StarletBootstrapProbe: print the SBR1 ring with --sbr1-record

The probe printed the ring's length only. StarOS's EXP-003 images put
lines in the ring that REV_TRACE has no room for (the MEM2 monitor, the
measurements), so under Dolphin nothing showed them. After the record's
summary, --sbr1-record now prints the ring's text between "SBR1 RING
BEGIN" and "SBR1 RING END" on stderr, as StarOS's Broadway loader prints
it over the Gecko on the console: at most the ring's 4032 bytes, a byte
outside printable ASCII and newline, and the backslash, written \xHH.

The formatting is in ProbeRing.h, tested by StarletProbeRingTest.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

Tools/StarletBootstrapProbe/ProbeRing.h

@@ -0,0 +1,40 @@
+// Copyright 2026 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <algorithm>
+#include <functional>
+#include <string>
+
+#include <fmt/format.h>
+
+#include "Common/CommonTypes.h"
+#include "StarOSPanicCheck.h"
+
+// The text of StarOS's SBR1 ring (StarOS crates/boot-contract, report.rs), which --sbr1-record
+// prints after the run, as StarOS's Broadway loader prints it over the Gecko on the console
+// (SBL:RING BEGIN/END). Bytes come through a callback, so the formatting is tested without a CPU.
+namespace StarletBootstrapProbe
+{
+constexpr u32 SBR1_RING = 0x40;
+constexpr u32 SBR1_RING_BYTES = SBR1_SIZE - SBR1_RING;
+
+// The ring's first `length` bytes (at most SBR1_RING_BYTES), read at their record offsets. A
+// byte outside printable ASCII and '\n', and the backslash itself, is written \xHH, so the text
+// stays printable and reads back unambiguously.
+inline std::string RingText(const std::function<u8(u32)>& read_byte, u32 length)
+{
+  std::string text;
+  const u32 end = std::min(length, SBR1_RING_BYTES);
+  for (u32 index = 0; index < end; ++index)
+  {
+    const u8 byte = read_byte(SBR1_RING + index);
+    if (byte == '\n' || (byte >= 0x20 && byte < 0x7f && byte != '\\'))
+      text += static_cast<char>(byte);
+    else
+      text += fmt::format("\\x{:02x}", byte);
+  }
+  return text;
+}
+}  // namespace StarletBootstrapProbe

Tools/StarletBootstrapProbe/StarletBootstrapProbe.cpp

@@ -19,6 +19,7 @@
 #include "Core/IOS/Starlet/StarletMemory.h"
 #include "Core/System.h"
 #include "ProbeBudget.h"
+#include "ProbeRing.h"
 #include "StarOSPanicCheck.h"
 
 namespace
@@ -306,6 +307,16 @@ int main(int argc, char** argv)
     for (u32 offset = 0; offset < SBR1_SIZE; offset += 4)
       written += memory.Read_U32(SBR1_BASE + offset) != 0;
     std::cerr << " nonzero_words " << written << '\n';
+    if (sbr1 == SBR1Mode::Record)
+    {
+      // The ring's text, as StarOS's Broadway loader prints it over the Gecko on the console;
+      // END starts its own line even when the text does not end with one.
+      const std::string ring =
+          RingText([&memory](u32 offset) { return memory.Read_U8(SBR1_BASE + offset); },
+                   memory.Read_U32(SBR1_BASE + SBR1_RING_LENGTH));
+      std::cerr << "SBR1 RING BEGIN\n"
+                << ring << (ring.empty() || ring.back() == '\n' ? "" : "\n") << "SBR1 RING END\n";
+    }
   }
   system.GetMemory().Shutdown();
   return passed ? 0 : 1;