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[/] [rtf65002/] [trunk/] [rtl/] [verilog/] [decode.v] - Blame information for rev 21

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1 20 robfinch 
// ============================================================================
2 
//        __
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//   \\__/ o\    (C) 2013  Robert Finch, Stratford
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//    \  __ /    All rights reserved.
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//     \/_//     robfinch<remove>@opencores.org
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//       ||
7 
//
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// This source file is free software: you can redistribute it and/or modify
9 
// it under the terms of the GNU Lesser General Public License as published
10 
// by the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
12 
//
13 
// This source file is distributed in the hope that it will be useful,
14 
// but WITHOUT ANY WARRANTY; without even the implied warranty of
15 
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program.  If not, see <http://www.gnu.org/licenses/>.
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//
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// ============================================================================
22 
//
23 
DECODE:
24 
        begin
25 
                first_ifetch <= `TRUE;
26 
                Rt <= 4'h0;             // Default
27 
                state <= IFETCH;
28 
                case(ir[7:0])
29 
                `STP:   begin clk_en <= 1'b0; pc <= pc + 32'd1; end
30 
                `NOP:   begin pc <= pc + 32'd1; end
31 
                `CLC:   begin cf <= 1'b0; pc <= pc + 32'd1; end
32 
                `SEC:   begin cf <= 1'b1; pc <= pc + 32'd1; end
33 
                `CLV:   begin vf <= 1'b0; pc <= pc + 32'd1; end
34 
                `CLI:   begin im <= 1'b0; pc <= pc + 32'd1; end
35 
                `CLD:   begin df <= 1'b0; pc <= pc + 32'd1; end
36 
                `SED:   begin df <= 1'b1; pc <= pc + 32'd1; end
37 
                `SEI:   begin im <= 1'b1; pc <= pc + 32'd1; end
38 
                `WAI:   begin wai <= 1'b1; pc <= pc + 32'd1; end
39 
                `EMM:   begin em <= 1'b1; pc <= pc + 32'd1; end
40 
                `DEX:   begin res <= x - 32'd1; pc <= pc + 32'd1; end
41 
                `INX:   begin res <= x + 32'd1; pc <= pc + 32'd1; end
42 
                `DEY:   begin res <= y - 32'd1; pc <= pc + 32'd1; end
43 
                `INY:   begin res <= y + 32'd1; pc <= pc + 32'd1; end
44 
                `DEA:   begin res <= acc - 32'd1; pc <= pc + 32'd1; end
45 
                `INA:   begin res <= acc + 32'd1; pc <= pc + 32'd1; end
46 
                `TSX:   begin res <= isp; pc <= pc + 32'd1; end
47 
                `TXS,`TXA,`TXY: begin res <= x; pc <= pc + 32'd1; end
48 
                `TAX,`TAY,`TAS: begin res <= acc; pc <= pc + 32'd1; end
49 
                `TYA,`TYX:      begin res <= y; pc <= pc + 32'd1; end
50 
                `TRS:           begin
51 
                                                res <= rfoa; pc <= pc + 32'd2; end
52 
                `TSR:           begin
53 
                                                Rt <= ir[15:12];
54 
                                                case(ir[11:8])
55 
                                                4'h0:   res <= {write_allocate,dcacheOn,icacheOn};
56 
                                                4'h1:   res <= dp;
57 
                                                4'h2:   res <= prod[31:0];
58 
                                                4'h3:   res <= prod[63:32];
59 
                                                4'h4:   res <= tick;
60 
                                                4'h5:   begin res <= lfsr; lfsr <= {lfsr[30:0],lfsr_fb}; end
61 
                                                4'h6:   res <= dp8;
62 
                                                4'h7:   res <= abs8;
63 
                                                4'h8:   res <= {vbr[31:1],nmoi};
64 
                                                4'hE:   res <= {spage[31:8],sp};
65 
                                                4'hF:   res <= isp;
66 
                                                endcase
67 
                                                pc <= pc + 32'd2;
68 
                                        end
69 
                `ASL_ACC:       begin res <= {acc,1'b0}; pc <= pc + 32'd1; end
70 
                `ROL_ACC:       begin res <= {acc,cf}; pc <= pc + 32'd1; end
71 
                `LSR_ACC:       begin res <= {acc[0],1'b0,acc[31:1]}; pc <= pc + 32'd1; end
72 
                `ROR_ACC:       begin res <= {acc[0],cf,acc[31:1]}; pc <= pc + 32'd1; end
73 
 
74 
                `RR:
75 
                        begin
76 
                                state <= IFETCH;
77 
                                case(ir[23:20])
78 21 robfinch 
                                `ADD_RR:        begin res <= rfoa + rfob + {31'b0,df&cf}; a <= rfoa; b <= rfob; end
79 
                                `SUB_RR:        begin res <= rfoa - rfob - {31'b0,df&~cf&|ir[19:16]}; a <= rfoa; b <= rfob; end
80 20 robfinch 
                                `AND_RR:        begin res <= rfoa & rfob; a <= rfoa; b <= rfob; end     // for bit flags
81 
                                `OR_RR:         begin res <= rfoa | rfob; a <= rfoa; b <= rfob; end
82 
                                `EOR_RR:        begin res <= rfoa ^ rfob; a <= rfoa; b <= rfob; end
83 
                                `MUL_RR:        begin state <= MULDIV1; end
84 
                                `MULS_RR:       begin state <= MULDIV1; end
85 
                                `DIV_RR:        begin state <= MULDIV1; end
86 
                                `DIVS_RR:       begin state <= MULDIV1; end
87 
                                `MOD_RR:        begin state <= MULDIV1; end
88 
                                `MODS_RR:       begin state <= MULDIV1; end
89 
                                `ASL_RRR:       begin a <= rfoa; b <= rfob; state <= CALC; end
90 
                                `LSR_RRR:       begin a <= rfoa; b <= rfob; state <= CALC; end
91 
                                endcase
92 
                                Rt <= ir[19:16];
93 
                                pc <= pc + 32'd3;
94 
                        end
95 
                `LD_RR:         begin res <= rfoa; Rt <= ir[15:12]; pc <= pc + 32'd2; end
96 
                `ASL_RR:        begin res <= {rfoa,1'b0}; pc <= pc + 32'd2; Rt <= ir[15:12]; end
97 
                `ROL_RR:        begin res <= {rfoa,cf}; pc <= pc + 32'd2; Rt <= ir[15:12]; end
98 
                `LSR_RR:        begin res <= {rfoa[0],1'b0,rfoa[31:1]}; pc <= pc + 32'd2; Rt <= ir[15:12]; end
99 
                `ROR_RR:        begin res <= {rfoa[0],cf,rfoa[31:1]}; pc <= pc + 32'd2; Rt <= ir[15:12]; end
100 
                `DEC_RR:        begin res <= rfoa - 32'd1; pc <= pc + 32'd2; Rt <= ir[15:12]; end
101 
                `INC_RR:        begin res <= rfoa + 32'd1; pc <= pc + 32'd2; Rt <= ir[15:12]; end
102 
 
103 21 robfinch 
                `ADD_IMM8:      begin res <= rfoa + {{24{ir[23]}},ir[23:16]} + {31'b0,df&cf}; Rt <= ir[15:12]; pc <= pc + 32'd3; a <= rfoa; b <= {{24{ir[23]}},ir[23:16]}; end
104 
                `SUB_IMM8:      begin res <= rfoa - {{24{ir[23]}},ir[23:16]} - {31'b0,df&~cf&|ir[15:12]}; Rt <= ir[15:12]; pc <= pc + 32'd3; a <= rfoa; b <= {{24{ir[23]}},ir[23:16]}; end
105 20 robfinch 
                `OR_IMM8:       begin res <= rfoa | {{24{ir[23]}},ir[23:16]}; Rt <= ir[15:12]; pc <= pc + 32'd3; b <= {{24{ir[23]}},ir[23:16]}; end
106 
                `AND_IMM8:      begin res <= rfoa & {{24{ir[23]}},ir[23:16]}; Rt <= ir[15:12]; pc <= pc + 32'd3; b <= {{24{ir[23]}},ir[23:16]}; end
107 
                `EOR_IMM8:      begin res <= rfoa ^ {{24{ir[23]}},ir[23:16]}; Rt <= ir[15:12]; pc <= pc + 32'd3; b <= {{24{ir[23]}},ir[23:16]}; end
108 
                `CMP_IMM8:      begin res <= acc - {{24{ir[15]}},ir[15:8]}; Rt <= 4'h0; pc <= pc + 32'd2; b <= {{24{ir[15]}},ir[15:8]}; end
109 
                `ASL_IMM8:      begin a <= rfoa; b <= ir[20:16]; Rt <= ir[15:12]; pc <= pc + 32'd3; state <= CALC; end
110 
                `LSR_IMM8:      begin a <= rfoa; b <= ir[20:16]; Rt <= ir[15:12]; pc <= pc + 32'd3; state <= CALC; end
111 
 
112 21 robfinch 
                `ADD_IMM16:     begin res <= rfoa + {{16{ir[31]}},ir[31:16]} + {31'b0,df&cf}; Rt <= ir[15:12]; pc <= pc + 32'd4; a <= rfoa; b <= {{16{ir[31]}},ir[31:16]}; end
113 
                `SUB_IMM16:     begin res <= rfoa - {{16{ir[31]}},ir[31:16]} - {31'b0,df&~cf&|ir[15:12]}; Rt <= ir[15:12]; pc <= pc + 32'd4; a <= rfoa; b <= {{16{ir[31]}},ir[31:16]}; end
114 20 robfinch 
                `OR_IMM16:      begin res <= rfoa | {{16{ir[31]}},ir[31:16]}; Rt <= ir[15:12]; pc <= pc + 32'd4; b <= {{16{ir[31]}},ir[31:16]}; end
115 
                `AND_IMM16:     begin res <= rfoa & {{16{ir[31]}},ir[31:16]}; Rt <= ir[15:12]; pc <= pc + 32'd4; b <= {{16{ir[31]}},ir[31:16]}; end
116 
                `EOR_IMM16:     begin res <= rfoa ^ {{16{ir[31]}},ir[31:16]}; Rt <= ir[15:12]; pc <= pc + 32'd4; b <= {{16{ir[31]}},ir[31:16]}; end
117 
 
118 21 robfinch 
                `ADD_IMM32:     begin res <= rfoa + ir[47:16]; Rt <= ir[15:12] + {31'b0,df&cf}; pc <= pc + 32'd6; a <= rfoa; b <= ir[47:16]; end
119 
                `SUB_IMM32:     begin res <= rfoa - ir[47:16]; Rt <= ir[15:12] - {31'b0,df&~cf&|ir[15:12]}; pc <= pc + 32'd6; a <= rfoa; b <= ir[47:16]; end
120 20 robfinch 
                `OR_IMM32:      begin res <= rfoa | ir[47:16]; Rt <= ir[15:12]; pc <= pc + 32'd6; b <= ir[47:16]; end
121 
                `AND_IMM32:     begin res <= rfoa & ir[47:16]; Rt <= ir[15:12]; pc <= pc + 32'd6; b <= ir[47:16]; end
122 
                `EOR_IMM32:     begin res <= rfoa ^ ir[47:16]; Rt <= ir[15:12]; pc <= pc + 32'd6; b <= ir[47:16]; end
123 
 
124 
                `LDX_IMM32,`LDY_IMM32,`LDA_IMM32:       begin res <= ir[39:8]; pc <= pc + 32'd5; end
125 
                `LDX_IMM16,`LDA_IMM16:  begin res <= {{16{ir[23]}},ir[23:8]}; pc <= pc + 32'd3; end
126 
                `LDX_IMM8,`LDA_IMM8: begin res <= {{24{ir[15]}},ir[15:8]}; pc <= pc + 32'd2; end
127 
 
128 
                `LDX_ZPX,`LDY_ZPX:
129 
                        begin
130 
                                radr <= zpx32xy_address;
131 
                                pc <= pc + 32'd3;
132 21 robfinch 
                                load_what <= `WORD_311;
133 
                                state <= LOAD_MAC1;
134 20 robfinch 
                        end
135 
                `ORB_ZPX:
136 
                        begin
137 
                                a <= rfoa;
138 
                                Rt <= ir[19:16];
139 
                                radr <= zpx32_address[31:2];
140 
                                radr2LSB <= zpx32_address[1:0];
141 
                                pc <= pc + 32'd4;
142 21 robfinch 
                                load_what <= `WORD_310;
143 
                                state <= LOAD_MAC1;
144 20 robfinch 
                        end
145 
                `LDX_ABS,`LDY_ABS:
146 
                        begin
147 
                                radr <= ir[39:8];
148 
                                pc <= pc + 32'd5;
149 21 robfinch 
                                load_what <= `WORD_311;
150 
                                state <= LOAD_MAC1;
151 20 robfinch 
                        end
152 
                `ORB_ABS:
153 
                        begin
154 
                                a <= rfoa;
155 
                                Rt <= ir[15:12];
156 
                                radr <= ir[47:18];
157 
                                radr2LSB <= ir[17:16];
158 
                                pc <= pc + 32'd6;
159 21 robfinch 
                                load_what <= `WORD_310;
160 
                                state <= LOAD_MAC1;
161 20 robfinch 
                        end
162 
                `LDX_ABSY,`LDY_ABSX:
163 
                        begin
164 
                                radr <= absx32xy_address;
165 
                                pc <= pc + 32'd6;
166 21 robfinch 
                                load_what <= `WORD_311;
167 
                                state <= LOAD_MAC1;
168 20 robfinch 
                        end
169 
                `ORB_ABSX:
170 
                        begin
171 
                                a <= rfoa;
172 
                                Rt <= ir[19:16];
173 
                                radr <= absx32_address[31:2];
174 
                                radr2LSB <= absx32_address[1:0];
175 
                                pc <= pc + 32'd7;
176 21 robfinch 
                                load_what <= `WORD_310;
177 
                                state <= LOAD_MAC1;
178 20 robfinch 
                        end
179 
                `ST_ZPX:
180 
                        begin
181 
                                wadr <= zpx32_address;
182 
                                wdat <= rfoa;
183 
                                pc <= pc + 32'd4;
184 
                                state <= STORE1;
185 
                        end
186 
                `STB_ZPX:
187 
                        begin
188 
                                wadr <= zpx32_address[31:2];
189 
                                wadr2LSB <= zpx32_address[1:0];
190 
                                pc <= pc + 32'd4;
191 
                                state <= STORE1;
192 
                        end
193 
                `ST_ABS:
194 
                        begin
195 
                                wadr <= ir[47:16];
196 
                                wdat <= rfoa;
197 
                                pc <= pc + 32'd6;
198 
                                state <= STORE1;
199 
                        end
200 
                `STB_ABS:
201 
                        begin
202 
                                wadr <= ir[47:18];
203 
                                wadr2LSB <= ir[17:16];
204 
                                wdat <= {4{rfoa[7:0]}};
205 
                                pc <= pc + 32'd6;
206 
                                state <= STORE1;
207 
                        end
208 
                `ST_ABSX:
209 
                        begin
210 
                                wadr <= absx32_address;
211 
                                wdat <= rfoa;
212 
                                pc <= pc + 32'd7;
213 
                                state <= STORE1;
214 
                        end
215 
                `STB_ABSX:
216 
                        begin
217 
                                wadr <= absx32_address[31:2];
218 
                                wadr2LSB <= absx32_address[1:0];
219 
                                wdat <= {4{rfoa[7:0]}};
220 
                                pc <= pc + 32'd7;
221 
                                state <= STORE1;
222 
                        end
223 
                `STX_ZPX:
224 
                        begin
225 
                                wadr <= dp + ir[23:12] + rfoa;
226 
                                wdat <= x;
227 
                                pc <= pc + 32'd3;
228 
                                state <= STORE1;
229 
                        end
230 
                `STX_ABS:
231 
                        begin
232 
                                wadr <= ir[39:8];
233 
                                wdat <= x;
234 
                                pc <= pc + 32'd5;
235 
                                state <= STORE1;
236 
                        end
237 
                `STY_ZPX:
238 
                        begin
239 
                                wadr <= dp + ir[23:12] + rfoa;
240 
                                wdat <= y;
241 
                                pc <= pc + 32'd3;
242 
                                state <= STORE1;
243 
                        end
244 
                `STY_ABS:
245 
                        begin
246 
                                wadr <= ir[39:8];
247 
                                wdat <= y;
248 
                                pc <= pc + 32'd5;
249 
                                state <= STORE1;
250 
                        end
251 
                `ADD_ZPX,`SUB_ZPX,`OR_ZPX,`AND_ZPX,`EOR_ZPX:
252 
                        begin
253 
                                a <= rfoa;
254 
                                Rt <= ir[19:16];
255 
                                radr <= zpx32_address;
256 
                                pc <= pc + 32'd4;
257 21 robfinch 
                                load_what <= `WORD_310;
258 
                                state <= LOAD_MAC1;
259 20 robfinch 
                        end
260 
                `ASL_ZPX,`ROL_ZPX,`LSR_ZPX,`ROR_ZPX,`INC_ZPX,`DEC_ZPX:
261 
                        begin
262 
                                radr <= dp + rfoa + ir[23:12];
263 
                                pc <= pc + 32'd3;
264 21 robfinch 
                                load_what <= `WORD_310;
265 
                                state <= LOAD_MAC1;
266 20 robfinch 
                        end
267 
                `ADD_IX,`SUB_IX,`OR_IX,`AND_IX,`EOR_IX,`ST_IX:
268 
                        begin
269 
                                a <= rfoa;
270 
                                if (ir[7:0]==`ST_IX)
271 
                                        res <= rfoa;            // for ST_IX, Rt=0
272 
                                else
273 
                                        Rt <= ir[19:16];
274 
                                pc <= pc + 32'd4;
275 
                                radr <= dp + ir[31:20] + rfob;
276 21 robfinch 
                                load_what <= `IA_310;
277 
                                state <= LOAD_MAC1;
278 20 robfinch 
                        end
279 
                `ADD_RIND,`SUB_RIND,`OR_RIND,`AND_RIND,`EOR_RIND,`ST_RIND:
280 
                        begin
281 
                                radr <= rfob;
282 
                                wadr <= rfob;           // for store
283 
                                wdat <= rfoa;
284 
                                a <= rfoa;
285 
                                if (ir[7:0]==`ST_RIND) begin
286 
                                        res <= rfoa;            // for ST_IX, Rt=0
287 
                                        pc <= pc + 32'd2;
288 
                                        state <= STORE1;
289 
                                end
290 
                                else begin
291 
                                        Rt <= ir[19:16];
292 
                                        pc <= pc + 32'd3;
293 21 robfinch 
                                        load_what <= `WORD_310;
294 
                                        state <= LOAD_MAC1;
295 20 robfinch 
                                end
296 
                        end
297 
                `ADD_IY,`SUB_IY,`OR_IY,`AND_IY,`EOR_IY,`ST_IY:
298 
                        begin
299 
                                a <= rfoa;
300 
                                if (ir[7:0]==`ST_IY)
301 
                                        res <= rfoa;            // for ST_IY, Rt=0
302 
                                else
303 
                                        Rt <= ir[19:16];
304 
                                pc <= pc + 32'd4;
305 21 robfinch 
                                isIY <= 1'b1;
306 20 robfinch 
                                radr <= dp + ir[31:20];
307 21 robfinch 
                                load_what <= `IA_310;
308 
                                state <= LOAD_MAC1;
309 20 robfinch 
                        end
310 
                `ADD_ABS,`SUB_ABS,`OR_ABS,`AND_ABS,`EOR_ABS:
311 
                        begin
312 
                                a <= rfoa;
313 
                                radr <= ir[47:16];
314 
                                Rt <= ir[15:12];
315 
                                pc <= pc + 32'd6;
316 21 robfinch 
                                load_what <= `WORD_310;
317 
                                state <= LOAD_MAC1;
318 20 robfinch 
                        end
319 
                `ASL_ABS,`ROL_ABS,`LSR_ABS,`ROR_ABS,`INC_ABS,`DEC_ABS:
320 
                        begin
321 
                                radr <= ir[39:8];
322 
                                pc <= pc + 32'd5;
323 21 robfinch 
                                load_what <= `WORD_310;
324 
                                state <= LOAD_MAC1;
325 20 robfinch 
                        end
326 
                `ADD_ABSX,`SUB_ABSX,`OR_ABSX,`AND_ABSX,`EOR_ABSX:
327 
                        begin
328 
                                a <= rfoa;
329 
                                radr <= ir[55:24] + rfob;
330 
                                Rt <= ir[19:16];
331 
                                pc <= pc + 32'd7;
332 21 robfinch 
                                load_what <= `WORD_310;
333 
                                state <= LOAD_MAC1;
334 20 robfinch 
                        end
335 
                `ASL_ABSX,`ROL_ABSX,`LSR_ABSX,`ROR_ABSX,`INC_ABSX,`DEC_ABSX:
336 
                        begin
337 
                                radr <= ir[47:16] + rfob;
338 
                                pc <= pc + 32'd6;
339 21 robfinch 
                                load_what <= `WORD_310;
340 
                                state <= LOAD_MAC1;
341 20 robfinch 
                        end
342 
                `CPX_IMM32:
343 
                        begin
344 
                                res <= x - ir[39:8];
345 
                                pc <= pc + 32'd5;
346 
                                state <= IFETCH;
347 
                        end
348 
                `CPY_IMM32:
349 
                        begin
350 
                                res <= y - ir[39:8];
351 
                                pc <= pc + 32'd5;
352 
                                state <= IFETCH;
353 
                        end
354 
                `CPX_ZPX:
355 
                        begin
356 
                                radr <= dp + ir[23:12] + rfoa;
357 
                                pc <= pc + 32'd3;
358 21 robfinch 
                                load_what <= `WORD_310;
359 
                                state <= LOAD_MAC1;
360 20 robfinch 
                        end
361 
                `CPY_ZPX:
362 
                        begin
363 
                                radr <= dp + ir[23:12] + rfoa;
364 
                                pc <= pc + 32'd3;
365 21 robfinch 
                                load_what <= `WORD_310;
366 
                                state <= LOAD_MAC1;
367 20 robfinch 
                        end
368 
                `CPX_ABS:
369 
                        begin
370 
                                radr <= ir[39:8];
371 
                                pc <= pc + 32'd5;
372 21 robfinch 
                                load_what <= `WORD_310;
373 
                                state <= LOAD_MAC1;
374 20 robfinch 
                        end
375 
                `CPY_ABS:
376 
                        begin
377 
                                radr <= ir[39:8];
378 
                                pc <= pc + 32'd5;
379 21 robfinch 
                                load_what <= `WORD_310;
380 
                                state <= LOAD_MAC1;
381 20 robfinch 
                        end
382 
                `BRK:
383 
                        begin
384 
                                bf <= 1'b1;
385 
                                radr <= isp_dec;
386 
                                wadr <= isp_dec;
387 
                                wdat <= pc + 32'd1;
388 
                                cyc_o <= 1'b1;
389 
                                stb_o <= 1'b1;
390 
                                we_o <= 1'b1;
391 
                                sel_o <= 4'hF;
392 
                                adr_o <= {isp_dec,2'b00};
393 
                                dat_o <= pc + 32'd1;
394 
                                vect <= {vbr[31:9],`BRK_VECTNO,2'b00};
395 
                                state <= IRQ1;
396 
                        end
397 21 robfinch 
                `INT0,`INT1:
398 
                        begin
399 
                                radr <= isp_dec;
400 
                                wadr <= isp_dec;
401 
                                wdat <= pc + 32'd2;
402 
                                cyc_o <= 1'b1;
403 
                                stb_o <= 1'b1;
404 
                                we_o <= 1'b1;
405 
                                sel_o <= 4'hF;
406 
                                adr_o <= {isp_dec,2'b00};
407 
                                dat_o <= pc + 32'd2;
408 
                                vect <= {vbr[31:9],ir[15:7],2'b00};
409 
                                state <= IRQ1;
410 
                        end
411 20 robfinch 
                `JMP:
412 
                        begin
413 
                                pc[15:0] <= ir[23:8];
414 
                                state <= IFETCH;
415 
                        end
416 
                `JML:
417 
                        begin
418 
                                pc <= ir[39:8];
419 
                                state <= IFETCH;
420 
                        end
421 
                `JMP_IND:
422 
                        begin
423 
                                radr <= ir[39:8];
424 21 robfinch 
                                load_what <= `PC_310;
425 
                                state <= LOAD_MAC1;
426 20 robfinch 
                        end
427 
                `JMP_INDX:
428 
                        begin
429 
                                radr <= ir[39:8] + x;
430 21 robfinch 
                                load_what <= `PC_310;
431 
                                state <= LOAD_MAC1;
432 20 robfinch 
                        end
433 
                `JMP_RIND:
434 
                        begin
435 
                                pc <= rfoa;
436 
                                res <= pc + 32'd2;
437 
                                Rt <= ir[15:12];
438 
                                state <= IFETCH;
439 
                        end
440 
                `JSR:
441 
                        begin
442 
                                radr <= isp_dec;
443 
                                wadr <= isp_dec;
444 
                                wdat <= pc + 32'd3;
445 
                                cyc_o <= 1'b1;
446 
                                stb_o <= 1'b1;
447 
                                we_o <= 1'b1;
448 
                                sel_o <= 4'hF;
449 
                                adr_o <= {isp_dec,2'b00};
450 
                                dat_o <= pc + 32'd3;
451 
                                vect <= {pc[31:16],ir[23:8]};
452 
                                state <= JSR1;
453 
                        end
454 
                `JSR_RIND:
455 
                        begin
456 
                                radr <= isp_dec;
457 
                                wadr <= isp_dec;
458 
                                wdat <= pc + 32'd2;
459 
                                cyc_o <= 1'b1;
460 
                                stb_o <= 1'b1;
461 
                                we_o <= 1'b1;
462 
                                sel_o <= 4'hF;
463 
                                adr_o <= {isp_dec,2'b00};
464 
                                dat_o <= pc + 32'd2;
465 
                                vect <= rfoa;
466 
                                state <= JSR1;
467 
                                $stop;
468 
                        end
469 
                `JSL:
470 
                        begin
471 
                                radr <= isp_dec;
472 
                                wadr <= isp_dec;
473 
                                wdat <= pc + 32'd5;
474 
                                cyc_o <= 1'b1;
475 
                                stb_o <= 1'b1;
476 
                                we_o <= 1'b1;
477 
                                sel_o <= 4'hF;
478 
                                adr_o <= {isp_dec,2'b00};
479 
                                dat_o <= pc + 32'd5;
480 
                                vect <= ir[39:8];
481 
                                state <= JSR1;
482 
                        end
483 
                `BSR:
484 
                        begin
485 
                                radr <= isp_dec;
486 
                                wadr <= isp_dec;
487 
                                wdat <= pc + 32'd3;
488 
                                cyc_o <= 1'b1;
489 
                                stb_o <= 1'b1;
490 
                                we_o <= 1'b1;
491 
                                sel_o <= 4'hF;
492 
                                adr_o <= {isp_dec,2'b00};
493 
                                dat_o <= pc + 32'd3;
494 
                                vect <= pc + {{16{ir[23]}},ir[23:8]};
495 
                                state <= JSR1;
496 
                        end
497 
                `JSR_INDX:
498 
                        begin
499 
                                radr <= isp - 32'd1;
500 
                                wadr <= isp - 32'd1;
501 
                                wdat <= pc + 32'd5;
502 
                                cyc_o <= 1'b1;
503 
                                stb_o <= 1'b1;
504 
                                we_o <= 1'b1;
505 
                                sel_o <= 4'hF;
506 
                                adr_o <= {isp-32'd1,2'b00};
507 
                                dat_o <= pc + 32'd5;
508 
                                state <= JSR_INDX1;
509 
                        end
510 
//              `JSR16:
511 
//                      begin
512 
//                              radr <= isp - 32'd1;
513 
//                              wadr <= isp - 32'd1;
514 
//                              wdat <= pc + 32'd3;
515 
//                              cyc_o <= 1'b1;
516 
//                              stb_o <= 1'b1;
517 
//                              we_o <= 1'b1;
518 
//                              sel_o <= 4'hF;
519 
//                              adr_o <= {isp-32'd1,2'b00};
520 
//                              dat_o <= pc + 32'd3;
521 
//                              state <= JSR161;
522 
//                      end
523 
                `RTS,`RTL:
524 
                                begin
525 
                                radr <= isp;
526 21 robfinch 
                                load_what <= `PC_310;
527 
                                state <= LOAD_MAC1;
528 20 robfinch 
                                end
529 
                `RTI:   begin
530 
                                radr <= isp;
531 21 robfinch 
                                load_what <= `SR_310;
532 
                                state <= LOAD_MAC1;
533 20 robfinch 
                                end
534 
                `BEQ,`BNE,`BPL,`BMI,`BCC,`BCS,`BVC,`BVS,`BRA:
535 
                        begin
536 
                                state <= IFETCH;
537 
                                if (ir[15:8]==8'h00) begin
538 
                                        radr <= isp_dec;
539 
                                        wadr <= isp_dec;
540 
                                        wdat <= pc + 32'd2;
541 
                                        cyc_o <= 1'b1;
542 
                                        stb_o <= 1'b1;
543 
                                        we_o <= 1'b1;
544 
                                        sel_o <= 4'hF;
545 
                                        adr_o <= {isp_dec,2'b00};
546 
                                        dat_o <= pc + 32'd2;
547 
                                        vect <= {vbr[31:9],`SLP_VECTNO,2'b00};
548 
                                        state <= IRQ1;
549 
                                end
550 
                                else if (ir[15:8]==8'h1) begin
551 
                                        if (takb)
552 
                                                pc <= pc + {{16{ir[31]}},ir[31:16]};
553 
                                        else
554 
                                                pc <= pc + 32'd4;
555 
                                end
556 
                                else begin
557 
                                        if (takb)
558 
                                                pc <= pc + {{24{ir[15]}},ir[15:8]};
559 
                                        else
560 
                                                pc <= pc + 32'd2;
561 
                                end
562 
                        end
563 
/*              `BEQ_RR:
564 
                        begin
565 
                                state <= IFETCH;
566 
                                if (ir[23:16]==8'h00) begin
567 
                                        radr <= isp_dec;
568 
                                        wadr <= isp_dec;
569 
                                        wdat <= pc + 32'd2;
570 
                                        cyc_o <= 1'b1;
571 
                                        stb_o <= 1'b1;
572 
                                        we_o <= 1'b1;
573 
                                        sel_o <= 4'hF;
574 
                                        adr_o <= {isp_dec,2'b00};
575 
                                        dat_o <= pc + 32'd2;
576 
                                        vect <= `SLP_VECT;
577 
                                        state <= IRQ1;
578 
                                end
579 
                                else if (ir[23:16]==8'h1) begin
580 
                                        if (rfoa==rfob)
581 
                                                pc <= pc + {{16{ir[39]}},ir[39:24]};
582 
                                        else
583 
                                                pc <= pc + 32'd5;
584 
                                end
585 
                                else begin
586 
                                        if (takb)
587 
                                                pc <= pc + {{24{ir[23]}},ir[23:16]};
588 
                                        else
589 
                                                pc <= pc + 32'd3;
590 
                                end
591 
                        end*/
592 
                `BRL:
593 
                        begin
594 
                                if (ir[23:8]==16'h0000) begin
595 
                                        radr <= isp_dec;
596 
                                        wadr <= isp_dec;
597 
                                        wdat <= pc + 32'd3;
598 
                                        cyc_o <= 1'b1;
599 
                                        stb_o <= 1'b1;
600 
                                        we_o <= 1'b1;
601 
                                        sel_o <= 4'hF;
602 
                                        adr_o <= {isp_dec,2'b00};
603 
                                        dat_o <= pc + 32'd3;
604 
                                        vect <= {vbr[31:9],`SLP_VECTNO,2'b00};
605 
                                        state <= IRQ1;
606 
                                end
607 
                                else begin
608 
                                        pc <= pc + {{16{ir[23]}},ir[23:8]};
609 
                                        state <= IFETCH;
610 
                                end
611 
                        end
612 
                `PHP:
613 
                        begin
614 
                                cyc_o <= 1'b1;
615 
                                stb_o <= 1'b1;
616 
                                sel_o <= 4'hF;
617 
                                we_o <= 1'b1;
618 
                                radr <= isp_dec;
619 
                                wadr <= isp_dec;
620 
                                wdat <= sr;
621 
                                adr_o <= {isp_dec,2'b00};
622 
                                dat_o <= sr;
623 
                                isp <= isp_dec;
624 
                                state <= PHP1;
625 
                        end
626 
                `PHA:
627 
                        begin
628 
                                cyc_o <= 1'b1;
629 
                                stb_o <= 1'b1;
630 
                                sel_o <= 4'hF;
631 
                                we_o <= 1'b1;
632 
                                radr <= isp_dec;
633 
                                wadr <= isp_dec;
634 
                                wdat <= acc;
635 
                                adr_o <= {isp_dec,2'b00};
636 
                                dat_o <= acc;
637 
                                isp <= isp_dec;
638 
                                state <= PHP1;
639 
                        end
640 
                `PHX:
641 
                        begin
642 
                                cyc_o <= 1'b1;
643 
                                stb_o <= 1'b1;
644 
                                sel_o <= 4'hF;
645 
                                we_o <= 1'b1;
646 
                                radr <= isp_dec;
647 
                                wadr <= isp_dec;
648 
                                wdat <= x;
649 
                                adr_o <= {isp_dec,2'b00};
650 
                                dat_o <= x;
651 
                                isp <= isp_dec;
652 
                                state <= PHP1;
653 
                        end
654 
                `PHY:
655 
                        begin
656 
                                cyc_o <= 1'b1;
657 
                                stb_o <= 1'b1;
658 
                                sel_o <= 4'hF;
659 
                                we_o <= 1'b1;
660 
                                radr <= isp_dec;
661 
                                wadr <= isp_dec;
662 
                                wdat <= y;
663 
                                adr_o <= {isp_dec,2'b00};
664 
                                dat_o <= y;
665 
                                isp <= isp_dec;
666 
                                state <= PHP1;
667 
                        end
668 
                `PUSH:
669 
                        begin
670 
                                cyc_o <= 1'b1;
671 
                                stb_o <= 1'b1;
672 
                                sel_o <= 4'hF;
673 
                                we_o <= 1'b1;
674 
                                radr <= isp_dec;
675 
                                wadr <= isp_dec;
676 
                                wdat <= rfoa;
677 
                                adr_o <= {isp_dec,2'b00};
678 
                                dat_o <= rfoa;
679 
                                state <= PHP1;
680 
                                isp <= isp_dec;
681 
                                pc <= pc + 32'd1;
682 
                        end
683 
                `PLP:
684 
                        begin
685 
                                radr <= isp;
686 
                                pc <= pc + 32'd1;
687 21 robfinch 
                                load_what <= `SR_310;
688 
                                state <= LOAD_MAC1;
689 20 robfinch 
                        end
690 
                `PLA,`PLX,`PLY:
691 
                        begin
692 
                                radr <= isp;
693 
                                isp <= isp_inc;
694 21 robfinch 
                                load_what <= `WORD_311;
695 
                                state <= LOAD_MAC1;
696 20 robfinch 
                                pc <= pc + 32'd1;
697 
                        end
698 
                `POP:
699 
                        begin
700 
                                Rt <= ir[15:12];
701 
                                radr <= isp;
702 
                                isp <= isp_inc;
703 21 robfinch 
                                load_what <= `WORD_311;
704 
                                state <= LOAD_MAC1;
705 20 robfinch 
                                pc <= pc + 32'd2;
706 
                        end
707 
                default:        // unimplemented opcode
708 21 robfinch 
                        begin
709 
                                radr <= isp_dec;
710 
                                wadr <= isp_dec;
711 
                                wdat <= pc + 32'd1;
712 
                                cyc_o <= 1'b1;
713 
                                stb_o <= 1'b1;
714 
                                we_o <= 1'b1;
715 
                                sel_o <= 4'hF;
716 
                                adr_o <= {isp_dec,2'b00};
717 
                                dat_o <= pc + 32'd1;
718 
                                vect <= {vbr[31:9],9'd495,2'b00};
719 
                                state <= IRQ1;
720 
                        end
721 20 robfinch 
                endcase
722 
        end

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