0:
  vld4.u8 { ra_x8, ga_x8, ba_x8, aa_x8 }, [colors, :128]
  vld4.u8 { rb_x8, gb_x8, bb_x8, ab_x8 }, [reference_colors, :128]!

  vmov aa2_x8, aa_x8
  vand.u8 ab_x8, ab_x8, const_31

  vceq.u8 b_kill_mask, ab_x8, #0
  vsub.u8 ai_x8, const_31, aa_x8
  vbit.u8 aa2_x8, const_31, b_kill_mask
  vbic.u8 ai_x8, ai_x8, b_kill_mask

  vmovl.u8 r_x8, ra_x8
  vmovl.u8 g_x8, ga_x8
  vmovl.u8 b_x8, ba_x8

  vmlal.u8 r_x8, ra_x8, aa2_x8
  vmlal.u8 r_x8, rb_x8, ai_x8
  vmlal.u8 g_x8, ga_x8, aa2_x8
  vmlal.u8 g_x8, gb_x8, ai_x8
  vmlal.u8 b_x8, ba_x8, aa2_x8
  vmlal.u8 b_x8, bb_x8, ai_x8

  vshrn.u16 ra_x8, r_x8, #5
  vshrn.u16 ga_x8, g_x8, #5
  vshrn.u16 ba_x8, b_x8, #5

  vst1.u32 { aa_x8 }, [pixel_alpha, :64]!
  vmax.u8 aa_x8, aa_x8, ab_x8

  vst4.u8 { ra_x8, ga_x8, ba_x8, aa_x8 }, [colors, :128]!

  subs pixels, pixels, #8
  bgt 0b