Function rt_memset

src/klibc/kstring.c:39–108

 */
#ifndef RT_KLIBC_USING_USER_MEMSET
void *rt_memset(void *s, int c, rt_ubase_t count)
{
#if defined(RT_KLIBC_USING_LIBC_MEMSET)
    return memset(s, c, count);
#elif defined(RT_KLIBC_USING_TINY_MEMSET)
    char *xs = (char *)s;

    while (count--)
        *xs++ = c;

    return s;
#else

#define LBLOCKSIZE      (sizeof(rt_ubase_t))
#define UNALIGNED(X)    ((long)X & (LBLOCKSIZE - 1))
#define TOO_SMALL(LEN)  ((LEN) < LBLOCKSIZE)

    unsigned int i = 0;
    char *m = (char *)s;
    unsigned long buffer = 0;
    unsigned long *aligned_addr = RT_NULL;
    unsigned char d = (unsigned int)c & (unsigned char)(-1);  /* To avoid sign extension, copy C to an
                                unsigned variable. (unsigned)((char)(-1))=0xFF for 8bit and =0xFFFF for 16bit: word independent */

    RT_ASSERT(LBLOCKSIZE == 2 || LBLOCKSIZE == 4 || LBLOCKSIZE == 8);

    if (!TOO_SMALL(count) && !UNALIGNED(s))
    {
        /* If we get this far, we know that count is large and s is word-aligned. */
        aligned_addr = (unsigned long *)s;

        /* Store d into each char sized location in buffer so that
         * we can set large blocks quickly.
         */
        for (i = 0; i < LBLOCKSIZE; i++)
        {
            *(((unsigned char *)&buffer)+i) = d;
        }

        while (count >= LBLOCKSIZE * 4)
        {
            *aligned_addr++ = buffer;
            *aligned_addr++ = buffer;
            *aligned_addr++ = buffer;
            *aligned_addr++ = buffer;
            count -= 4 * LBLOCKSIZE;
        }

        while (count >= LBLOCKSIZE)
        {
            *aligned_addr++ = buffer;
            count -= LBLOCKSIZE;
        }

        /* Pick up the remainder with a bytewise loop. */
        m = (char *)aligned_addr;
    }