BLEND_OP
BLEND_OP(i + 0, W);
BLEND_OP(i + 1, W);
BLEND_OP(i + 2, W);
BLEND_OP(i + 3, W);
BLEND_OP(i + 4, W);
BLEND_OP(i + 5, W);
BLEND_OP(i + 6, W);
BLEND_OP(i + 7, W);