Fastest de-interleave operation in C?

Question

I have a pointer to an array of bytes mixed that contains the interleaved bytes of two distinct arrays array1 and array2. Say mi

Answer 1

I've only tested this lightly but it seemed at least twice as fast as your version:

typedef union {
uint16_t wide;
struct { uint8_t top; uint8_t bottom; } narrow;
} my_union;

uint16_t *source = (uint16_t *)mixed;
for (int i = 0; i < mixedLength/2; i++)
{
    my_union cursor;
    cursor.wide = source[i];
    array1[i] = cursor.narrow.top;
    array2[i] = cursor.narrow.bottom;
}

Notice that I wasn't careful with structure packing, but that in this case on this architecture that isn't a problem. Notice also someone might complain at my choice of naming top and bottom; I assume you know which half of which integers you need.