Add AC6 PAC extraction and texture export tooling

src/ac6_pac_decode_dump.cpp

@@ -0,0 +1,71 @@
+#include <rex/logging.h>
+
+#include <cstdlib>
+#include <filesystem>
+#include <fstream>
+#include <mutex>
+#include <sstream>
+#include <string>
+#include <string_view>
+
+namespace {
+
+bool DumpingEnabled() {
+    static const bool enabled = [] {
+        const char* value = std::getenv("AC6_DUMP_PAC_DECODED");
+        return value && value[0] && std::string_view(value) != "0";
+    }();
+    return enabled;
+}
+
+std::filesystem::path DumpRoot() {
+    return std::filesystem::path("out") / "ac6_pac_runtime_dump";
+}
+
+std::mutex& DumpMutex() {
+    static std::mutex mutex;
+    return mutex;
+}
+
+}  // namespace
+
+void Ac6DumpPacDecodedEntry(uint16_t entry_index, uint8_t codec_mode, uint32_t compressed_size,
+                            uint32_t decompressed_size, uint32_t source_offset,
+                            const uint8_t* host_data) {
+    if (!DumpingEnabled() || !host_data || decompressed_size == 0) {
+        return;
+    }
+
+    std::scoped_lock lock(DumpMutex());
+
+    std::error_code ec;
+    const auto root = DumpRoot();
+    std::filesystem::create_directories(root, ec);
+    if (ec) {
+        REXFS_ERROR("[AC6 PAC] failed to create dump directory {}: {}", root.string(), ec.message());
+        return;
+    }
+
+    std::ostringstream name;
+    name << "entry_" << entry_index << "_mode" << static_cast<uint32_t>(codec_mode) << "_c" << compressed_size
+         << "_u" << decompressed_size << "_off" << std::hex << source_offset << std::dec << ".bin";
+    const auto path = root / name.str();
+
+    std::ofstream file(path, std::ios::binary | std::ios::trunc);
+    if (!file) {
+        REXFS_ERROR("[AC6 PAC] failed to open decoded dump {}", path.string());
+        return;
+    }
+
+    file.write(reinterpret_cast<const char*>(host_data), static_cast<std::streamsize>(decompressed_size));
+    if (!file) {
+        REXFS_ERROR("[AC6 PAC] failed to write decoded dump {}", path.string());
+        return;
+    }
+
+    REXFS_INFO(
+        "[AC6 PAC] dumped decoded entry index={} mode={} compressed=0x{:x} decompressed=0x{:x} "
+        "source_offset=0x{:x} path={}",
+        entry_index, static_cast<uint32_t>(codec_mode), compressed_size, decompressed_size, source_offset,
+        path.string());
+}