Entity cache_replacement_policy

Block Diagram of cache_replacement_policy

Supported policies:

Abbr.	Policies	supported
RR	round robin	not yet
RAND	random	not yet
CLOCK	clock algorithm	not yet
LRU	least recently used	YES
LFU	least frequently used	not yet

Command thruth table:

TagAccess	ReadWrite	Invalidate	Replace	Command
0			0	None
1	0	0	0	TagHit and reading a cache line
1	1	0	0	TagHit and writing a cache line
1	0	1	0	TagHit and invalidate a cache line (while reading)
1	1	1	0	TagHit and invalidate a cache line (while writing)
0		0	1	Replace cache line

In a set-associative cache, each cache-set has its own instance of this component.

The input HitWay specifies the accessed way in a fully-associative or set-associative cache.

The output ReplaceWay identifies the way which will be replaced as next by a replace command. In a set-associative cache, this is the way in a specific cache set (see above).

Generics

Name	Type	Default	Description
REPLACEMENT_POLICY	string	"LRU"
CACHE_WAYS	positive	32

Ports

Name	Type	Direction	Description
Clock	std_logic	in
Reset	std_logic	in
Replace	std_logic	in	replacement interface
ReplaceWay	std_logic_vector	out
TagAccess	std_logic	in	cacheline usage update interface
ReadWrite	std_logic	in
Invalidate	std_logic	in
HitWay	std_logic_vector	in

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