ic. thx!
so it seems that we still have to use set_bit in a for loop to set
certain particular area, rite?
Ming
On Thu, 2005-11-10 at 09:29 +1100, Neil Brown wrote:
> On Wednesday November 9, mingz@xxxxxxxxxxx wrote:
> > could anybody help me on this? thanks!
> >
> > see if we call bitmap_zero(dst, 2), it will do *dst = 0UL and thus clear
> > whole *dst, but what if we intent to clear 2 bits? not 32bits?
>
> bitmap_zero isn't intended for zeroing just a few bits in a bitmap.
> It is for zeroing an entire bitmap, and you tell it how big the bitmap
> is. So this function will always zero at least the whole bitmap, and
> maybe a bit more. as bitmaps are always allocated as an array of
> 'unsigned long', there it no risk it over-running the space allocated.
>
> Hope that helps.
> NeilBrown
>
> >
> > static inline void bitmap_zero(unsigned long *dst, int nbits)
> > {
> > if (nbits <= BITS_PER_LONG)
> > *dst = 0UL;
> > else {
> > int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
> > memset(dst, 0, len);
> > }
> > }
> >
> >
> > Ming
> >
> >
> > -
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