view modules/bluespec/Pygar/lab4/InstCacheBlocking.bsv @ 46:adcfa79d2c67 pygar svn.47

[svn r47] thru.c vmh which forwards sample
author punk
date Wed, 05 May 2010 12:43:51 -0400
parents 3958de09a7c1
children 61f6267cb3db
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1 // The MIT License
3 // Copyright (c) 2009 Massachusetts Institute of Technology
5 // Permission is hereby granted, free of charge, to any person obtaining a copy
6 // of this software and associated documentation files (the "Software"), to deal
7 // in the Software without restriction, including without limitation the rights
8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 // copies of the Software, and to permit persons to whom the Software is
10 // furnished to do so, subject to the following conditions:
12 // The above copyright notice and this permission notice shall be included in
13 // all copies or substantial portions of the Software.
15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
21 // THE SOFTWARE.
23 import Connectable::*;
24 import GetPut::*;
25 import ClientServer::*;
26 import RegFile::*;
27 import FIFO::*;
28 import FIFOF::*;
29 import RWire::*;
30 import Trace::*;
32 // Local includes
33 `include "asim/provides/low_level_platform_interface.bsh"
34 `include "asim/provides/soft_connections.bsh"
35 `include "asim/provides/processor_library.bsh"
36 `include "asim/provides/fpga_components.bsh"
37 `include "asim/provides/common_services.bsh"
38 `include "asim/dict/STATS_INST_CACHE.bsh"
40 interface ICache#( type req_t, type resp_t );
42 // Interface from processor to cache
43 interface Server#(req_t,resp_t) proc_server;
45 // Interface from cache to main memory
46 interface Client#(MainMemReq,MainMemResp) mmem_client;
48 // Interface for enabling/disabling statistics
49 interface Put#(Bool) statsEn_put;
51 endinterface
53 //----------------------------------------------------------------------
54 // Cache Types
55 //----------------------------------------------------------------------
57 typedef 10 CacheLineIndexSz;
58 typedef 20 CacheLineTagSz;
59 typedef 32 CacheLineSz;
61 typedef Bit#(CacheLineIndexSz) CacheLineIndex;
62 typedef Bit#(CacheLineTagSz) CacheLineTag;
63 typedef Bit#(CacheLineSz) CacheLine;
65 typedef enum
66 {
67 Init,
68 Access,
69 Evict,
70 RefillReq,
71 RefillResp
72 }
73 CacheStage
74 deriving (Eq,Bits);
76 //----------------------------------------------------------------------
77 // Helper functions
78 //----------------------------------------------------------------------
80 function Bit#(AddrSz) getAddr( InstReq req );
82 Bit#(AddrSz) addr = ?;
83 case ( req ) matches
84 tagged LoadReq .ld : addr = ld.addr;
85 tagged StoreReq .st : addr = st.addr;
86 endcase
88 return addr;
90 endfunction
92 function CacheLineIndex getCacheLineIndex( InstReq req );
93 Bit#(AddrSz) addr = getAddr(req);
94 Bit#(CacheLineIndexSz) index = truncate( addr >> 2 );
95 return index;
96 endfunction
98 function CacheLineTag getCacheLineTag( InstReq req );
99 Bit#(AddrSz) addr = getAddr(req);
100 Bit#(CacheLineTagSz) tag = truncate( addr >> fromInteger(valueOf(CacheLineIndexSz)) >> 2 );
101 return tag;
102 endfunction
104 function Bit#(AddrSz) getCacheLineAddr( InstReq req );
105 Bit#(AddrSz) addr = getAddr(req);
106 return ((addr >> 2) << 2);
107 endfunction
109 //----------------------------------------------------------------------
110 // Main module
111 //----------------------------------------------------------------------
113 module [CONNECTED_MODULE] mkInstCache( ICache#(InstReq,InstResp) );
115 //-----------------------------------------------------------
116 // State
118 Reg#(CacheStage) stage <- mkReg(Init);
120 LUTRAM#(CacheLineIndex,Maybe#(CacheLineTag)) cacheTagRam <- mkLUTRAMU_RegFile();
121 LUTRAM#(CacheLineIndex,CacheLine) cacheDataRam <- mkLUTRAMU_RegFile();
123 FIFO#(InstReq) reqQ <- mkFIFO();
124 FIFOF#(InstResp) respQ <- mkBFIFOF1();
126 FIFO#(MainMemReq) mainMemReqQ <- mkBFIFO1();
127 FIFO#(MainMemResp) mainMemRespQ <- mkFIFO();
129 Reg#(CacheLineIndex) initCounter <- mkReg(1);
131 // Statistics state
133 Reg#(Bool) statsEn <- mkReg(False);
135 STAT num_accesses <- mkStatCounter(`STATS_INST_CACHE_NUM_ACCESSES);
136 STAT num_misses <- mkStatCounter(`STATS_INST_CACHE_NUM_MISSES);
137 STAT num_evictions <- mkStatCounter(`STATS_INST_CACHE_NUM_EVICTIONS);
139 //-----------------------------------------------------------
140 // Name some wires
142 let req = reqQ.first();
143 let reqIndex = getCacheLineIndex(req);
144 let reqTag = getCacheLineTag(req);
145 let reqCacheLineAddr = getCacheLineAddr(req);
146 let refill = mainMemRespQ.first();
148 //-----------------------------------------------------------
149 // Initialize
151 rule init ( stage == Init );
152 traceTiny("mkInstCacheBlocking", "stage","i");
153 initCounter <= initCounter + 1;
154 cacheTagRam.upd(initCounter,Invalid);
155 if ( initCounter == 0 )
156 stage <= Access;
157 endrule
159 //-----------------------------------------------------------
160 // Cache access rule
162 rule access ( (stage == Access) && respQ.notFull() );
164 // Statistics
166 if ( statsEn )
167 num_accesses.incr();
169 // Check tag and valid bit to see if this is a hit or a miss
171 Maybe#(CacheLineTag) cacheLineTag = cacheTagRam.sub(reqIndex);
173 // Handle cache hits ...
175 if ( isValid(cacheLineTag) && ( unJust(cacheLineTag) == reqTag ) )
176 begin
177 traceTiny("mkInstCacheBlocking", "hitMiss","h");
178 reqQ.deq();
180 case ( req ) matches
182 tagged LoadReq .ld :
183 respQ.enq( LoadResp { tag : ld.tag, data : cacheDataRam.sub(reqIndex) } );
185 tagged StoreReq .st :
186 $display( " RTL-ERROR : %m : Stores are not allowed on the inst port!" );
188 endcase
190 end
192 // Handle cache misses - since lines in instruction cache are
193 // never dirty we can always immediately issue a refill request
195 else
196 begin
197 traceTiny("mkInstCacheBlocking", "hitMiss","m");
198 if ( statsEn )
199 num_misses.incr();
200 if ( statsEn )
201 if ( isJust(cacheLineTag) )
202 num_evictions.incr();
204 MainMemReq rfReq
205 = LoadReq { tag : 0,
206 addr : reqCacheLineAddr };
208 mainMemReqQ.enq(rfReq);
209 stage <= RefillResp;
210 end
212 endrule
214 //-----------------------------------------------------------
215 // Refill response rule
217 rule refillResp ( stage == RefillResp );
218 traceTiny("mkInstCacheBlocking", "stage","R");
219 traceTiny("mkInstCacheBlocking", "refill",refill);
221 // Write the new data into the cache and update the tag
223 mainMemRespQ.deq();
224 case ( mainMemRespQ.first() ) matches
226 tagged LoadResp .ld :
227 begin
228 cacheTagRam.upd(reqIndex,Valid(reqTag));
229 cacheDataRam.upd(reqIndex,ld.data);
230 end
232 tagged StoreResp .st :
233 noAction;
235 endcase
237 stage <= Access;
238 endrule
240 //-----------------------------------------------------------
241 // Methods
243 interface Client mmem_client;
244 interface Get request = fifoToGet(mainMemReqQ);
245 interface Put response = fifoToPut(mainMemRespQ);
246 endinterface
248 interface Server proc_server;
249 interface Put request = tracePut("mkInstCacheBlocking", "reqTiny",fifoToPut(reqQ));
250 interface Get response = traceGet("mkInstCacheBlocking", "respTiny",fifofToGet(respQ));
251 endinterface
253 interface Put statsEn_put = regToPut(statsEn);
255 endmodule