Fully decouple hecl from Metaforce

- Added CStringExtras Convert functions
  (and UTF-compatible versions)
- GX header copied into Runtime
- SFX headers copied into Runtime/Audio

Runtime/CStringExtras.cpp

@@ -1,6 +1,8 @@
 #include "Runtime/CStringExtras.hpp"
 #include "Runtime/Streams/CInputStream.hpp"
 
+#include <nod/OSUTF.h>
+
 namespace metaforce {
 std::string CStringExtras::ReadString(CInputStream& in) {
   u32 strLen = in.ReadLong();
@@ -18,4 +20,78 @@ std::string CStringExtras::ReadString(CInputStream& in) {
 
   return ret;
 }
-}
+
+std::string CStringExtras::ConvertToANSI(std::u16string_view sv) {
+  std::string out;
+  out.reserve(sv.size());
+  for (const char16_t c : sv) {
+    out.push_back(static_cast<char>(c));
+  }
+  return out;
+}
+
+std::u16string CStringExtras::ConvertToUNICODE(std::string_view sv) {
+  std::u16string out;
+  out.reserve(sv.size());
+  for (const char c : sv) {
+    out.push_back(static_cast<char16_t>(c));
+  }
+  return out;
+}
+
+std::string CStringExtras::ConvertToUTF8(std::u16string_view sv) {
+  std::string out;
+  const auto* in = sv.data();
+  const auto* end = in + sv.size();
+  while (in < end) {
+    char32_t utf32 = 0;
+    const char16_t* next = OSUTF16To32(in, &utf32);
+    // TODO: bug in OSUTF
+    if (next == nullptr) {
+      utf32 = *in;
+      in++;
+    } else {
+      in = next;
+    }
+    std::array<char8_t, 4> chars8{};
+    char8_t* end8 = OSUTF32To8(utf32, chars8.data());
+    if (end8 == nullptr) {
+      continue;
+    }
+    const auto* c = chars8.data();
+    while (c < end8) {
+      out.push_back(static_cast<char>(*c));
+      c++;
+    }
+  }
+  return out;
+}
+
+std::u16string CStringExtras::ConvertToUTF16(std::string_view sv) {
+  std::u16string out;
+  const auto* in = reinterpret_cast<const char8_t*>(sv.data());
+  const auto* end = in + sv.size();
+  while (in < end) {
+    char32_t utf32 = 0;
+    const char8_t* next = OSUTF8To32(in, &utf32);
+    // TODO: bug in OSUTF
+    if (next == nullptr) {
+      utf32 = *in;
+      in++;
+    } else {
+      in = next;
+    }
+    std::array<char16_t, 2> chars16{};
+    char16_t* end16 = OSUTF32To16(utf32, chars16.data());
+    if (end16 == nullptr) {
+      continue;
+    }
+    const auto* c = chars16.data();
+    while (c < end16) {
+      out.push_back(*c);
+      c++;
+    }
+  }
+  return out;
+}
+} // namespace metaforce