Circular 4-bit rotations (for fun)

I came up with the idea of circular rotations on each *box* of 4 bits (counter-clockwise in this case) earlier today and decided to try and write a function that would save the values back to the 2 16-bit integers. It was a pretty fun thing to write

Code:

#include <stdio.h>
#include <stdint.h>

void rotate_4b(uint16_t *v1, uint16_t *v2)
{
    int n = 0;
    while (n < 16)
    {
        int swap_v1 = (((*v1 >> n) & 1) << 1) | ((*v2 >> n) & 1);
        int swap_v2 = ((*v1 >> n) & 2) | ((*v2 >> (n + 1)) & 1);
        *v1 = (*v1 & ~(3 << n)) | (swap_v1 << n);
        *v2 = (*v2 & ~(3 << n)) | (swap_v2 << n);
        n += 2;
    }
}

int main(void)
{
    int i = 0;
    uint16_t v1 = 0x0A0A;
    uint16_t v2 = 0xB0B0;

    for (; i < 4; ++i)
    {
        rotate_4b(&v1, &v2);
        printf("0x%.4x\n", v1);
        printf("0x%.4x\n\n", v2);
    }

    return 0;
}

Code:

/*
before:
0001 0010 0011 0100 = 0x1234
0101 0110 0111 1000 = 0x5678

after:
0111 0100 0111 1000 = 0x7478
0000 0011 0011 0100 = 0x0334

0 <- 1

Section is not that active, so I'll post this even though it's not terribly useful.