nscale8x2()

LIB8STATIC void nscale8x2	(	uint8_t &	i,
		uint8_t &	j,
		fract8	scale )

Scale two one-byte values by a third one, which is treated as the numerator of a fraction whose demominator is 256.

In other words, it computes i,j * (scale / 256).

Warning

This function always modifies its arguments in place!

Parameters

i	first value to scale
j	second value to scale
scale	scale factor, in n/256 units

Definition at line 427 of file scale8.h.

                                                                {
#if SCALE8_C == 1
#if FASTLED_SCALE8_FIXED == 1
    uint16_t scale_fixed = scale + 1;
    i = (((uint16_t)i) * scale_fixed) >> 8;
    j = (((uint16_t)j) * scale_fixed) >> 8;
#else
    i = ((uint16_t)i * (uint16_t)(scale)) >> 8;
    j = ((uint16_t)j * (uint16_t)(scale)) >> 8;
#endif
#elif SCALE8_AVRASM == 1
    i = scale8_LEAVING_R1_DIRTY(i, scale);
    j = scale8_LEAVING_R1_DIRTY(j, scale);
    cleanup_R1();
#else
#error "No implementation for nscale8x2 available."
#endif
}

References cleanup_R1(), LIB8STATIC, scale, and scale8_LEAVING_R1_DIRTY().

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