Simplify handler signatures: return response struct, typed_handler does encoding

firmware/firmware.cpp

@@ -4,9 +4,9 @@
 std::string_view firmware_name = "picomap";
 
 static constexpr handler_entry handlers[] = {
-    {RequestPICOBOOT::ext_id, handle_picoboot},
-    {RequestInfo::ext_id, handle_info},
-    {RequestLog::ext_id, handle_log},
+    {RequestPICOBOOT::ext_id, typed_handler<RequestPICOBOOT, handle_picoboot>},
+    {RequestInfo::ext_id, typed_handler<RequestInfo, handle_info>},
+    {RequestLog::ext_id, typed_handler<RequestLog, handle_log>},
 };
 
 int main() {

firmware/include/dispatch.h

@@ -21,7 +21,7 @@ size_t typed_handler(uint32_t message_id, std::span<const uint8_t> payload, span
         return encode_response_into(out, message_id, DeviceError{1, "decode request ext_id=" +
             std::to_string(Req::ext_id) + ": msgpack error " + std::to_string(static_cast<int>(r.error()))});
     }
-    return Fn(message_id, req, out);
+    return encode_response_into(out, message_id, Fn(req));
 }
 
 void dispatch_init();

firmware/include/handlers.h

@@ -1,11 +1,9 @@
 #pragma once
-#include <cstdint>
-#include <span>
 #include <string_view>
 #include "wire.h"
 
 extern std::string_view firmware_name;
 
-size_t handle_picoboot(uint32_t message_id, std::span<const uint8_t> payload, span_writer &out);
-size_t handle_info(uint32_t message_id, std::span<const uint8_t> payload, span_writer &out);
-size_t handle_log(uint32_t message_id, std::span<const uint8_t> payload, span_writer &out);
+ResponsePICOBOOT handle_picoboot(const RequestPICOBOOT&);
+ResponseInfo handle_info(const RequestInfo&);
+ResponseLog handle_log(const RequestLog&);

firmware/lib/handlers.cpp

@@ -5,12 +5,12 @@
 #include "net.h"
 #include "debug_log.h"
 
-size_t handle_picoboot(uint32_t message_id, std::span<const uint8_t>, span_writer &out) {
+ResponsePICOBOOT handle_picoboot(const RequestPICOBOOT&) {
     dispatch_schedule_ms(100, []{ reset_usb_boot(0, 1); });
-    return encode_response_into(out, message_id, ResponsePICOBOOT{});
+    return {};
 }
 
-size_t handle_info(uint32_t message_id, std::span<const uint8_t>, span_writer &out) {
+ResponseInfo handle_info(const RequestInfo&) {
     ResponseInfo resp;
     pico_unique_board_id_t uid;
     pico_get_unique_board_id(&uid);
@@ -19,12 +19,12 @@ size_t handle_info(uint32_t message_id, std::span<const uint8_t>, span_writer &o
     resp.mac = ns.mac;
     resp.ip = ns.ip;
     resp.firmware_name = firmware_name;
-    return encode_response_into(out, message_id, resp);
+    return resp;
 }
 
-size_t handle_log(uint32_t message_id, std::span<const uint8_t>, span_writer &out) {
+ResponseLog handle_log(const RequestLog&) {
     ResponseLog resp;
     for (auto& e : dlog_drain())
         resp.entries.push_back(LogEntry{e.timestamp_us, std::move(e.message)});
-    return encode_response_into(out, message_id, resp);
+    return resp;
 }

firmware/test.cpp

@@ -97,17 +97,17 @@ static const std::unordered_map<std::string_view, test_fn> tests = {
     {"discovery", test_discovery},
 };
 
-static size_t handle_test(uint32_t message_id, const RequestTest& req, span_writer &out) {
+static ResponseTest handle_test(const RequestTest& req) {
     auto it = tests.find(req.name);
     if (it == tests.end())
-        return encode_response_into(out, message_id, ResponseTest{false, {"unknown test: " + req.name}});
-    return encode_response_into(out, message_id, it->second());
+        return {false, {"unknown test: " + req.name}};
+    return it->second();
 }
 
 static constexpr handler_entry handlers[] = {
-    {RequestPICOBOOT::ext_id, handle_picoboot},
-    {RequestInfo::ext_id, handle_info},
-    {RequestLog::ext_id, handle_log},
+    {RequestPICOBOOT::ext_id, typed_handler<RequestPICOBOOT, handle_picoboot>},
+    {RequestInfo::ext_id, typed_handler<RequestInfo, handle_info>},
+    {RequestLog::ext_id, typed_handler<RequestLog, handle_log>},
     {RequestTest::ext_id, typed_handler<RequestTest, handle_test>},
 };