Using packed string compare from SSE4.2 to search for certain characters

try-sse.c

#include <smmintrin.h>

typedef union __attribute__((aligned(16))) {
    unsigned char bytes[16];
    __m128i vec;
} vec_bytes_128;

int main() {
    int length = 3;
    vec_bytes_128 in = { 'a', 'e', 'e', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

    vec_bytes_128 test = { '\t', '\n', '\\', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

    int skippable = _mm_cmpistri(test.vec, in.vec, 0);

    if (skippable > length)
        skippable = length;                                                    
    
    exit(skippable);
}