3_6.XilinxSpartan6Platform`, :class:`xilinx_7series.Xilinx7SeriesPlatform`, :class:`xilinx_ultrascale.XilinxUltrascalePlatform`; use :class:`xilinx.XilinxPlatform` instead.
+* Added: Mistral toolchain support for :class:`intel.IntelPlatform`.
+* Added: ``synth_design_opts`` override in :class:`xilinx.XilinxPlatform`.
+
+
+Versions 0.1, 0.2
+=================
+
+No changelog is provided for these versions.
+
+The PyPI packages were published under the ``nmigen`` namespace, rather than ``amaranth``.

docs/index.rst

@@ -15,3 +15,4 @@ Language & toolchain
    lang
    stdlib
    platform
+   changes

docs/lang.rst

@@ -126,6 +126,8 @@ Shapes can be *cast* from other objects, which are called *shape-castable*. Cast
 Casting to a shape can be done explicitly with ``Shape.cast``, but is usually implicit, since shape-castable objects are accepted anywhere shapes are.
 
 
+.. _lang-shapeint:
+
 Shapes from integers
 --------------------
 
@@ -139,6 +141,8 @@ Casting a shape from an integer ``i`` is a shorthand for constructing a shape wi
    unsigned(3)
 
 
+.. _lang-shaperange:
+
 Shapes from ranges
 ------------------
 
@@ -174,6 +178,8 @@ Specifying a shape with a range is convenient for counters, indexes, and all oth
    Be mindful of this edge case!
 
 
+.. _lang-shapeenum:
+
 Shapes from enumerations
 ------------------------