Re: [PATCH] Optimise memset on i386

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

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>
> +void *
> +grub_memset (void *s, int c, grub_size_t n)
> +{
> +  unsigned char *p = (unsigned char *) s;
> +
> +  while (n--)
> +    *p++ = (unsigned char) c;
> +
> +  return s;
> +}
>   
Attached is a possible generic implementation. Not even compile-tested.
Could you test it and compare disasm of this version on i386 and glibc
i386 version. Perhaps they are equivalent. If they are for maintainance
reasons it's better to always use generic one.
> +
> +#ifndef APPLE_CC
> +void *memset (void *s, int c, grub_size_t n)
> +  __attribute__ ((alias ("grub_memset")));
> +#else
> +void *memset (void *s, int c, grub_size_t n)
> +{
> +  return grub_memset (s, c, n);
> +}
> +#endif
>
> Thanks,
>
>   


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko


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void
grub_memset (void *p, int c, grub_size_t len)
{
  grub_uint8_t pattern8 = c;
  if (len >= 3 * sizeof (unsigned long))
    {
      unsigned long patternl = 0;
      int i;
      for (i = 0; i < sizeof (unsigned long); i++)
	patternl |= ((unsigned long) pattern8) << (8 * i);
      while (len > 0 && (((grub_addr_t) p) & (sizeof (unsigned long) - 1)))
	{
	  *(grub_uint8_t *) p = pattern8;
	  p = (grub_uint8_t *) p + 1;
	}
      while (len >= sizeof (unsigned long))
	{
	  *(unsigned long *) p = patternl;
	  p = (unsigned long *) p + 1;
	}
    }
  while (len > 0)
    {
      *(grub_uint8_t *) p = pattern8;
      p = (grub_uint8_t *) p + 1;
    }
}

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