reorganize BB file loading abstractions

src/GSLArchive.cc

@@ -0,0 +1,67 @@
+#include "GSLArchive.hh"
+
+#include <phosg/Encoding.hh>
+#include <phosg/Filesystem.hh>
+#include <stdexcept>
+
+#include "Text.hh"
+
+using namespace std;
+
+
+
+// TODO: Support big-endian GSLs also (e.g. from PSO GC)
+
+struct GSLHeaderEntry {
+  ptext<char, 0x20> filename;
+  le_uint32_t offset; // In pages, so actual offset is this * 0x800
+  le_uint32_t size;
+  uint64_t unused;
+};
+
+GSLArchive::GSLArchive(shared_ptr<const string> data) : data(data) {
+  StringReader r(*this->data);
+  uint64_t min_data_offset = 0xFFFFFFFFFFFFFFFF;
+  while (r.where() < min_data_offset) {
+    const auto& entry = r.get<GSLHeaderEntry>();
+    if (entry.filename.len() == 0) {
+      break;
+    }
+    uint64_t offset = static_cast<uint64_t>(entry.offset) * 0x800;
+    if (offset + entry.size > this->data->size()) {
+      throw runtime_error("GSL entry extends beyond end of data");
+    }
+    this->entries.emplace(entry.filename, Entry{offset, entry.size});
+  }
+}
+
+const unordered_map<string, GSLArchive::Entry> GSLArchive::all_entries() const {
+  return this->entries;
+}
+
+pair<const void*, size_t> GSLArchive::get(const std::string& name) const {
+  try {
+    const auto& entry = this->entries.at(name);
+    return make_pair(this->data->data() + entry.offset, entry.size);
+  } catch (const out_of_range&) {
+    throw out_of_range("GSL does not contain file: " + name);
+  }
+}
+
+string GSLArchive::get_copy(const string& name) const {
+  try {
+    const auto& entry = this->entries.at(name);
+    return this->data->substr(entry.offset, entry.size);
+  } catch (const out_of_range&) {
+    throw out_of_range("GSL does not contain file: " + name);
+  }
+}
+
+StringReader GSLArchive::get_reader(const string& name) const {
+  try {
+    const auto& entry = this->entries.at(name);
+    return StringReader(this->data->data() + entry.offset, entry.size);
+  } catch (const out_of_range&) {
+    throw out_of_range("GSL does not contain file: " + name);
+  }
+}