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template <endianness big_endian>
std::pair<const char16_t *, char *>
sse_convert_utf16_to_latin1(const char16_t *buf, size_t len,
char *latin1_output) {
const char16_t *end = buf + len;
while (end - buf >= 8) {
// Load 8 UTF-16 characters into 128-bit SSE register
__m128i in = _mm_loadu_si128(reinterpret_cast<const __m128i *>(buf));
if (!match_system(big_endian)) {
const __m128i swap =
_mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
in = _mm_shuffle_epi8(in, swap);
}
__m128i high_byte_mask = _mm_set1_epi16((int16_t)0xFF00);
if (_mm_testz_si128(in, high_byte_mask)) {
// Pack 16-bit characters into 8-bit and store in latin1_output
__m128i latin1_packed = _mm_packus_epi16(in, in);
_mm_storel_epi64(reinterpret_cast<__m128i *>(latin1_output),
latin1_packed);
// Adjust pointers for next iteration
buf += 8;
latin1_output += 8;
} else {
return std::make_pair(nullptr, reinterpret_cast<char *>(latin1_output));
}
} // while
return std::make_pair(buf, latin1_output);
}
template <endianness big_endian>
std::pair<result, char *>
sse_convert_utf16_to_latin1_with_errors(const char16_t *buf, size_t len,
char *latin1_output) {
const char16_t *start = buf;
const char16_t *end = buf + len;
while (end - buf >= 8) {
__m128i in = _mm_loadu_si128(reinterpret_cast<const __m128i *>(buf));
if (!match_system(big_endian)) {
const __m128i swap =
_mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
in = _mm_shuffle_epi8(in, swap);
}
__m128i high_byte_mask = _mm_set1_epi16((int16_t)0xFF00);
if (_mm_testz_si128(in, high_byte_mask)) {
__m128i latin1_packed = _mm_packus_epi16(in, in);
_mm_storel_epi64(reinterpret_cast<__m128i *>(latin1_output),
latin1_packed);
buf += 8;
latin1_output += 8;
} else {
// Fallback to scalar code for handling errors
for (int k = 0; k < 8; k++) {
uint16_t word = !match_system(big_endian)
? scalar::utf16::swap_bytes(buf[k])
: buf[k];
if (word <= 0xff) {
*latin1_output++ = char(word);
} else {
return std::make_pair(result(error_code::TOO_LARGE, buf - start + k),
latin1_output);
}
}
buf += 8;
}
} // while
return std::make_pair(result(error_code::SUCCESS, buf - start),
latin1_output);
}
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