Implement Pioasm for Go (TinyGo) (#1604)

Co-authored-by: Kenneth Bell <ken@netleap.io>
Co-authored-by: Christian Ege <ch@ege.io>

tools/pioasm/CMakeLists.txt

diff --git a/tools/pioasm/CMakeLists.txt b/tools/pioasm/CMakeLists.txt
index 00750a7..1c451ee 100644
--- a/tools/pioasm/CMakeLists.txt
+++ b/tools/pioasm/CMakeLists.txt
@@ -25,6 +25,7 @@
 target_sources(pioasm PRIVATE hex_output.cpp)
 target_sources(pioasm PRIVATE json_output.cpp)
 target_sources(pioasm PRIVATE ada_output.cpp)
+target_sources(pioasm PRIVATE go_output.cpp)
 target_sources(pioasm PRIVATE ${PIOASM_EXTRA_SOURCE_FILES})
 
 if ((CMAKE_CXX_COMPILER_ID STREQUAL "GNU") AND

tools/pioasm/go_output.cpp

diff --git a/tools/pioasm/go_output.cpp b/tools/pioasm/go_output.cpp
new file mode 100644
index 0000000..b1748d7
--- /dev/null
+++ b/tools/pioasm/go_output.cpp
@@ -0,0 +1,127 @@
+/*
+ * Copyright (c) 2024 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Contributed by the TinyGo authors.
+ * 
+ * Go generated by this assembler is compatible with TinyGo.
+ *
+ * https://tinygo.org
+ * https://github.com/tinygo-org/tinygo
+ * https://github.com/tinygo-org/pio
+ */
+
+#include <algorithm>
+#include <iostream>
+#include "output_format.h"
+#include "pio_disassembler.h"
+
+struct go_output : public output_format {
+    struct factory {
+        factory() {
+            output_format::add(new go_output());
+        }
+    };
+
+    go_output() : output_format("go") {}
+
+    std::string get_description() override {
+        return "Go file suitable for use with TinyGo. See https://github.com/tinygo-org/pio.";
+    }
+
+    void output_symbols(FILE *out, std::string prefix, const std::vector<compiled_source::symbol> &symbols) {
+        int count = 0;
+        for (const auto &s : symbols) {
+            if (!s.is_label) {
+                fprintf(out, "const %s%s = %d\n", prefix.c_str(), s.name.c_str(), s.value);
+                count++;
+            }
+        }
+        if (count) {
+            fprintf(out, "\n");
+            count = 0;
+        }
+        for (const auto &s : symbols) {
+            if (s.is_label) {
+                fprintf(out, "const %soffset_%s = %d\n", prefix.c_str(), s.name.c_str(), s.value);
+                count++;
+            }
+        }
+        if (count) {
+            fprintf(out, "\n");
+        }
+    }
+
+    void header(FILE *out, std::string msg) {
+        fprintf(out, "// %s\n\n", msg.c_str());
+    }
+
+    int output(std::string destination, std::vector<std::string> output_options,
+               const compiled_source &source) override {
+
+        FILE *out = open_single_output(destination);
+        if (!out) return 1;
+
+        header(out, "Code generated by pioasm; DO NOT EDIT.");
+        
+        // First we give priority to user's code blocks since 
+        //  1. In Go our imports always precede our code.
+        //  2. We give users the freedom to use their own PIO implementation.
+        for (const auto &program : source.programs) {
+            for(const auto& o : program.code_blocks) {
+                if (o.first == name) {
+                    for(const auto &contents : o.second) {
+                        fprintf(out, "%s", contents.c_str());
+                    }
+                }
+            }
+        }
+
+        for (const auto &program : source.programs) {
+            header(out, program.name);
+
+            std::string prefix = program.name;
+
+            fprintf(out, "const %sWrapTarget = %d\n", prefix.c_str(), program.wrap_target);
+            fprintf(out, "const %sWrap = %d\n", prefix.c_str(), program.wrap);
+            fprintf(out, "\n");
+
+            output_symbols(out, prefix, program.symbols);
+
+            fprintf(out, "var %sInstructions = []uint16{\n", prefix.c_str());
+            for (int i = 0; i < (int)program.instructions.size(); i++) {
+                const auto &inst = program.instructions[i];
+                if (i == program.wrap_target) {
+                    fprintf(out, "\t\t//     .wrap_target\n");
+                }
+                fprintf(out, "\t\t0x%04x, // %2d: %s\n", inst, i,
+                        disassemble(inst, program.sideset_bits_including_opt.get(), program.sideset_opt).c_str());
+                if (i == program.wrap) {
+                    fprintf(out, "\t\t//     .wrap\n");
+                }
+            }
+            fprintf(out, "}\n");
+            fprintf(out, "const %sOrigin = %d\n", prefix.c_str(), program.origin.get());
+            
+            fprintf(out, "func %sProgramDefaultConfig(offset uint8) pio.StateMachineConfig {\n", prefix.c_str());
+            fprintf(out, "\tcfg := pio.DefaultStateMachineConfig()\n");
+            fprintf(out, "\tcfg.SetWrap(offset+%sWrapTarget, offset+%sWrap)\n", prefix.c_str(),
+                    prefix.c_str());
+            if (program.sideset_bits_including_opt.is_specified()) {
+                fprintf(out, "\tcfg.SetSidesetParams(%d, %s, %s)\n", program.sideset_bits_including_opt.get(),
+                        program.sideset_opt ? "true" : "false",
+                        program.sideset_pindirs ? "true" : "false");
+            }
+            fprintf(out, "\treturn cfg;\n");
+            fprintf(out, "}\n\n");
+        }
+        
+        output_symbols(out, "", source.global_symbols);
+
+        if (out != stdout) { fclose(out); }
+        return 0;
+    }
+};
+
+static go_output::factory creator;