/* Darken 2 pixels.

 * rgb = rgb * ((256/4) * 4 - (alpha/4)) / ((256/4) * 4)

 */

#define DARKEN_2() \

	__m128i srcAB = _mm_unpacklo_epi8(srcABCD, _mm_setzero_si128()); \

	__m128i dstAB = _mm_unpacklo_epi8(dstABCD, _mm_setzero_si128()); \

	__m128i PUT_ALPHA_IN_FRONT_OF_RGB(srcAB, alphaAB); \

	alphaAB = _mm_srli_epi16(alphaAB, 2); /* Reduce to 64 levels of shades so the max value fits in 16 bits. */ \

	__m128i nom = _mm_sub_epi16(tr_nom_base, alphaAB); \

	dstAB = _mm_mullo_epi16(dstAB, nom); \

	dstAB = _mm_srli_epi16(dstAB, 8); \

	dstAB = _mm_packus_epi16(dstAB, dstAB);