Understanding << and & operators in cache code

[globalsk]

Hello,

I'm trying to understand this fragment of code in Simplescalar's
cache.h code (I've search and look over dozens sites, including
simplescalar.com and there's no help about the coding):

/* cache access macros */
#define CACHE_TAG(cp, addr) ((addr) >> (cp)->tag_shift)
#define CACHE_SET(cp, addr) (((addr) >> (cp)->set_shift) &
(cp)->set_mask)
#define CACHE_BLK(cp, addr) ((addr) & (cp)->blk_mask)
#define CACHE_TAGSET(cp, addr) ((addr) & (cp)->tagset_mask)

I know is about shifting and moving bits around, but don't know how and
specially why is done in this way and for what.

cp is an structure for a cache
addr is a typedef qword_t (64 bits)
md_addr_t blk_mask; idem, typedef qword_t
int set_shift;
md_addr_t set_mask; /* use *after* shift */
int tag_shift;
md_addr_t tag_mask; /* use *after* shift */
md_addr_t tagset_mask; /* used for fast hit detection */

Maybe this is little information, but maybe someone with the knowledge
about caches and this type of coding can help out. Please if someone
can give a helping hand about this and links where they explain in more
detail simplescalar's code will be very appreciated.

Please forgive my syntax mistakes, english is not my mother tongue.