avg15()

LIB8STATIC_ALWAYS_INLINE int16_t avg15	(	int16_t	i,
		int16_t	j )

Calculate an integer average of two signed 15-bit integers (int16_t).

If the first argument is even, result is rounded down. If the first argument is odd, result is rounded up.

Parameters

i	first value to average
j	second value to average

Returns

mean average of i and j, rounded

Definition at line 328 of file math8.h.

                                                             {
#if AVG15_C == 1
    return (i >> 1) + (j >> 1) + (i & 0x1);
#elif AVG15_AVRASM == 1
    asm volatile(
        /* first divide j by 2, throwing away lowest bit */
        "asr %B[j]          \n\t"
        "ror %A[j]          \n\t"
        /* now divide i by 2, with lowest bit going into C */
        "asr %B[i]          \n\t"
        "ror %A[i]          \n\t"
        /* add j + C to i */
        "adc %A[i], %A[j]   \n\t"
        "adc %B[i], %B[j]   \n\t"
        : [i] "+r"(i)
        : [j] "r"(j));
    return i;
#else
#error "No implementation for avg15 available."
#endif
}

References LIB8STATIC_ALWAYS_INLINE.