使用快速指令集来将32位RGB转为24位RGB

rbga32_to_rgb24_ssse3.c

void rbga32_to_rgb24_ssse3(uint8_t* dst, uint32_t* src, int width, int height) {
    __m128i *d = (__m128i*)dst;
    __m128i *s = (__m128i*)src;

    __m128i mask = _mm_setr_epi8(0, 1, 2, 4, 5, 6, 8, 9, 10, 12, 13, 14, -1, -1, -1, -1);
    for (int i = 0; i < width*height; i += 16) {
        __m128i sa = _mm_shuffle_epi8(_mm_load_si128(s), mask);
        __m128i sb = _mm_shuffle_epi8(_mm_load_si128(s + 1), mask);
        __m128i sc = _mm_shuffle_epi8(_mm_load_si128(s + 2), mask);
        __m128i sd = _mm_shuffle_epi8(_mm_load_si128(s + 3), mask);
        _mm_store_si128(d, _mm_or_si128(sa, _mm_slli_si128(sb, 12)));
        _mm_store_si128(d + 1, _mm_or_si128(_mm_srli_si128(sb, 4), _mm_slli_si128(sc, 8)));
        _mm_store_si128(d + 2, _mm_or_si128(_mm_srli_si128(sc, 8), _mm_slli_si128(sd, 4)));
        s += 4;
        d += 3;
    }
}