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/* Returns:
- pointer to the last unprocessed character (a scalar fallback should check
the rest);
- nullptr if an error was detected.
*/
const char32_t *sse_validate_utf32le(const char32_t *input, size_t size) {
const char32_t *end = input + size;
const __m128i standardmax = _mm_set1_epi32(0x10ffff);
const __m128i offset = _mm_set1_epi32(0xffff2000);
const __m128i standardoffsetmax = _mm_set1_epi32(0xfffff7ff);
__m128i currentmax = _mm_setzero_si128();
__m128i currentoffsetmax = _mm_setzero_si128();
while (input + 4 < end) {
const __m128i in = _mm_loadu_si128((__m128i *)input);
currentmax = _mm_max_epu32(in, currentmax);
currentoffsetmax =
_mm_max_epu32(_mm_add_epi32(in, offset), currentoffsetmax);
input += 4;
}
__m128i is_zero =
_mm_xor_si128(_mm_max_epu32(currentmax, standardmax), standardmax);
if (_mm_test_all_zeros(is_zero, is_zero) == 0) {
return nullptr;
}
is_zero = _mm_xor_si128(_mm_max_epu32(currentoffsetmax, standardoffsetmax),
standardoffsetmax);
if (_mm_test_all_zeros(is_zero, is_zero) == 0) {
return nullptr;
}
return input;
}
const result sse_validate_utf32le_with_errors(const char32_t *input,
size_t size) {
const char32_t *start = input;
const char32_t *end = input + size;
const __m128i standardmax = _mm_set1_epi32(0x10ffff);
const __m128i offset = _mm_set1_epi32(0xffff2000);
const __m128i standardoffsetmax = _mm_set1_epi32(0xfffff7ff);
__m128i currentmax = _mm_setzero_si128();
__m128i currentoffsetmax = _mm_setzero_si128();
while (input + 4 < end) {
const __m128i in = _mm_loadu_si128((__m128i *)input);
currentmax = _mm_max_epu32(in, currentmax);
currentoffsetmax =
_mm_max_epu32(_mm_add_epi32(in, offset), currentoffsetmax);
__m128i is_zero =
_mm_xor_si128(_mm_max_epu32(currentmax, standardmax), standardmax);
if (_mm_test_all_zeros(is_zero, is_zero) == 0) {
return result(error_code::TOO_LARGE, input - start);
}
is_zero = _mm_xor_si128(_mm_max_epu32(currentoffsetmax, standardoffsetmax),
standardoffsetmax);
if (_mm_test_all_zeros(is_zero, is_zero) == 0) {
return result(error_code::SURROGATE, input - start);
}
input += 4;
}
return result(error_code::SUCCESS, input - start);
}
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