SIMD memset

gistfile1.c

#ifdef __SSE__
#include <emmintrin.h>

static void __memset(void *ptr, int c, size_t len)
{
    int i;
    register char *p = (char *) ptr;
    for (i = 0; i < len; i++) {
        p[i] = c;
    }
}
void mymemset(void *ptr, int v, size_t len)
{
    register size_t i;
    size_t loff = ((intptr_t) ptr) % 16;
    size_t l16 = (len - loff) / 16;
    size_t lrem = len - l16 * 16 - loff;
    register char *p = (char *) ptr;
    char  c = (char) v;
    __m128i c16 = _mm_set_epi8(c, c, c, c, c, c, c, c, c, c, c, c, c, c, c, c);
    __memset(p, c, loff);
    p += loff;
    for (i = 0; i < l16; ++i) {
        _mm_store_si128((__m128i*)p, c16);
        p += 16;
    }
    __memset(p, c, lrem);
}
#endif