Vectorized base4 numbers conversion

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <time.h>
#include <tmmintrin.h>


uint32_t str2bin(const char *s) {
    uint32_t val = 0;
    for (int i = 0; s[i]; i++)
        val = val + ((s[i] - '0') << (2*i));
    return val;
}
size_t bin2str(uint32_t val, char *s) {
    size_t i;
    for (i = 0; i < 16/* && val*/; i++) {
        s[i] = (val & 3) + '0';
        val >>= 2;
    }
    s[i] = 0;
    return i;
}

uint32_t str2bin_sse(const char *s) {
    __m128i reg = _mm_loadu_si128((__m128i*)s);
    reg = _mm_sub_epi8(reg, _mm_set1_epi8('0'));
    __m128i bit0 = _mm_slli_epi16(reg, 7);
    __m128i bit1 = _mm_slli_epi16(reg, 6);
    __m128i lower = _mm_unpacklo_epi8(bit0, bit1);
    __m128i upper = _mm_unpackhi_epi8(bit0, bit1);
    uint32_t val = _mm_movemask_epi8(upper);
    val <<= 16;
    val += _mm_movemask_epi8(lower);
    return val;
}
size_t bin2str_sse_a(uint32_t val, char *s) {
    __m128i reg = _mm_cvtsi32_si128(val);
    __m128i bytes = _mm_shuffle_epi8(reg, _mm_setr_epi8(-1, 0, -1, 0, -1, 1, -1, 1, -1, 2, -1, 2, -1, 3, -1, 3));
    __m128i even = _mm_mulhi_epu16(bytes, _mm_set1_epi32(0x00100100));  //epi16:  1<<8,  1<<4  x4 times
    __m128i odd  = _mm_mulhi_epu16(bytes, _mm_set1_epi32(0x04004000));  //epi16: 1<<14, 1<<10  x4 times
    even = _mm_and_si128(even, _mm_set1_epi16(0x0003));
    odd  = _mm_and_si128(odd , _mm_set1_epi16(0x0300));
    __m128i res = _mm_xor_si128(even, odd);
    res = _mm_add_epi8(res, _mm_set1_epi8('0'));
    _mm_storeu_si128((__m128i*)s, res);
    return 16;
}
size_t bin2str_sse_b(uint32_t val, char *s) {
    __m128i reg = _mm_cvtsi32_si128(val);
    __m128i bytes = _mm_shuffle_epi8(reg, _mm_setr_epi8(0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3));
    __m128i twobits = _mm_and_si128(bytes, _mm_set1_epi32(0xC0300C03));         //epi8: 3<<0, 3<<2, 3<<4, 3<<6  x4 times
    twobits = _mm_maddubs_epi16(twobits, _mm_set1_epi16(0x4001));               //epi8: 1<<0, 1<<6  x8 times
    __m128i res = _mm_madd_epi16(twobits, _mm_set1_epi32(0x10000001));          //epi16: 1<<0, 1<<12  x4 times
    res = _mm_add_epi8(res, _mm_set1_epi8('0'));
    _mm_storeu_si128((__m128i*)s, res);
    return 16;
}


int main() {
    srand(time(0));
    for (int i = 0; i < 70; i++) {
        uint32_t num = rand();
        num <<= 15;
        num ^= rand();
        num <<= 15;
        num ^= rand();
        num <<= 15;
        num ^= rand();

        char str[20];
        bin2str_sse_b(num, str);
        uint32_t val;
        val = str2bin_sse(str);

        printf("%08X %s %08X   %s\n", num, str, val, (num == val ? "" : "!"));
    }

    return 0;
}