Mercurial > pygar
comparison modules/bluespec/Pygar/lab1/FIRFilterDefault.bsv @ 8:74716e9a81cc pygar svn.9
[svn r9] Pygar now has the proper directory structure to play nicely with awb. Also, the apm file for audio-core willcompile successfully.
author | rlm |
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date | Fri, 23 Apr 2010 02:32:05 -0400 |
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1 // The MIT License | |
2 | |
3 // Copyright (c) 2009 Massachusetts Institute of Technology | |
4 | |
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: | |
11 | |
12 // The above copyright notice and this permission notice shall be included in | |
13 // all copies or substantial portions of the Software. | |
14 | |
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. | |
22 | |
23 // Author: Kermin Fleming kfleming@mit.edu | |
24 | |
25 import Connectable::*; | |
26 import GetPut::*; | |
27 import ClientServer::*; | |
28 import FIFO::*; | |
29 import FixedPoint::*; | |
30 import Vector::*; | |
31 | |
32 //AWB includes. These import the structure whcih allow us to communicate | |
33 // with the outside world, and are part of the AWB library code | |
34 | |
35 `include "asim/provides/soft_connections.bsh" | |
36 `include "asim/provides/common_services.bsh" | |
37 | |
38 // Local includes. Look for the correspondingly named .awb files | |
39 // workspace/labs/src/mit-6.375/modules/bluespec/mit-6.375/common/ | |
40 // to find the actual Bluespec files which are used to generate | |
41 // these includes. These files are specific to this audio processing | |
42 // pipeline | |
43 | |
44 `include "asim/provides/audio_pipeline_types.bsh" | |
45 `include "asim/provides/audio_processor_types.bsh" | |
46 | |
47 typedef 8 Taps; | |
48 | |
49 module [Connected_Module] mkFIRFilter (FIRFilter); | |
50 | |
51 | |
52 // instantiate an input FIFO and an Output FIFO | |
53 // mkFIFO returns a fifo of length 2 (by default) | |
54 // AudioProcessorUnit is the name given to the packets | |
55 // of DATA processed by our audio pipeline. For their | |
56 // definition, look in the file | |
57 // workspace/labs/src/mit-6.375/modules/bluespec/mit-6.375/common/AudioProcessorTypes.bsv | |
58 | |
59 FIFO#(AudioProcessorUnit) infifo <- mkFIFO; | |
60 FIFO#(AudioProcessorUnit) outfifo <- mkFIFO; | |
61 | |
62 | |
63 // an alternate syntax for instantiating the samples vector | |
64 // would have been as follows: | |
65 // | |
66 // Vector#(Taps,Reg#(Sample)) samples <- replicateM(mkReg(0)); | |
67 // | |
68 // we have used an explicit loop here, to demonstrate how | |
69 // vectors can be instantiated during the static elaboration | |
70 // phase, even though replicateM is far more concise. | |
71 | |
72 Vector#(Taps,Reg#(Sample)) samples = newVector(); | |
73 for(Integer i = 0; i < valueof(Taps); i=i+1) | |
74 samples[i] <- mkReg(0); | |
75 | |
76 Vector#(9,Reg#(FixedPoint#(16,16))) pr <- replicateM(mkReg(0)); | |
77 | |
78 | |
79 // fromReal takes a Real number and converts it to a FixedPoint | |
80 // representation. The compiler is smart enough to infer the | |
81 // type (bit width) of the fixed point (in this case, we have 16 | |
82 // bits of integer, and 16 bits of fraction. | |
83 | |
84 FixedPoint#(16,16) firCoefs [9] = {fromReal(-0.0124), | |
85 fromReal(0.0), | |
86 fromReal(-0.0133), | |
87 fromReal(0.0), | |
88 fromReal(0.8181), | |
89 fromReal(0.0), | |
90 fromReal(-0.0133), | |
91 fromReal(0.0), | |
92 fromReal(-0.0124)}; | |
93 | |
94 | |
95 // This rule implements a fir filter. We do the fir computations in | |
96 // 16.16 fixed point. This preserves the magnitude of the input | |
97 // pcm. This code was implemented using for loops so as to be more | |
98 // clear. Using the functions map, fold, readVReg, and writeVReg | |
99 // would have been more concise. | |
100 | |
101 rule process (infifo.first matches tagged Sample .sample); | |
102 | |
103 // Advance the fir filter, by shifting all the elements | |
104 // down the Vector of registers (like a shift register) | |
105 | |
106 samples[0] <= sample; | |
107 for(Integer i = 0; i < valueof(Taps) - 1; i = i + 1) | |
108 begin | |
109 samples[i+1] <= samples[i]; | |
110 end | |
111 | |
112 // Filter the values, using an inefficient adder chain. You will | |
113 // need to shorten the combinatorial path, by pipelining this logic. | |
114 | |
115 FixedPoint#(16,16) accumulate= firCoefs[0] * fromInt(sample); | |
116 for(Integer i = 0; i < valueof(Taps); i = i + 1) | |
117 begin | |
118 accumulate = accumulate + firCoefs[1+i] * fromInt(samples[i]); | |
119 end | |
120 | |
121 outfifo.enq(tagged Sample fxptGetInt(accumulate)); | |
122 | |
123 infifo.deq; | |
124 endrule | |
125 | |
126 // Handle the end of stream condition. Look at the two rule guards, | |
127 // these are obviously mutually exclusive. The definition of | |
128 // AudioProcessorUnit shows that it can be tagged only as a Sample, or | |
129 // EndOfFile; nothing else! | |
130 | |
131 rule endOfFile (infifo.first matches tagged EndOfFile); | |
132 | |
133 $display("FIR got end of file"); | |
134 | |
135 // Reset state for next invocation | |
136 for(Integer i = 0; i < valueof(Taps); i = i + 1) | |
137 begin | |
138 samples[i] <= 0; | |
139 pr[i] <= 0; | |
140 end | |
141 | |
142 // pass the end-of-file token down the pipeline, eventually this will | |
143 // make it back to the software side, to notify it that the stream | |
144 // has been processed completely | |
145 | |
146 outfifo.enq(infifo.first); | |
147 infifo.deq; | |
148 endrule | |
149 | |
150 | |
151 // this section connects the fifos instantiated internally to the | |
152 // externally visible interface | |
153 | |
154 interface sampleInput = fifoToPut(infifo); | |
155 interface sampleOutput = fifoToGet(outfifo); | |
156 | |
157 endmodule |