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1 | `include "ARM_Constants.v" | |
2 | ||
3 | module Memory( | |
4 | input clk, | |
5 | input Nrst, | |
6 | ||
7 | /* bus interface */ | |
8 | output reg [31:0] busaddr, | |
9 | output reg rd_req, | |
10 | output reg wr_req, | |
11 | input rw_wait, | |
12 | output reg [31:0] wr_data, | |
13 | input [31:0] rd_data, | |
14 | ||
15 | /* regfile interface */ | |
16 | output reg [3:0] st_read, | |
17 | input [31:0] st_data, | |
18 | ||
19 | /* stage inputs */ | |
20 | input inbubble, | |
21 | input [31:0] pc, | |
22 | input [31:0] insn, | |
23 | input [31:0] op0, | |
24 | input [31:0] op1, | |
25 | input [31:0] op2, | |
26 | input write_reg, | |
27 | input [3:0] write_num, | |
28 | input [31:0] write_data, | |
29 | ||
30 | /* outputs */ | |
31 | output reg outstall, | |
32 | output reg outbubble, | |
33 | output reg [31:0] outpc, | |
34 | output reg [31:0] outinsn, | |
35 | output reg out_write_reg = 1'b0, | |
36 | output reg [3:0] out_write_num = 4'bxxxx, | |
37 | output reg [31:0] out_write_data = 32'hxxxxxxxx | |
38 | ); | |
39 | ||
40 | reg [31:0] addr, raddr, next_regdata; | |
41 | reg [3:0] next_regsel, cur_reg, prev_reg; | |
42 | reg next_writeback, next_notdone, next_inc_next; | |
43 | reg [31:0] align_s1, align_s2, align_rddata; | |
44 | ||
45 | wire next_outbubble; | |
46 | wire next_write_reg; | |
47 | wire [3:0] next_write_num; | |
48 | wire [31:0] next_write_data; | |
49 | ||
50 | reg [15:0] regs, next_regs; | |
51 | reg started = 1'b0, next_started; | |
52 | ||
53 | reg notdone = 1'b0; | |
54 | reg inc_next = 1'b0; | |
55 | ||
56 | always @(posedge clk) | |
57 | begin | |
58 | outpc <= pc; | |
59 | outinsn <= insn; | |
60 | outbubble <= next_outbubble; | |
61 | out_write_reg <= next_write_reg; | |
62 | out_write_num <= next_write_num; | |
63 | out_write_data <= next_write_data; | |
64 | notdone <= next_notdone; | |
65 | inc_next <= next_inc_next; | |
66 | regs <= next_regs; | |
67 | prev_reg <= cur_reg; | |
68 | started <= next_started; | |
69 | end | |
70 | ||
71 | always @(*) | |
72 | begin | |
73 | addr = 32'hxxxxxxxx; | |
74 | raddr = 32'hxxxxxxxx; | |
75 | rd_req = 1'b0; | |
76 | wr_req = 1'b0; | |
77 | wr_data = 32'hxxxxxxxx; | |
78 | busaddr = 32'hxxxxxxxx; | |
79 | outstall = 1'b0; | |
80 | next_notdone = 1'b0; | |
81 | next_write_reg = write_reg; | |
82 | next_write_num = write_num; | |
83 | next_write_data = write_data; | |
84 | next_inc_next = 1'b0; | |
85 | next_outbubble = inbubble; | |
86 | outstall = 1'b0; | |
87 | next_regs = 16'b0; | |
88 | next_started = started; | |
89 | ||
90 | casez(insn) | |
91 | `DECODE_LDRSTR_UNDEFINED: begin end | |
92 | `DECODE_LDRSTR: begin | |
93 | if (!inbubble) begin | |
94 | next_outbubble = rw_wait; | |
95 | outstall = rw_wait | notdone; | |
96 | ||
97 | addr = insn[23] ? op0 + op1 : op0 - op1; /* up/down select */ | |
98 | raddr = insn[24] ? op0 : addr; /* pre/post increment */ | |
99 | busaddr = {raddr[31:2], 2'b0}; | |
100 | rd_req = insn[20]; | |
101 | wr_req = ~insn[20]; | |
102 | ||
103 | /* rotate to correct position */ | |
104 | align_s1 = raddr[1] ? {rd_data[15:0], rd_data[31:16]} : rd_data; | |
105 | align_s2 = raddr[0] ? {align_s1[7:0], align_s1[31:8]} : align_s1; | |
106 | /* select byte or word */ | |
107 | align_rddata = insn[22] ? {24'b0, align_s2[7:0]} : align_s2; | |
108 | ||
109 | if(!insn[20]) begin | |
110 | wr_data = insn[22] ? {4{op2[7:0]}} : op2; /* XXX need to actually store just a byte */ | |
111 | end | |
112 | else if(!inc_next) begin | |
113 | next_write_reg = 1'b1; | |
114 | next_write_num = insn[15:12]; | |
115 | next_write_data = align_rddata; | |
116 | next_inc_next = 1'b1; | |
117 | end | |
118 | else if(insn[21]) begin | |
119 | next_write_reg = 1'b1; | |
120 | next_write_num = insn[19:16]; | |
121 | next_write_data = addr; | |
122 | end | |
123 | next_notdone = rw_wait & insn[20] & insn[21]; | |
124 | end | |
125 | end | |
126 | `DECODE_LDMSTM: begin | |
127 | rd_req = insn[20]; | |
128 | wr_req = ~insn[20]; | |
129 | if(!started) begin | |
130 | next_regs = op1[15:0]; | |
131 | next_started = 1'b1; | |
132 | end | |
133 | else if(inc_next) begin | |
134 | if(insn[21]) begin | |
135 | next_write_reg = 1'b1; | |
136 | next_write_num = insn[19:16]; | |
137 | next_write_data = op0; | |
138 | end | |
139 | next_started = 1'b0; | |
140 | end | |
141 | else if(rw_wait) begin | |
142 | next_regs = regs; | |
143 | cur_reg = prev_reg; | |
144 | end | |
145 | else begin | |
146 | casez(regs) | |
147 | 16'b???????????????1: begin | |
148 | cur_reg = 4'h0; | |
149 | next_regs = regs & 16'b1111111111111110; | |
150 | end | |
151 | 16'b??????????????10: begin | |
152 | cur_reg = 4'h1; | |
153 | next_regs = regs & 16'b1111111111111100; | |
154 | end | |
155 | 16'b?????????????100: begin | |
156 | cur_reg = 4'h2; | |
157 | next_regs = regs & 16'b1111111111111000; | |
158 | end | |
159 | 16'b????????????1000: begin | |
160 | cur_reg = 4'h3; | |
161 | next_regs = regs & 16'b1111111111110000; | |
162 | end | |
163 | 16'b???????????10000: begin | |
164 | cur_reg = 4'h4; | |
165 | next_regs = regs & 16'b1111111111100000; | |
166 | end | |
167 | 16'b??????????100000: begin | |
168 | cur_reg = 4'h5; | |
169 | next_regs = regs & 16'b1111111111000000; | |
170 | end | |
171 | 16'b?????????1000000: begin | |
172 | cur_reg = 4'h6; | |
173 | next_regs = regs & 16'b1111111110000000; | |
174 | end | |
175 | 16'b????????10000000: begin | |
176 | cur_reg = 4'h7; | |
177 | next_regs = regs & 16'b1111111100000000; | |
178 | end | |
179 | 16'b???????100000000: begin | |
180 | cur_reg = 4'h8; | |
181 | next_regs = regs & 16'b1111111000000000; | |
182 | end | |
183 | 16'b??????1000000000: begin | |
184 | cur_reg = 4'h9; | |
185 | next_regs = regs & 16'b1111110000000000; | |
186 | end | |
187 | 16'b?????10000000000: begin | |
188 | cur_reg = 4'hA; | |
189 | next_regs = regs & 16'b1111100000000000; | |
190 | end | |
191 | 16'b????100000000000: begin | |
192 | cur_reg = 4'hB; | |
193 | next_regs = regs & 16'b1111000000000000; | |
194 | end | |
195 | 16'b???1000000000000: begin | |
196 | cur_reg = 4'hC; | |
197 | next_regs = regs & 16'b1110000000000000; | |
198 | end | |
199 | 16'b??10000000000000: begin | |
200 | cur_reg = 4'hD; | |
201 | next_regs = regs & 16'b1100000000000000; | |
202 | end | |
203 | 16'b?100000000000000: begin | |
204 | cur_reg = 4'hE; | |
205 | next_regs = regs & 16'b1000000000000000; | |
206 | end | |
207 | 16'b1000000000000000: begin | |
208 | cur_reg = 4'hF; | |
209 | next_regs = 16'b0; | |
210 | end | |
211 | default: begin | |
212 | cur_reg = 4'hx; | |
213 | next_regs = 16'b0; | |
214 | end | |
215 | endcase | |
216 | next_inc_next = next_regs == 16'b0; | |
217 | next_notdone = ~next_inc_next | (rw_wait & insn[20] & insn[21]); | |
218 | end | |
219 | end | |
220 | default: begin end | |
221 | endcase | |
222 | end | |
223 | endmodule |