Add msgpack wire protocol with halfsiphash checksums

picomap.cpp

@@ -1,6 +1,38 @@
 #include <stdio.h>
+#include <string.h>
+#include <vector>
 #include "pico/stdlib.h"
 #include "pico/bootrom.h"
+#include "msgpackpp.h"
+#include "halfsiphash.h"
+
+static constexpr uint8_t hash_key[8] = {};
+
+struct RebootingBootsel {
+    static constexpr int8_t ext_id = 1;
+    auto as_tuple() const { return std::tie(); }
+};
+
+struct Envelope {
+    static constexpr int8_t ext_id = 0;
+    uint32_t checksum;
+    std::vector<uint8_t> payload;
+    auto as_tuple() const { return std::tie(checksum, payload); }
+};
+
+static std::vector<uint8_t> pack_envelope(const std::vector<uint8_t> &payload) {
+    uint32_t checksum = halfsiphash::hash32(payload.data(), payload.size(), hash_key);
+    msgpackpp::packer p;
+    p.pack(Envelope{checksum, payload});
+    return p.get_payload();
+}
+
+static void send_bytes(const std::vector<uint8_t> &data) {
+    for (auto b : data) {
+        putchar(b);
+    }
+    stdio_flush();
+}
 
 int main() {
     stdio_init_all();
@@ -10,6 +42,11 @@ int main() {
         if (c == 'p') {
             printf("p");
         } else if (c == 'b') {
+            msgpackpp::packer inner;
+            inner.pack(RebootingBootsel{});
+            auto msg = pack_envelope(inner.get_payload());
+            send_bytes(msg);
+            sleep_ms(100);
             reset_usb_boot(0, 0);
         }
     }