Enable the yosys flow for Gowin boards

src/OneWare.OssCadSuiteIntegration/Skills/fpga-toolchain-yosys/SKILL.md

@@ -44,8 +44,8 @@ Compile shows, grouped into Synthesis, Place & Route and Bitstream.
 | --- | --- |
 | `yosysToolchainNextPnrTool` | The `nextpnr-*` binary, e.g. `nextpnr-ice40`, `nextpnr-ecp5`, `nextpnr-himbaechel`. Must match the synth tool's family. |
 | `yosysToolchainNextPnrFlags` | Extra flags, typically the device and package selection. |
-| `yosysToolchainConstraintFileType` | `pcf` or `ccf` — the constraint format the board uses. |
-| `yosysToolchainOutputType` | `asc` or `txt` — the place & route output format the pack tool expects. |
+| `yosysToolchainConstraintFileType` | `pcf`, `ccf` or `cst` — the constraint format the board uses. `ccf` and `cst` are converted from the project's PCF file. |
+| `yosysToolchainOutputType` | `asc`, `txt` or `json` — the place & route output format the pack tool expects. |
 | `yosysToolchainNextPnrVerbose` | `true` adds `--verbose` and shows the full nextpnr output in the Output panel. Turn this on when diagnosing timing or placement problems. |
 
 ### Bitstream (pack)
@@ -54,7 +54,7 @@ Compile shows, grouped into Synthesis, Place & Route and Bitstream.
 | --- | --- |
 | `yosysToolchainPackTool` | `icepack`, `ecppack`, `gowin_pack` or `gmpack`, matching the family. |
 | `yosysToolchainPackFlags` | Extra flags for the pack tool. |
-| `packToolOutputFormat` | `bin` or `bit`. |
+| `packToolOutputFormat` | `bin`, `bit` or `fs`. |
 
 The three tool selections must agree on the FPGA family: `synth_ice40` + `nextpnr-ice40` +
 `icepack` is consistent, mixing families is not. The hardware package of a board ships correct

src/OneWare.OssCadSuiteIntegration/Tools/ConstraintFileHelper.cs

@@ -2,7 +2,24 @@ namespace OneWare.OssCadSuiteIntegration.Tools;
 
 public class ConstraintFileHelper
 {
+    [Obsolete(message: "Use ConvertPcfToCcf instead")]
     public static void Convert(string pcfPath, string ccfPath)
+    {
+        ConvertPcfToCcf(pcfPath, ccfPath);
+    }
+
+    public static void ConvertPcfToCcf(string pcfPath, string ccfPath)
+    {
+        ConvertPcf(pcfPath, ccfPath, "#", (signal, pin) => $"NET \"{signal}\" Loc = \"{pin}\";");
+    }
+
+    public static void ConvertPcfToCst(string pcfPath, string cstPath)
+    {
+        ConvertPcf(pcfPath, cstPath, "//", (signal, pin) => $"IO_LOC \"{signal}\" {pin};");
+    }
+
+    private static void ConvertPcf(string pcfPath, string targetPath, string commentPrefix,
+        Func<string, string, string> formatConstraint)
     {
         if (!File.Exists(pcfPath))
             throw new FileNotFoundException("PCF file not found", pcfPath);
@@ -23,7 +40,7 @@ public static void Convert(string pcfPath, string ccfPath)
 
             if (line.StartsWith("#"))
             {
-                result.Add(line);
+                result.Add(ReplaceCommentPrefix(line, commentPrefix));
                 continue;
             }
 
@@ -45,15 +62,20 @@ public static void Convert(string pcfPath, string ccfPath)
             var signal = parts[1];
             var pin = parts[2];
 
-            var newLine = $"NET \"{signal}\" Loc = \"{pin}\";";
+            var newLine = formatConstraint(signal, pin);
 
             if (!string.IsNullOrEmpty(comment))
-                newLine += $" {comment}";
+                newLine += $" {ReplaceCommentPrefix(comment, commentPrefix)}";
 
             result.Add(newLine);
         }
 
-        File.WriteAllLines(ccfPath, result);
+        File.WriteAllLines(targetPath, result);
+    }
+
+    private static string ReplaceCommentPrefix(string pcfComment, string commentPrefix)
+    {
+        return commentPrefix + pcfComment[1..];
     }
 
     public static void ConvertCcfToPcf(string ccfPath, string pcfPath)

src/OneWare.OssCadSuiteIntegration/ViewModels/YosysCompileSettingsViewModel.cs

@@ -111,6 +111,7 @@ public YosysCompileSettingsViewModel(UniversalFpgaProjectRoot fpgaProjectRoot, I
             defaultProperties.GetValueOrDefault("yosysToolchainConstraintFileType") ?? "", [
                 "pcf",
                 "ccf",
+                "cst"
             ])
         {
             HoverDescription = "Set NextPnr tool"
@@ -119,7 +120,8 @@ public YosysCompileSettingsViewModel(UniversalFpgaProjectRoot fpgaProjectRoot, I
         _nextPnrToolOutputTypeSetting = new ComboBoxSetting("NextPnr Output file type",
             defaultProperties.GetValueOrDefault("yosysToolchainOutputType") ?? "", [
                 "asc",
-                "txt"
+                "txt",
+                "json"
             ])
         {
             HoverDescription = "Set NextPnr tool"
@@ -151,7 +153,8 @@ public YosysCompileSettingsViewModel(UniversalFpgaProjectRoot fpgaProjectRoot, I
         _packOutputTypeSetting = new ComboBoxSetting("Pack output format",
             defaultProperties.GetValueOrDefault("packToolOutputFormat") ?? "", [
                 "bin",
-                "bit"
+                "bit",
+                "fs"
             ])
         {
             HoverDescription = "Set Pack tool output format"

src/OneWare.OssCadSuiteIntegration/Yosys/YosysService.cs

@@ -251,23 +251,21 @@ private async Task<bool> RunNextpnrAsync(UniversalFpgaProjectRoot project, FpgaM
                     builder.Add("--pcf").AddPath(pcfFile);
                     break;
                 case "ccf":
-                    var absolutePcfPath = Path.Combine(project.RootFolderPath, pcfFile);
-                    outputService.WriteLine($"Converting {absolutePcfPath} to CCF File");
-
-                    if (File.Exists(absolutePcfPath))
-                    {
-                        ConstraintFileHelper.Convert(absolutePcfPath,
-                            Path.Combine(project.RootFolderPath, "./build/constrains.ccf"));
-                    }
-                    else
-                    {
-                        outputService.WriteLine($"Could not generate CCF file from {pcfFile}");
+                    if (!ConvertConstraintFile(project, pcfFile, "./build/constrains.ccf", "CCF",
+                            ConstraintFileHelper.ConvertPcfToCcf))
                         return false;
-                    }
 
                     builder.Add("-o");
                     builder.AddScript("ccf={path}", ("{path}", "./build/constrains.ccf"));
                     break;
+                case "cst":
+                    if (!ConvertConstraintFile(project, pcfFile, "./build/constraints.cst", "CST",
+                            ConstraintFileHelper.ConvertPcfToCst))
+                        return false;
+
+                    builder.Add("-o");
+                    builder.AddScript("cst={path}", ("{path}", "./build/constraints.cst", true));
+                    break;
                 default:
                     outputService.WriteLine($"Could not find Constraint file type: {cFileType}");
                     return false;
@@ -286,6 +284,10 @@ private async Task<bool> RunNextpnrAsync(UniversalFpgaProjectRoot project, FpgaM
                     builder.Add("-o");
                     builder.AddScript("out={path}", ("{path}", pnrOutput));
                     break;
+                case "json":
+                    pnrOutput = "./build/pnr.json";
+                    builder.Add("--write").AddPath(pnrOutput);
+                    break;
                 default:
                     outputService.WriteLine($"Could not find output type: {cOutputType}");
                     return false;
@@ -354,6 +356,7 @@ public async Task<bool> AssembleAsync(UniversalFpgaProjectRoot project, FpgaMode
             {
                 "asc" => "./build/nextpnr.asc",
                 "txt" => "./build/impl.txt",
+                "json" => "./build/pnr.json",
                 _ => throw new ArgumentException($"Unsupported input type: {cOutputType}")
             };
 
@@ -371,12 +374,15 @@ public async Task<bool> AssembleAsync(UniversalFpgaProjectRoot project, FpgaMode
             {
                 "bin" => "./build/pack.bin",
                 "bit" => "./build/pack.bit",
+                "fs" => "./build/pack.fs",
                 _ => throw new ArgumentException($"Unsupported output format: {pOutputFormat}")
             };
 
             // Remove a previous result so a failing run can never be followed by a stale bitstream
             DeleteArtifact(project, outputPath);
 
+            // gowin_pack takes the output as an option, the other pack tools as the second argument
+            if (packTool == "gowin_pack") builder.Add("-o");
             builder.AddPath(outputPath);
 
             var flags = properties.GetValueOrDefault("yosysToolchainPackFlags")?.Split(' ',
@@ -440,6 +446,26 @@ public async Task<IEnumerable<FpgaNode>> ExtractNodesAsync(IProjectFile file)
         return ReadJson(Path.Combine(buildpath, "yosys_nodes.json"));
     }
 
+    /// <summary>
+    /// Converts the project's PCF file, which the constraint editor writes, into the format the nextpnr
+    /// architecture reads.
+    /// </summary>
+    private bool ConvertConstraintFile(UniversalFpgaProjectRoot project, string pcfFile, string targetFile,
+        string targetFormat, Action<string, string> convert)
+    {
+        var absolutePcfPath = Path.Combine(project.RootFolderPath, pcfFile);
+        outputService.WriteLine($"Converting {absolutePcfPath} to {targetFormat} File");
+
+        if (!File.Exists(absolutePcfPath))
+        {
+            outputService.WriteLine($"Could not generate {targetFormat} file from {pcfFile}");
+            return false;
+        }
+
+        convert(absolutePcfPath, Path.Combine(project.RootFolderPath, targetFile));
+        return true;
+    }
+
     private static bool IsErrorLine(string line)
     {
         return line.TrimStart().StartsWith("Error:", StringComparison.OrdinalIgnoreCase);