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1 // The MIT License
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2
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3 // Copyright (c) 2009 Massachusetts Institute of Technology
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4
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5 // Permission is hereby granted, free of charge, to any person obtaining a copy
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6 // of this software and associated documentation files (the "Software"), to deal
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7 // in the Software without restriction, including without limitation the rights
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8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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9 // copies of the Software, and to permit persons to whom the Software is
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10 // furnished to do so, subject to the following conditions:
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11
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12 // The above copyright notice and this permission notice shall be included in
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13 // all copies or substantial portions of the Software.
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14
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15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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21 // THE SOFTWARE.
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22
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23 import Connectable::*;
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24 import GetPut::*;
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25 import ClientServer::*;
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26 import FIFOF::*;
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27 import FIFO::*;
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28
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29 // Local includes
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30 `include "asim/provides/processor_library.bsh"
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31
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32 interface MemArb;
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33
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34 interface Server#(MainMemReq,MainMemResp) cache0_server;
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35 interface Server#(MainMemReq,MainMemResp) cache1_server;
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36 interface Client#(MainMemReq,MainMemResp) mmem_client;
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37
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38 endinterface
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39
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40 typedef enum { REQ0, REQ1 } ReqPtr deriving(Eq,Bits);
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41
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42 module mkMemArb( MemArb );
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43
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44 //-----------------------------------------------------------
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45 // State
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46
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47 FIFOF#(MainMemReq) req0Q <- mkBFIFOF1();
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48 FIFO#(MainMemResp) resp0Q <- mkBFIFO1();
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49
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50 FIFOF#(MainMemReq) req1Q <- mkBFIFOF1();
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51 FIFO#(MainMemResp) resp1Q <- mkBFIFO1();
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52
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53 FIFO#(MainMemReq) mreqQ <- mkBFIFO1();
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54 FIFO#(MainMemResp) mrespQ <- mkBFIFO1();
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55
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56 Reg#(ReqPtr) nextReq <- mkReg(REQ0);
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57
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58 //-----------------------------------------------------------
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59 // Some wires
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60
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61 let req0avail = req0Q.notEmpty();
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62 let req1avail = req1Q.notEmpty();
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63
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64 //-----------------------------------------------------------
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65 // Rules
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66
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67 rule chooseReq0 ( req0avail && (!req1avail || (nextReq == REQ0)) );
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68 traceTiny("mkMemArb", "memArb req0",req0Q.first());
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69
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70 // Rewrite tag field if this is a load ...
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71 MainMemReq mreq
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72 = case ( req0Q.first() ) matches
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73 tagged LoadReq .ld : return LoadReq { tag:0, addr:ld.addr };
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74 tagged StoreReq .st : return req0Q.first();
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75 endcase;
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76
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77 // Send out the request
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78 mreqQ.enq(mreq);
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79 nextReq <= REQ1;
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80 req0Q.deq();
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81
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82 endrule
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83
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84 rule chooseReq1 ( req1avail && (!req0avail || (nextReq == REQ1)) );
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85 traceTiny("mkMemArb", "memArb req1",req1Q.first);
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86
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87 // Rewrite tag field if this is a load ...
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88 MainMemReq mreq
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89 = case ( req1Q.first() ) matches
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90 tagged LoadReq .ld : return LoadReq { tag:1, addr:ld.addr };
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91 tagged StoreReq .st : return req1Q.first();
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92 endcase;
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93
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94 // Send out the request
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95 mreqQ.enq(mreq);
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96 nextReq <= REQ0;
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97 req1Q.deq();
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98
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99 endrule
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100
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101 rule returnResp;
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102 traceTiny("mkMemArb", "resp",mrespQ.first());
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103
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104 // Use tag to figure out where to send response
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105 mrespQ.deq();
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106 let tag
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107 = case ( mrespQ.first() ) matches
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108 tagged LoadResp .ld : return ld.tag;
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109 tagged StoreResp .st : return st.tag;
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110 endcase;
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111
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112 if ( tag == 0 )
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113 resp0Q.enq(mrespQ.first());
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114 else
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115 resp1Q.enq(mrespQ.first());
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116
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117 endrule
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118
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119 //-----------------------------------------------------------
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120 // Methods
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121
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122 interface Server cache0_server;
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123 interface Put request = fifofToPut(req0Q);
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124 interface Get response = fifoToGet(resp0Q);
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125 endinterface
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126
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127 interface Server cache1_server;
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128 interface Put request = fifofToPut(req1Q);
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129 interface Get response = fifoToGet(resp1Q);
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130 endinterface
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131
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132 interface Client mmem_client;
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133 interface Get request = fifoToGet(mreqQ);
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134 interface Put response = fifoToPut(mrespQ);
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135 endinterface
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136
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137 endmodule
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138
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139
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