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| <section id="in-f4pga"> | |
| <h1 id="flows-f4pga--page-root">In F4PGA<a class="headerlink" href="#flows-f4pga--page-root" title="Link to this heading">¶</a></h1> | |
| <section id="synthesis"> | |
| <h2 id="synthesis">Synthesis<a class="headerlink" href="#synthesis" title="Link to this heading">¶</a></h2> | |
| <p>In the F4PGA toolchain synthesis is made with the use of Yosys, that is able to perform all the mentioned steps and | |
| convert HDL to netlist description. | |
| The result of these steps is written to a file in <code class="docutils literal notranslate"><span class="pre">.eblif</span></code> format.</p> | |
| <section id="yosys"> | |
| <span id="flows-f4pga-yosys"></span><h3 id="yosys">Yosys<a class="headerlink" href="#yosys" title="Link to this heading">¶</a></h3> | |
| <p>Yosys is a Free and Open Source Verilog HDL synthesis tool. | |
| It was designed to be highly extensible and multiplatform. | |
| In F4PGA toolchain, it is responsible for the whole synthesis process described in <a class="reference external" href="./design-flow.html">FPGA Design Flow</a></p> | |
| <p>It is not necessary to call Yosys directly using F4PGA. | |
| Nevertheless, the following description, should provide sufficient introduction to Yosys usage inside the project. | |
| It is also a good starting point for a deeper understanding of the whole toolchain.</p> | |
| <section id="short-description"> | |
| <h4 id="short-description">Short description<a class="headerlink" href="#short-description" title="Link to this heading">¶</a></h4> | |
| <p>Yosys consists of several subsystems. Most distinguishable are the first and last ones used in the synthesis process, | |
| called <em>frontend</em> and <em>backend</em> respectively. | |
| Intermediate subsystems are called <em>passes</em>.</p> | |
| <p>The <em>frontend</em> is responsible for changing the Verilog input file into an internal Yosys, representation which is common | |
| for all <em>passes</em> used by the program. | |
| The <em>passes</em> are responsible for a variety of optimizations (<code class="docutils literal notranslate"><span class="pre">opt_</span></code>) and simplifications (<code class="docutils literal notranslate"><span class="pre">proc_</span></code>).</p> | |
| <p>Two <em>passes</em>, that are worth to mention separately are <code class="docutils literal notranslate"><span class="pre">ABC</span></code> and <code class="docutils literal notranslate"><span class="pre">techmap</span></code>. | |
| The first one optimizes logic functions from the design and assigns obtained results into Look Up Tables (LUTs) of | |
| chosen width. | |
| The second mentioned <em>pass</em> - <code class="docutils literal notranslate"><span class="pre">techmap</span></code> is responsible for mapping the synthesized design from Yosys internal blocks | |
| to the primitives used by the implementation tool. | |
| Recommended synthesis flows for different FPGAs are combined into macros i.e. <code class="docutils literal notranslate"><span class="pre">synth_ice40</span></code> (for Lattice iCE40 FPGA) | |
| or <code class="docutils literal notranslate"><span class="pre">synth_xilinx</span></code> (for Xilinx 7-series FPGAs).</p> | |
| <p>The <em>backend</em> on the other hand, is responsible for converting internal Yosys representation into one of the | |
| standardized formats. | |
| F4PGA uses <code class="docutils literal notranslate"><span class="pre">.eblif</span></code> as its output file format.</p> | |
| </section> | |
| <section id="usage-in-toolchain"> | |
| <h4 id="usage-in-toolchain">Usage in Toolchain<a class="headerlink" href="#usage-in-toolchain" title="Link to this heading">¶</a></h4> | |
| <p>All operations performed by Yosys are written in <code class="docutils literal notranslate"><span class="pre">.tcl</span></code> script. Commands used | |
| in the scripts are responsible for preparing output file to match with the | |
| expectations of other toolchain tools. | |
| There is no need to change it even for big designs. | |
| An example configuration script can be found below:</p> | |
| <div class="highlight-tcl notranslate"><div class="highlight"><pre><span></span><span class="nv">yosys</span><span class="w"> </span><span class="o">-</span>import | |
| <span class="nv">synth_ice40</span><span class="w"> </span><span class="o">-</span>nocarry | |
| <span class="nv">opt_expr</span><span class="w"> </span><span class="o">-</span>undriven | |
| <span class="nv">opt_clean</span> | |
| <span class="nv">setundef</span><span class="w"> </span><span class="o">-</span>zero<span class="w"> </span><span class="o">-</span>params | |
| <span class="nv">write_blif</span><span class="w"> </span><span class="o">-</span>attr<span class="w"> </span><span class="o">-</span>cname<span class="w"> </span><span class="o">-</span>param<span class="w"> </span><span class="nv">$::env</span><span class="k">(</span><span class="nv">OUT_EBLIF</span><span class="k">)</span> | |
| <span class="nv">write_verilog</span><span class="w"> </span><span class="nv">$::env</span><span class="k">(</span><span class="nv">OUT_SYNTH_V</span><span class="k">)</span> | |
| </pre></div> | |
| </div> | |
| <p>It can be seen that this script performs a platform-specific process of synthesis, some optimization steps (<code class="docutils literal notranslate"><span class="pre">opt_</span></code> | |
| commands), and writes the final file in <code class="docutils literal notranslate"><span class="pre">.eblif</span></code> and Verilog formats. | |
| Yosys synthesis configuration scripts are platform-specific and can by found in <code class="docutils literal notranslate"><span class="pre"><platform-dir>/yosys/synth.tcl</span></code> in | |
| the <a class="extlink-gh reference external" href="https://github.com/SymbiFlow/f4pga-arch-defs">F4PGA Architecture Definitions</a> repository.</p> | |
| <p>To understand performed operations, view the log file. | |
| It is usually generated in the project build directory. It should be named <code class="docutils literal notranslate"><span class="pre">top.eblif.log</span></code>.</p> | |
| </section> | |
| <section id="output-analysis"> | |
| <h4 id="output-analysis">Output analysis<a class="headerlink" href="#output-analysis" title="Link to this heading">¶</a></h4> | |
| <p>Input file:</p> | |
| <div class="highlight-verilog notranslate"><div class="highlight"><pre><span></span><span class="k">module</span><span class="w"> </span><span class="n">top</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="k">input</span><span class="w"> </span><span class="n">clk</span><span class="p">,</span> | |
| <span class="w"> </span><span class="k">output</span><span class="w"> </span><span class="n">LD7</span><span class="p">,</span> | |
| <span class="p">);</span> | |
| <span class="w"> </span><span class="k">localparam</span><span class="w"> </span><span class="n">BITS</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">1</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">localparam</span><span class="w"> </span><span class="n">LOG2DELAY</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">25</span><span class="p">;</span> | |
| <span class="w"> </span><span class="kt">reg</span><span class="w"> </span><span class="p">[</span><span class="n">BITS</span><span class="o">+</span><span class="n">LOG2DELAY</span><span class="o">-</span><span class="mh">1</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">counter</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">always</span><span class="w"> </span><span class="p">@(</span><span class="k">posedge</span><span class="w"> </span><span class="n">clk</span><span class="p">)</span><span class="w"> </span><span class="k">begin</span> | |
| <span class="w"> </span><span class="n">counter</span><span class="w"> </span><span class="o"><=</span><span class="w"> </span><span class="n">counter</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mh">1</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">end</span> | |
| <span class="w"> </span><span class="k">assign</span><span class="w"> </span><span class="p">{</span><span class="n">LD7</span><span class="p">}</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">counter</span><span class="w"> </span><span class="o">>></span><span class="w"> </span><span class="n">LOG2DELAY</span><span class="p">;</span> | |
| <span class="k">endmodule</span> | |
| </pre></div> | |
| </div> | |
| <p>after synthesis is described only with use of primitives appropriate for | |
| chosen platform:</p> | |
| <div class="highlight-verilog notranslate"><div class="highlight"><pre><span></span><span class="k">module</span><span class="w"> </span><span class="n">top</span><span class="p">(</span><span class="n">clk</span><span class="p">,</span><span class="w"> </span><span class="n">LD7</span><span class="p">);</span> | |
| <span class="w"> </span><span class="kt">wire</span><span class="w"> </span><span class="p">[</span><span class="mh">25</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">_000_</span><span class="p">;</span> | |
| <span class="w"> </span><span class="kt">wire</span><span class="w"> </span><span class="n">_001_</span><span class="p">;</span> | |
| <span class="p">...</span> | |
| <span class="w"> </span><span class="n">FDRE_ZINI</span><span class="w"> </span><span class="p">#(</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">IS_C_INVERTED</span><span class="p">(</span><span class="mh">1'h0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">ZINI</span><span class="p">(</span><span class="mh">1'h1</span><span class="p">)</span> | |
| <span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="n">_073_</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">C</span><span class="p">(</span><span class="n">clk</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">CE</span><span class="p">(</span><span class="n">_012_</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">D</span><span class="p">(</span><span class="n">_000_</span><span class="p">[</span><span class="mh">0</span><span class="p">]),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">Q</span><span class="p">(</span><span class="n">counter</span><span class="p">[</span><span class="mh">0</span><span class="p">]),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">R</span><span class="p">(</span><span class="n">_013_</span><span class="p">)</span> | |
| <span class="w"> </span><span class="p">);</span> | |
| <span class="p">...</span> | |
| <span class="w"> </span><span class="n">SR_GND</span><span class="w"> </span><span class="n">_150_</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">GND</span><span class="p">(</span><span class="n">_062_</span><span class="p">)</span> | |
| <span class="w"> </span><span class="p">);</span> | |
| <span class="w"> </span><span class="k">assign</span><span class="w"> </span><span class="n">_003_</span><span class="p">[</span><span class="mh">25</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">_000_</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">assign</span><span class="w"> </span><span class="n">counter</span><span class="p">[</span><span class="mh">25</span><span class="p">]</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">LD7</span><span class="p">;</span> | |
| <span class="k">endmodule</span> | |
| </pre></div> | |
| </div> | |
| <p>The same structure is described by the <code class="docutils literal notranslate"><span class="pre">.eblif</span></code> file.</p> | |
| </section> | |
| <section id="technology-mapping-in-f4pga-toolchain"> | |
| <h4 id="technology-mapping-in-f4pga-toolchain">Technology mapping in F4PGA toolchain<a class="headerlink" href="#technology-mapping-in-f4pga-toolchain" title="Link to this heading">¶</a></h4> | |
| <p>It is important to understand the connection between the synthesis and | |
| implementation tools used in the F4PGA toolchain. As mentioned before, | |
| synthesis tools like Yosys take the design description from the source files | |
| and convert them into a netlist that consists of the primitives used by | |
| the implementation tool. Usually, to support multiple implementation tools, | |
| an additional intermediate representation of FPGA primitives is provided. | |
| The process of translating the primitives from the synthesis | |
| tool’s internal representation to the specific primitives used in the | |
| implementation tools is called technology mapping (or techmapping).</p> | |
| </section> | |
| <section id="technology-mapping-for-vpr"> | |
| <h4 id="technology-mapping-for-vpr">Technology mapping for VPR<a class="headerlink" href="#technology-mapping-for-vpr" title="Link to this heading">¶</a></h4> | |
| <p>As mentioned before, VPR is one of the implementation tools (often referred to | |
| as Place & Route or P&R tools) used in F4PGA. By default, the F4PGA | |
| toolchain uses it during bitstream generation for, i.e., Xilinx 7-Series | |
| devices. Since the architecture models for this FPGA family were created from | |
| scratch, appropriate techmaps were needed to instruct Yosys on translating | |
| the primitives to the versions compatible with VPR.</p> | |
| <p>The clock buffers used in the 7-Series devices are a good example for explaining | |
| the techmapping process. Generally, as stated in the | |
| <a class="reference external" href="https://www.xilinx.com/support/documentation/user_guides/ug472_7Series_Clocking.pdf#page=38">Xilinx 7 Series FPGAs Clocking Resources User Guide</a>, a designer has various | |
| buffer types that they can use in designs:</p> | |
| <ul class="simple"> | |
| <li><p><code class="docutils literal notranslate"><span class="pre">BUFGCTRL</span></code></p></li> | |
| <li><p><code class="docutils literal notranslate"><span class="pre">BUFG</span></code></p></li> | |
| <li><p><code class="docutils literal notranslate"><span class="pre">BUFGCE</span></code></p></li> | |
| <li><p><code class="docutils literal notranslate"><span class="pre">BUFGCE_1</span></code></p></li> | |
| <li><p><code class="docutils literal notranslate"><span class="pre">BUFGMUX</span></code></p></li> | |
| <li><p><code class="docutils literal notranslate"><span class="pre">BUFGMUX_1</span></code></p></li> | |
| <li><p><code class="docutils literal notranslate"><span class="pre">BUFGMUX_CTRL</span></code></p></li> | |
| </ul> | |
| <p>Nevertheless, the actual chips consist only of the <code class="docutils literal notranslate"><span class="pre">BUFGCTRL</span></code> primitives, | |
| which are the most universal and can function as other clock buffer | |
| primitives from the Xilinx manual. Because of that, only one architecture model | |
| is required for VPR. The rest of the primitives are mapped to this general | |
| buffer during the techmapping process. The model of <code class="docutils literal notranslate"><span class="pre">BUFGCTRL</span></code> primitive used | |
| by VPR is called <code class="docutils literal notranslate"><span class="pre">BUFGCTR_VPR</span></code> (More information about the architecture | |
| modeling in VPR can be found in the <a class="reference external" href="https://docs.verilogtorouting.org/en/latest/arch/">VTR FPGA Architecture Description</a>).</p> | |
| <p>Support for particular primitive in VTR consist of two files:</p> | |
| <ul class="simple"> | |
| <li><p>Model XML (<code class="docutils literal notranslate"><span class="pre">xxx.model.xml</span></code>) - Contains general information about | |
| the module’s input and output ports and their relations.</p></li> | |
| <li><p>Physical Block XML (<code class="docutils literal notranslate"><span class="pre">xxx.pb_type.xml</span></code>) - Describes the actual layout of the | |
| primitive, with information about the timings, internal connections, etc.</p></li> | |
| </ul> | |
| <p>Below you can see the pb_type XML for <code class="docutils literal notranslate"><span class="pre">BUFGCTRL_VPR</span></code> primitive:</p> | |
| <div class="highlight-xml notranslate"><div class="highlight"><pre><span></span><span class="cm"><!-- Model of BUFG group in BUFG_CLK_TOP/BOT --></span> | |
| <span class="nt"><pb_type</span><span class="w"> </span><span class="na">name=</span><span class="s">"BLK-TL-BUFGCTRL"</span><span class="w"> </span><span class="na">xmlns:xi=</span><span class="s">"https://www.w3.org/2001/XInclude"</span><span class="nt">></span> | |
| <span class="w"> </span><span class="nt"><output</span><span class="w"> </span><span class="na">name=</span><span class="s">"O"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"CE0"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"CE1"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><clock</span><span class="w"> </span><span class="na">name=</span><span class="s">"I0"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><clock</span><span class="w"> </span><span class="na">name=</span><span class="s">"I1"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"IGNORE0"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"IGNORE1"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"S0"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"S1"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><mode</span><span class="w"> </span><span class="na">name=</span><span class="s">"EMPTY"</span><span class="nt">></span> | |
| <span class="w"> </span><span class="nt"><pb_type</span><span class="w"> </span><span class="na">name=</span><span class="s">"empty"</span><span class="w"> </span><span class="na">blif_model=</span><span class="s">".latch"</span><span class="w"> </span><span class="na">num_pb=</span><span class="s">"1"</span><span class="w"> </span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><interconnect</span><span class="w"> </span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"></mode></span> | |
| <span class="w"> </span><span class="nt"><mode</span><span class="w"> </span><span class="na">name=</span><span class="s">"BUFGCTRL"</span><span class="nt">></span> | |
| <span class="w"> </span><span class="nt"><pb_type</span><span class="w"> </span><span class="na">name=</span><span class="s">"BUFGCTRL_VPR"</span><span class="w"> </span><span class="na">blif_model=</span><span class="s">".subckt BUFGCTRL_VPR"</span><span class="w"> </span><span class="na">num_pb=</span><span class="s">"1"</span><span class="nt">></span> | |
| <span class="w"> </span><span class="nt"><output</span><span class="w"> </span><span class="na">name=</span><span class="s">"O"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"CE0"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"CE1"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><clock</span><span class="w"> </span><span class="na">name=</span><span class="s">"I0"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><clock</span><span class="w"> </span><span class="na">name=</span><span class="s">"I1"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"IGNORE0"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"IGNORE1"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"S0"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><input</span><span class="w"> </span><span class="na">name=</span><span class="s">"S1"</span><span class="w"> </span><span class="na">num_pins=</span><span class="s">"1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><metadata></span> | |
| <span class="w"> </span><span class="nt"><meta</span><span class="w"> </span><span class="na">name=</span><span class="s">"fasm_params"</span><span class="nt">></span> | |
| <span class="w"> </span>ZPRESELECT_I0<span class="w"> </span>=<span class="w"> </span>ZPRESELECT_I0 | |
| <span class="w"> </span>ZPRESELECT_I1<span class="w"> </span>=<span class="w"> </span>ZPRESELECT_I1 | |
| <span class="w"> </span>IS_IGNORE0_INVERTED<span class="w"> </span>=<span class="w"> </span>IS_IGNORE0_INVERTED | |
| <span class="w"> </span>IS_IGNORE1_INVERTED<span class="w"> </span>=<span class="w"> </span>IS_IGNORE1_INVERTED | |
| <span class="w"> </span>ZINV_CE0<span class="w"> </span>=<span class="w"> </span>ZINV_CE0 | |
| <span class="w"> </span>ZINV_CE1<span class="w"> </span>=<span class="w"> </span>ZINV_CE1 | |
| <span class="w"> </span>ZINV_S0<span class="w"> </span>=<span class="w"> </span>ZINV_S0 | |
| <span class="w"> </span>ZINV_S1<span class="w"> </span>=<span class="w"> </span>ZINV_S1 | |
| <span class="w"> </span><span class="nt"></meta></span> | |
| <span class="w"> </span><span class="nt"></metadata></span> | |
| <span class="w"> </span><span class="nt"></pb_type></span> | |
| <span class="w"> </span><span class="nt"><interconnect></span> | |
| <span class="w"> </span><span class="nt"><direct</span><span class="w"> </span><span class="na">name=</span><span class="s">"O"</span><span class="w"> </span><span class="na">input=</span><span class="s">"BUFGCTRL_VPR.O"</span><span class="w"> </span><span class="na">output=</span><span class="s">"BLK-TL-BUFGCTRL.O"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><direct</span><span class="w"> </span><span class="na">name=</span><span class="s">"CE0"</span><span class="w"> </span><span class="na">input=</span><span class="s">"BLK-TL-BUFGCTRL.CE0"</span><span class="w"> </span><span class="na">output=</span><span class="s">"BUFGCTRL_VPR.CE0"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><direct</span><span class="w"> </span><span class="na">name=</span><span class="s">"CE1"</span><span class="w"> </span><span class="na">input=</span><span class="s">"BLK-TL-BUFGCTRL.CE1"</span><span class="w"> </span><span class="na">output=</span><span class="s">"BUFGCTRL_VPR.CE1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><direct</span><span class="w"> </span><span class="na">name=</span><span class="s">"I0"</span><span class="w"> </span><span class="na">input=</span><span class="s">"BLK-TL-BUFGCTRL.I0"</span><span class="w"> </span><span class="na">output=</span><span class="s">"BUFGCTRL_VPR.I0"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><direct</span><span class="w"> </span><span class="na">name=</span><span class="s">"I1"</span><span class="w"> </span><span class="na">input=</span><span class="s">"BLK-TL-BUFGCTRL.I1"</span><span class="w"> </span><span class="na">output=</span><span class="s">"BUFGCTRL_VPR.I1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><direct</span><span class="w"> </span><span class="na">name=</span><span class="s">"IGNORE0"</span><span class="w"> </span><span class="na">input=</span><span class="s">"BLK-TL-BUFGCTRL.IGNORE0"</span><span class="w"> </span><span class="na">output=</span><span class="s">"BUFGCTRL_VPR.IGNORE0"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><direct</span><span class="w"> </span><span class="na">name=</span><span class="s">"IGNORE1"</span><span class="w"> </span><span class="na">input=</span><span class="s">"BLK-TL-BUFGCTRL.IGNORE1"</span><span class="w"> </span><span class="na">output=</span><span class="s">"BUFGCTRL_VPR.IGNORE1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><direct</span><span class="w"> </span><span class="na">name=</span><span class="s">"S0"</span><span class="w"> </span><span class="na">input=</span><span class="s">"BLK-TL-BUFGCTRL.S0"</span><span class="w"> </span><span class="na">output=</span><span class="s">"BUFGCTRL_VPR.S0"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"><direct</span><span class="w"> </span><span class="na">name=</span><span class="s">"S1"</span><span class="w"> </span><span class="na">input=</span><span class="s">"BLK-TL-BUFGCTRL.S1"</span><span class="w"> </span><span class="na">output=</span><span class="s">"BUFGCTRL_VPR.S1"</span><span class="nt">/></span> | |
| <span class="w"> </span><span class="nt"></interconnect></span> | |
| <span class="w"> </span><span class="nt"><metadata></span> | |
| <span class="w"> </span><span class="nt"><meta</span><span class="w"> </span><span class="na">name=</span><span class="s">"fasm_features"</span><span class="nt">></span> | |
| <span class="w"> </span>IN_USE | |
| <span class="w"> </span><span class="nt"></meta></span> | |
| <span class="w"> </span><span class="nt"></metadata></span> | |
| <span class="w"> </span><span class="nt"></mode></span> | |
| <span class="nt"></pb_type></span> | |
| </pre></div> | |
| </div> | |
| <p>A correctly prepared techmap for any VPR model contains a declaration of | |
| the module that should be substituted. Inside the module declaration, one | |
| should provide a necessary logic and instantiate another module that | |
| will substitute its original version. Additionally, all equations within | |
| a techmap that are not used directly in a module instantiation should evaluate | |
| to a constant value. Therefore most of the techmaps use additional constant | |
| parameters to modify the signals attached to the instantiated module.</p> | |
| <p>Here is a piece of a techmap, which instructs Yosys to convert | |
| a <code class="docutils literal notranslate"><span class="pre">BUFG</span></code> primitive to the <code class="docutils literal notranslate"><span class="pre">BUFGCTRL_VPR</span></code>. In this case, the techmaping process | |
| consists of two steps. Firstly, the techmap shows how to translate the <code class="docutils literal notranslate"><span class="pre">BUFG</span></code> | |
| primitive to the <code class="docutils literal notranslate"><span class="pre">BUFGCTRL</span></code>. Then how to translate the <code class="docutils literal notranslate"><span class="pre">BUFGCTRL</span></code> to | |
| the <code class="docutils literal notranslate"><span class="pre">BUFGCTRL_VPR</span></code>:</p> | |
| <div class="highlight-verilog notranslate"><div class="highlight"><pre><span></span><span class="k">module</span><span class="w"> </span><span class="n">BUFG</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="k">input</span><span class="w"> </span><span class="n">I</span><span class="p">,</span> | |
| <span class="w"> </span><span class="k">output</span><span class="w"> </span><span class="n">O</span> | |
| <span class="w"> </span><span class="p">);</span> | |
| <span class="w"> </span><span class="n">BUFGCTRL</span><span class="w"> </span><span class="n">_TECHMAP_REPLACE_</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">O</span><span class="p">(</span><span class="n">O</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">CE0</span><span class="p">(</span><span class="mh">1</span><span class="mb">'b1</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">CE1</span><span class="p">(</span><span class="mh">1</span><span class="mb">'b0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">I0</span><span class="p">(</span><span class="n">I</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">I1</span><span class="p">(</span><span class="mh">1</span><span class="mb">'b1</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">IGNORE0</span><span class="p">(</span><span class="mh">1</span><span class="mb">'b0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">IGNORE1</span><span class="p">(</span><span class="mh">1</span><span class="mb">'b1</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">S0</span><span class="p">(</span><span class="mh">1</span><span class="mb">'b1</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">S1</span><span class="p">(</span><span class="mh">1</span><span class="mb">'b0</span><span class="p">)</span> | |
| <span class="w"> </span><span class="p">);</span> | |
| <span class="k">endmodule</span> | |
| <span class="k">module</span><span class="w"> </span><span class="n">BUFGCTRL</span><span class="w"> </span><span class="p">(</span> | |
| <span class="k">output</span><span class="w"> </span><span class="n">O</span><span class="p">,</span> | |
| <span class="k">input</span><span class="w"> </span><span class="n">I0</span><span class="p">,</span><span class="w"> </span><span class="k">input</span><span class="w"> </span><span class="n">I1</span><span class="p">,</span> | |
| <span class="k">input</span><span class="w"> </span><span class="n">S0</span><span class="p">,</span><span class="w"> </span><span class="k">input</span><span class="w"> </span><span class="n">S1</span><span class="p">,</span> | |
| <span class="k">input</span><span class="w"> </span><span class="n">CE0</span><span class="p">,</span><span class="w"> </span><span class="k">input</span><span class="w"> </span><span class="n">CE1</span><span class="p">,</span> | |
| <span class="k">input</span><span class="w"> </span><span class="n">IGNORE0</span><span class="p">,</span><span class="w"> </span><span class="k">input</span><span class="w"> </span><span class="n">IGNORE1</span> | |
| <span class="p">);</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">INIT_OUT</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">1</span><span class="mb">'b0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">PRESELECT_I0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">1</span><span class="mb">'b0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">PRESELECT_I1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">1</span><span class="mb">'b0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">IS_IGNORE0_INVERTED</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">1</span><span class="mb">'b0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">IS_IGNORE1_INVERTED</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">1</span><span class="mb">'b0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">IS_CE0_INVERTED</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">1</span><span class="mb">'b0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">IS_CE1_INVERTED</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">1</span><span class="mb">'b0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">IS_S0_INVERTED</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">1</span><span class="mb">'b0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">IS_S1_INVERTED</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">1</span><span class="mb">'b0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_IGNORE0_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_IGNORE0_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_IGNORE1_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_IGNORE1_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_CE0_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_CE0_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_CE1_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_CE1_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_S0_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_S0_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_S1_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">parameter</span><span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_S1_</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mh">0</span><span class="p">;</span> | |
| <span class="w"> </span><span class="k">localparam</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">INV_IGNORE0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_IGNORE0_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">1</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_IGNORE0_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">IS_IGNORE0_INVERTED</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="p">);</span> | |
| <span class="w"> </span><span class="k">localparam</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">INV_IGNORE1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_IGNORE1_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">1</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_IGNORE1_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">IS_IGNORE1_INVERTED</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="p">);</span> | |
| <span class="w"> </span><span class="k">localparam</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">INV_CE0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_CE0_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">1</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_CE0_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">IS_CE0_INVERTED</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="p">);</span> | |
| <span class="w"> </span><span class="k">localparam</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">INV_CE1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_CE1_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">1</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_CE1_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">IS_CE1_INVERTED</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="p">);</span> | |
| <span class="w"> </span><span class="k">localparam</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">INV_S0</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_S0_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">1</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_S0_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">IS_S0_INVERTED</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="p">);</span> | |
| <span class="w"> </span><span class="k">localparam</span><span class="w"> </span><span class="p">[</span><span class="mh">0</span><span class="o">:</span><span class="mh">0</span><span class="p">]</span><span class="w"> </span><span class="n">INV_S1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTMSK_S1_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">1</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">_TECHMAP_CONSTVAL_S1_</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="w"> </span><span class="o">&&</span> | |
| <span class="w"> </span><span class="n">IS_S1_INVERTED</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mh">0</span><span class="p">);</span> | |
| <span class="w"> </span><span class="n">BUFGCTRL_VPR</span><span class="w"> </span><span class="p">#(</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">INIT_OUT</span><span class="p">(</span><span class="n">INIT_OUT</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">ZPRESELECT_I0</span><span class="p">(</span><span class="n">PRESELECT_I0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">ZPRESELECT_I1</span><span class="p">(</span><span class="n">PRESELECT_I1</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">IS_IGNORE0_INVERTED</span><span class="p">(</span><span class="o">!</span><span class="n">IS_IGNORE0_INVERTED</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_IGNORE0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">IS_IGNORE1_INVERTED</span><span class="p">(</span><span class="o">!</span><span class="n">IS_IGNORE1_INVERTED</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_IGNORE1</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">ZINV_CE0</span><span class="p">(</span><span class="o">!</span><span class="n">IS_CE0_INVERTED</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_CE0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">ZINV_CE1</span><span class="p">(</span><span class="o">!</span><span class="n">IS_CE1_INVERTED</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_CE1</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">ZINV_S0</span><span class="p">(</span><span class="o">!</span><span class="n">IS_S0_INVERTED</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_S0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">ZINV_S1</span><span class="p">(</span><span class="o">!</span><span class="n">IS_S1_INVERTED</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_S1</span><span class="p">)</span> | |
| <span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="n">_TECHMAP_REPLACE_</span><span class="w"> </span><span class="p">(</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">O</span><span class="p">(</span><span class="n">O</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">CE0</span><span class="p">(</span><span class="n">CE0</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_CE0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">CE1</span><span class="p">(</span><span class="n">CE1</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_CE1</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">I0</span><span class="p">(</span><span class="n">I0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">I1</span><span class="p">(</span><span class="n">I1</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">IGNORE0</span><span class="p">(</span><span class="n">IGNORE0</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_IGNORE0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">IGNORE1</span><span class="p">(</span><span class="n">IGNORE1</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_IGNORE1</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">S0</span><span class="p">(</span><span class="n">S0</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_S0</span><span class="p">),</span> | |
| <span class="w"> </span><span class="p">.</span><span class="n">S1</span><span class="p">(</span><span class="n">S1</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="n">INV_S1</span><span class="p">)</span> | |
| <span class="w"> </span><span class="p">);</span> | |
| <span class="w"> </span><span class="k">endmodule</span> | |
| </pre></div> | |
| </div> | |
| <div class="admonition note"> | |
| <p class="admonition-title">Note</p> | |
| <p>All F4PGA techmaps for Xilinx 7-Series devices use special inverter | |
| logic that converts constant 0 signals at the BEL to constant-1 signals | |
| at the site. This behavior is desired since VCC is the default signal in | |
| 7-Series and US/US+ devices. The presented solution matches the conventions | |
| used by the vendor tools and gives the opportunity to validate generated | |
| bitstreams with fasm2bels and Vivado.</p> | |
| </div> | |
| <p>Yosys provides special techmapping naming conventions for wires, | |
| parameters, and modules. The special names that start with <code class="docutils literal notranslate"><span class="pre">_TECHMAP_</span></code> | |
| can be used to force certain behavior during the techmapping process. | |
| Currently, the following special names are used in F4PGA techmaps:</p> | |
| <ul class="simple"> | |
| <li><p><code class="docutils literal notranslate"><span class="pre">_TECHMAP_REPLACE_</span></code> is used as a name for an instantiated module, which will | |
| replace the one used in the original design. This special name causes | |
| the instantiated module to inherit the name and all attributes | |
| from the module that is being replaced.</p></li> | |
| <li><p><code class="docutils literal notranslate"><span class="pre">_TECHMAP_CONSTMSK_<port_name>_</span></code> and <code class="docutils literal notranslate"><span class="pre">_TECHMAP_CONSTVAL_<port_name>_</span></code> | |
| are used together as names of parameters. The <code class="docutils literal notranslate"><span class="pre">_TECHMAP_CONSTMASK_<port_name>_</span></code> | |
| has a length of the input signal. Its bits take the value 1 if | |
| the corresponding signal bit has a constant value, or 0 otherwise. | |
| The <code class="docutils literal notranslate"><span class="pre">_TECHMAP_CONSTVAL_<port_name>_</span></code> bits store the actual constant signal | |
| values when the <code class="docutils literal notranslate"><span class="pre">_TECHMAP_CONSTMASK_<port_name>_</span></code> is equal to 1.</p></li> | |
| </ul> | |
| <p>More information about special wire, parameter, and module names can be found in | |
| <a class="reference external" href="https://yosyshq.net/yosys/files/yosys_manual.pdf#page=153">techmap section in the Yosys Manual</a>.</p> | |
| <div class="admonition note"> | |
| <p class="admonition-title">Note</p> | |
| <p>Techmapping can be used not only to change the names of the primitives | |
| but primarily to match the port declarations and express the logic behind | |
| the primitive substitution:</p> | |
| <dl class="verilog module"> | |
| <dt class="sig sig-object verilog" id="verilog-bufg"> | |
| <span class="pre">module</span> <span class="sig-name descname"><span class="pre">BUFG</span></span><span class="p"><span class="pre">(</span></span><span class="pre">output</span> <span class="sig-prename descclassname"><span class="pre">O</span></span><span class="p"><span class="pre">,</span></span> <span class="pre">input</span> <span class="sig-prename descclassname"><span class="pre">I</span></span><span class="p"><span class="pre">)</span></span><a class="headerlink" href="#verilog-bufg" title="Link to this definition">¶</a></dt> | |
| <dd></dd></dl> | |
| <dl class="verilog module"> | |
| <dt class="sig sig-object verilog" id="verilog-bufgctrl"> | |
| <span class="pre">module</span> <span class="sig-name descname"><span class="pre">BUFGCTRL</span></span><span class="p"><span class="pre">(</span></span><span class="pre">output</span> <span class="sig-prename descclassname"><span class="pre">O</span></span><span class="p"><span class="pre">,</span></span> <span class="pre">input</span> <span class="sig-prename descclassname"><span class="pre">CE0</span></span><span class="p"><span class="pre">,</span></span> <span class="pre">input</span> <span class="sig-prename descclassname"><span class="pre">CE1</span></span><span class="p"><span class="pre">,</span></span> <span class="pre">input</span> <span class="sig-prename descclassname"><span class="pre">I0</span></span><span class="p"><span class="pre">,</span></span> <span class="pre">input</span> <span class="sig-prename descclassname"><span class="pre">I1</span></span><span class="p"><span class="pre">,</span></span> <span class="pre">input</span> <span class="sig-prename descclassname"><span class="pre">IGNORE0</span></span><span class="p"><span class="pre">,</span></span> <span class="pre">input</span> <span class="sig-prename descclassname"><span class="pre">IGNORE1</span></span><span class="p"><span class="pre">,</span></span> <span class="pre">input</span> <span class="sig-prename descclassname"><span class="pre">S0</span></span><span class="p"><span class="pre">,</span></span> <span class="pre">input</span> <span class="sig-prename descclassname"><span class="pre">S1</span></span><span class="p"><span class="pre">)</span></span><a class="headerlink" href="#verilog-bufgctrl" title="Link to this definition">¶</a></dt> | |
| <dd></dd></dl> | |
| </div> | |
| </section> | |
| <section id="more-information"> | |
| <h4 id="more-information">More information<a class="headerlink" href="#more-information" title="Link to this heading">¶</a></h4> | |
| <p>Additional information about Yosys can be found on the <a class="reference external" href="https://yosyshq.net/yosys/">Yosys Project Website</a> , or in <a class="reference external" href="https://yosyshq.net/yosys/files/yosys_manual.pdf">Yosys Manual</a>. You can also compile | |
| one of the tests described in Getting Started section and watch the log file | |
| to understand which operations are performed by Yosys.</p> | |
| </section> | |
| </section> | |
| </section> | |
| <section id="place-route"> | |
| <h2 id="place-route">Place & Route<a class="headerlink" href="#place-route" title="Link to this heading">¶</a></h2> | |
| <p>The F4PGA Project uses two different tools for the PnR process - <code class="docutils literal notranslate"><span class="pre">nextpnr</span></code> and <code class="docutils literal notranslate"><span class="pre">Versatile</span> <span class="pre">Place</span> <span class="pre">and</span> <span class="pre">Route</span></code> (VPR). | |
| Both of them write their final result to a file in the <code class="docutils literal notranslate"><span class="pre">.fasm</span></code> format.</p> | |
| <section id="vpr"> | |
| <h3 id="vpr">VPR<a class="headerlink" href="#vpr" title="Link to this heading">¶</a></h3> | |
| <p>See <a class="reference external" href="https://docs.verilogtorouting.org/en/latest/vpr/">VPR ➚</a>.</p> | |
| </section> | |
| <section id="nextpnr"> | |
| <h3 id="nextpnr">nextpnr<a class="headerlink" href="#nextpnr" title="Link to this heading">¶</a></h3> | |
| <p>See <a class="extlink-gh reference external" href="https://github.com/f4pga/nextpnr">nextpnr ➚</a>.</p> | |
| </section> | |
| </section> | |
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