Function copyClamped

3ds/source/titlecache.cpp:61–69

Copies a UTF-8 string into a fixed field of `fieldLen` bytes, always leaving room for a terminating NUL. The SMDH short/long descriptions are 0x40/0x80 UTF-16 units, which can expand to more UTF-8 bytes than the field holds (Japanese/emoji titles), so the copy MUST be clamped or it overruns the packed entry. When the clamp lands mid-sequence we back off to the previous codepoint boundary so a part

    // codepoint boundary so a partial UTF-8 sequence is never written. The entry
    // is memset to 0 up front, so the unwritten tail is already the NUL padding.
    void copyClamped(u8* dst, size_t offset, const std::string& src, size_t fieldLen)
    {
        size_t n = std::min(src.length(), fieldLen - 1);
        // back off out of the middle of a multibyte sequence
        while (n > 0 && (static_cast<u8>(src[n]) & 0xC0) == 0x80) {
            n--;
        }
        std::memcpy(dst + offset, src.data(), n);
    }
}

void TitleCache::encode(u8* dst, Title& title, IconStore& icons)