Memory.v

   1 `include "ARM_Constants.v"
   2
   3 module Memory(
   4         input clk,
   5         input Nrst,
   6
   7         input flush,
   8
   9         /* bus interface */
  10         output reg [31:0] busaddr,
  11         output reg rd_req,
  12         output reg wr_req,
  13         input rw_wait,
  14         output reg [31:0] wr_data,
  15         input [31:0] rd_data,
  16         output reg [2:0] data_size,
  17
  18         /* regfile interface */
  19         output reg [3:0] st_read,
  20         input [31:0] st_data,
  21
  22         /* Coprocessor interface */
  23         output reg cp_req,
  24         input cp_ack,
  25         input cp_busy,
  26         output reg cp_rnw,      /* 1 = read from CP, 0 = write to CP */
  27         input [31:0] cp_read,
  28         output reg [31:0] cp_write,
  29
  30         /* stage inputs */
  31         input inbubble,
  32         input [31:0] pc,
  33         input [31:0] insn,
  34         input [31:0] op0,
  35         input [31:0] op1,
  36         input [31:0] op2,
  37         input [31:0] spsr,
  38         input [31:0] cpsr,
  39         input cpsrup,
  40         input write_reg,
  41         input [3:0] write_num,
  42         input [31:0] write_data,
  43
  44         /* outputs */
  45         output reg outstall,
  46         output reg outbubble,
  47         output reg [31:0] outpc,
  48         output reg [31:0] outinsn,
  49         output reg out_write_reg = 1'b0,
  50         output reg [3:0] out_write_num = 4'bxxxx,
  51         output reg [31:0] out_write_data = 32'hxxxxxxxx,
  52         output reg [31:0] outspsr = 32'hxxxxxxxx,
  53         output reg [31:0] outcpsr = 32'hxxxxxxxx,
  54         output reg outcpsrup = 1'hx
  55         );
  56
  57         reg [31:0] addr, raddr, prev_raddr, next_regdata, next_outcpsr;
  58         reg next_outcpsrup;
  59         reg [31:0] prevaddr;
  60         reg [3:0] next_regsel, cur_reg, prev_reg;
  61         reg next_writeback;
  62
  63         reg next_outbubble;
  64         reg next_write_reg;
  65         reg [3:0] next_write_num;
  66         reg [31:0] next_write_data;
  67
  68         reg [3:0] lsr_state = 4'b0001, next_lsr_state;
  69         reg [31:0] align_s1, align_s2, align_rddata;
  70
  71         reg [2:0] lsrh_state = 3'b001, next_lsrh_state;
  72         reg [31:0] lsrh_rddata;
  73         reg [15:0] lsrh_rddata_s1;
  74         reg [7:0] lsrh_rddata_s2;
  75
  76         reg [15:0] regs, next_regs;
  77         reg [3:0] lsm_state = 4'b0001, next_lsm_state;
  78         reg [5:0] offset, prev_offset, offset_sel;
  79
  80         reg [31:0] swp_oldval, next_swp_oldval;
  81         reg [1:0] swp_state = 2'b01, next_swp_state;
  82
  83         reg do_rd_data_latch;
  84         reg [31:0] rd_data_latch = 32'hxxxxxxxx;
  85
  86         always @(posedge clk)
  87         begin
  88                 outpc <= pc;
  89                 outinsn <= insn;
  90                 outbubble <= next_outbubble;
  91                 out_write_reg <= next_write_reg;
  92                 out_write_num <= next_write_num;
  93                 out_write_data <= next_write_data;
  94                 regs <= next_regs;
  95                 prev_reg <= cur_reg;
  96                 if (!rw_wait)
  97                         prev_offset <= offset;
  98                 prev_raddr <= raddr;
  99                 outcpsr <= next_outcpsr;
 100                 outspsr <= spsr;
 101                 outcpsrup <= next_outcpsrup;
 102                 swp_state <= next_swp_state;
 103                 lsm_state <= next_lsm_state;
 104                 lsr_state <= next_lsr_state;
 105                 lsrh_state <= next_lsrh_state;
 106                 if (do_rd_data_latch)
 107                         rd_data_latch <= rd_data;
 108                 prevaddr <= addr;
 109         end
 110
 111         reg delayedflush = 0;
 112         always @(posedge clk)
 113                 if (flush && outstall /* halp! I can't do it now, maybe later? */)
 114                         delayedflush <= 1;
 115                 else if (!outstall /* anything has been handled this time around */)
 116                         delayedflush <= 0;
 117
 118         always @(*)
 119         begin
 120                 addr = prevaddr;
 121                 raddr = 32'hxxxxxxxx;
 122                 rd_req = 1'b0;
 123                 wr_req = 1'b0;
 124                 wr_data = 32'hxxxxxxxx;
 125                 busaddr = 32'hxxxxxxxx;
 126                 data_size = 3'bxxx;
 127                 outstall = 1'b0;
 128                 do_rd_data_latch = 0;
 129                 next_write_reg = write_reg;
 130                 next_write_num = write_num;
 131                 next_write_data = write_data;
 132                 next_outbubble = inbubble;
 133                 next_regs = regs;
 134                 cp_req = 1'b0;
 135                 cp_rnw = 1'bx;
 136                 cp_write = 32'hxxxxxxxx;
 137                 offset = prev_offset;
 138                 next_outcpsr = lsm_state == 4'b0010 ? outcpsr : cpsr;
 139                 next_outcpsrup = cpsrup;
 140                 lsrh_rddata = 32'hxxxxxxxx;
 141                 lsrh_rddata_s1 = 16'hxxxx;
 142                 lsrh_rddata_s2 = 8'hxx;
 143                 next_lsm_state = lsm_state;
 144                 next_lsr_state = lsr_state;
 145                 next_lsrh_state = lsrh_state;
 146                 next_swp_oldval = swp_oldval;
 147                 next_swp_state = swp_state;
 148                 cur_reg = prev_reg;
 149
 150                 /* XXX shit not given about endianness */
 151                 casez(insn)
 152                 `DECODE_ALU_SWP: if(!inbubble) begin
 153                         outstall = rw_wait;
 154                         next_outbubble = rw_wait;
 155                         busaddr = {op0[31:2], 2'b0};
 156                         data_size = insn[22] ? 3'b001 : 3'b100;
 157                         case(swp_state)
 158                         2'b01: begin
 159                                 rd_req = 1'b1;
 160                                 outstall = 1'b1;
 161                                 if(!rw_wait) begin
 162                                         next_swp_state = 2'b10;
 163                                         next_swp_oldval = rd_data;
 164                                 end
 165                                 $display("SWP: read stage");
 166                         end
 167                         2'b10: begin
 168                                 wr_req = 1'b1;
 169                                 wr_data = insn[22] ? {4{op1[7:0]}} : op1;
 170                                 next_write_reg = 1'b1;
 171                                 next_write_num = insn[15:12];
 172                                 next_write_data = insn[22] ? {24'b0, swp_oldval[7:0]} : swp_oldval;
 173                                 if(!rw_wait)
 174                                         next_swp_state = 2'b01;
 175                                 $display("SWP: write stage");
 176                         end
 177                         default: begin end
 178                         endcase
 179                 end
 180                 `DECODE_ALU_MULT: begin end
 181                 `DECODE_ALU_HDATA_REG,
 182                 `DECODE_ALU_HDATA_IMM: if(!inbubble) begin
 183                         next_outbubble = rw_wait;
 184                         outstall = rw_wait;
 185                         addr = insn[23] ? op0 + op1 : op0 - op1; /* up/down select */
 186                         raddr = insn[24] ? op0 : addr; /* pre/post increment */
 187                         busaddr = raddr;
 188                         /* rotate to correct position */
 189                         case(insn[6:5])
 190                         2'b00: begin end /* swp */
 191                         2'b01: begin /* unsigned half */
 192                                 wr_data = {2{op2[15:0]}}; /* XXX need to store halfword */
 193                                 data_size = 3'b010;
 194                                 lsrh_rddata = {16'b0, raddr[1] ? rd_data[31:16] : rd_data[15:0]};
 195                         end
 196                         2'b10: begin /* signed byte */
 197                                 wr_data = {4{op2[7:0]}};
 198                                 data_size = 3'b001;
 199                                 lsrh_rddata_s1 = raddr[1] ? rd_data[31:16] : rd_data[15:0];
 200                                 lsrh_rddata_s2 = raddr[0] ? lsrh_rddata_s1[15:8] : lsrh_rddata_s1[7:0];
 201                                 lsrh_rddata = {{24{lsrh_rddata_s2[7]}}, lsrh_rddata_s2};
 202                         end
 203                         2'b11: begin /* signed half */
 204                                 wr_data = {2{op2[15:0]}};
 205                                 data_size = 3'b010;
 206                                 lsrh_rddata = raddr[1] ? {{16{rd_data[31]}}, rd_data[31:16]} : {{16{rd_data[15]}}, rd_data[15:0]};
 207                         end
 208                         endcase
 209
 210                         case(lsrh_state)
 211                         3'b001: begin
 212                                 rd_req = insn[20];
 213                                 wr_req = ~insn[20];
 214                                 next_write_num = insn[15:12];
 215                                 next_write_data = lsrh_rddata;
 216                                 if(insn[20]) begin
 217                                         next_write_reg = 1'b1;
 218                                 end
 219                                 if(insn[21] | !insn[24]) begin
 220                                         outstall = 1'b1;
 221                                         if(!rw_wait)
 222                                                 next_lsrh_state = 3'b010;
 223                                 end
 224                                 $display("ALU_LDRSTRH: rd_req %d, wr_req %d", rd_req, wr_req);
 225                         end
 226                         3'b010: begin
 227                                 next_outbubble = 1'b0;
 228                                 next_write_reg = 1'b1;
 229                                 next_write_num = insn[19:16];
 230                                 next_write_data = addr;
 231                                 next_lsrh_state = 3'b100;
 232                         end
 233                         3'b100: begin
 234                                 outstall = 0;
 235                                 next_lsrh_state = 3'b001;
 236                         end
 237                         default: begin end
 238                         endcase
 239
 240                         if ((lsrh_state == 3'b001) && flush) begin      /* Reject it. */
 241                                 outstall = 1'b0;
 242                                 next_lsrh_state = 3'b001;
 243                         end
 244                 end
 245                 `DECODE_LDRSTR_UNDEFINED: begin end
 246                 `DECODE_LDRSTR: if(!inbubble) begin
 247                         next_outbubble = rw_wait;
 248                         outstall = rw_wait;
 249                         addr = insn[23] ? op0 + op1 : op0 - op1; /* up/down select */
 250                         raddr = insn[24] ? addr : op0; /* pre/post increment */
 251                         busaddr = raddr;
 252                         /* rotate to correct position */
 253                         align_s1 = raddr[1] ? {rd_data[15:0], rd_data[31:16]} : rd_data;
 254                         align_s2 = raddr[0] ? {align_s1[7:0], align_s1[31:8]} : align_s1;
 255                         /* select byte or word */
 256                         align_rddata = insn[22] ? {24'b0, align_s2[7:0]} : align_s2;
 257                         wr_data = insn[22] ? {24'h0, {op2[7:0]}} : op2;
 258                         data_size = insn[22] ? 3'b001 : 3'b100;
 259                         case(lsr_state)
 260                         4'b0001: begin
 261                                 rd_req = insn[20] /* L */ || insn[22] /* B */;
 262                                 wr_req = !insn[20] /* L */ && !insn[22]/* B */;
 263                                 next_write_reg = insn[20] /* L */;
 264                                 next_write_num = insn[15:12];
 265                                 if(insn[20] /* L */) begin
 266                                         next_write_data = insn[22] /* B */ ? {24'h0, align_rddata[7:0]} : align_rddata;
 267                                 end
 268                                 if (insn[22] /* B */ && !insn[20] /* L */) begin
 269                                         do_rd_data_latch = 1;
 270                                         outstall = 1'b1;
 271                                         if (!rw_wait)
 272                                                 next_lsr_state = 4'b0010;       /* XXX: One-hot, my ass. */
 273                                 end else if(insn[21] /* W */ | !insn[24] /* P */) begin
 274                                         outstall = 1'b1;
 275                                         if(!rw_wait)
 276                                                 next_lsr_state = 4'b0100;
 277                                 end
 278                                 $display("LDRSTR: rd_req %d, wr_req %d, raddr %08x, wait %d", rd_req, wr_req, raddr, rw_wait);
 279                         end
 280                         4'b0010: begin
 281                                 $display("LDRSTR: Handling STRB");
 282                                 outstall = 1;
 283                                 rd_req = 0;
 284                                 wr_req = 1;
 285                                 next_write_reg = 0;
 286                                 case (busaddr[1:0])
 287                                 2'b00: wr_data = {rd_data_latch[31:8], op2[7:0]};
 288                                 2'b01: wr_data = {rd_data_latch[31:16], op2[7:0], rd_data_latch[7:0]};
 289                                 2'b10: wr_data = {rd_data_latch[31:24], op2[7:0], rd_data_latch[15:0]};
 290                                 2'b11: wr_data = {op2[7:0], rd_data_latch[23:0]};
 291                                 endcase
 292                                 if(insn[21] /* W */ | !insn[24] /* P */) begin
 293                                         if(!rw_wait)
 294                                                 next_lsr_state = 4'b0100;
 295                                 end else if (!rw_wait)
 296                                         next_lsr_state = 4'b1000;
 297                         end
 298                         4'b0100: begin
 299                                 outstall = 1;
 300                                 rd_req = 0;
 301                                 wr_req= 0;
 302                                 next_outbubble = 0;
 303                                 next_write_reg = 1'b1;
 304                                 next_write_num = insn[19:16];
 305                                 next_write_data = addr;
 306                                 next_lsr_state = 4'b1000;
 307                         end
 308                         4'b1000: begin
 309                                 rd_req = 0;
 310                                 wr_req= 0;
 311                                 outstall = 0;
 312                                 next_lsr_state = 4'b0001;
 313                         end
 314                         default: begin end
 315                         endcase
 316
 317                         if ((lsr_state == 4'b0001) && flush) begin      /* Reject it. */
 318                                 outstall = 1'b0;
 319                                 next_lsr_state = 4'b0001;
 320                         end
 321                 end
 322                 /* XXX ldm/stm incorrect in that stupid case where one of the listed regs is the base reg */
 323                 `DECODE_LDMSTM: if(!inbubble) begin
 324                         outstall = rw_wait;
 325                         next_outbubble = rw_wait;
 326                         data_size = 3'b100;
 327                         case(lsm_state)
 328                         4'b0001: begin
 329 //                              next_regs = insn[23] ? op1[15:0] : op1[0:15];
 330                                 /** verilator can suck my dick */
 331                                 $display("LDMSTM: Round 1: base register: %08x, reg list %b", op0, op1[15:0]);
 332                                 next_regs = insn[23] /* U */ ? op1[15:0] : {op1[0], op1[1], op1[2], op1[3], op1[4], op1[5], op1[6], op1[7],
 333                                                                             op1[8], op1[9], op1[10], op1[11], op1[12], op1[13], op1[14], op1[15]};
 334                                 offset = 6'b0;
 335                                 outstall = 1'b1;
 336                                 next_lsm_state = 4'b0010;
 337                         end
 338                         4'b0010: begin
 339                                 rd_req = insn[20];
 340                                 wr_req = ~insn[20];
 341                                 casez(regs)
 342                                 16'b???????????????1: begin
 343                                         cur_reg = 4'h0;
 344                                         next_regs = {regs[15:1], 1'b0};
 345                                 end
 346                                 16'b??????????????10: begin
 347                                         cur_reg = 4'h1;
 348                                         next_regs = {regs[15:2], 2'b0};
 349                                 end
 350                                 16'b?????????????100: begin
 351                                         cur_reg = 4'h2;
 352                                         next_regs = {regs[15:3], 3'b0};
 353                                 end
 354                                 16'b????????????1000: begin
 355                                         cur_reg = 4'h3;
 356                                         next_regs = {regs[15:4], 4'b0};
 357                                 end
 358                                 16'b???????????10000: begin
 359                                         cur_reg = 4'h4;
 360                                         next_regs = {regs[15:5], 5'b0};
 361                                 end
 362                                 16'b??????????100000: begin
 363                                         cur_reg = 4'h5;
 364                                         next_regs = {regs[15:6], 6'b0};
 365                                 end
 366                                 16'b?????????1000000: begin
 367                                         cur_reg = 4'h6;
 368                                         next_regs = {regs[15:7], 7'b0};
 369                                 end
 370                                 16'b????????10000000: begin
 371                                         cur_reg = 4'h7;
 372                                         next_regs = {regs[15:8], 8'b0};
 373                                 end
 374                                 16'b???????100000000: begin
 375                                         cur_reg = 4'h8;
 376                                         next_regs = {regs[15:9], 9'b0};
 377                                 end
 378                                 16'b??????1000000000: begin
 379                                         cur_reg = 4'h9;
 380                                         next_regs = {regs[15:10], 10'b0};
 381                                 end
 382                                 16'b?????10000000000: begin
 383                                         cur_reg = 4'hA;
 384                                         next_regs = {regs[15:11], 11'b0};
 385                                 end
 386                                 16'b????100000000000: begin
 387                                         cur_reg = 4'hB;
 388                                         next_regs = {regs[15:12], 12'b0};
 389                                 end
 390                                 16'b???1000000000000: begin
 391                                         cur_reg = 4'hC;
 392                                         next_regs = {regs[15:13], 13'b0};
 393                                 end
 394                                 16'b??10000000000000: begin
 395                                         cur_reg = 4'hD;
 396                                         next_regs = {regs[15:14], 14'b0};
 397                                 end
 398                                 16'b?100000000000000: begin
 399                                         cur_reg = 4'hE;
 400                                         next_regs = {regs[15], 15'b0};
 401                                 end
 402                                 16'b1000000000000000: begin
 403                                         cur_reg = 4'hF;
 404                                         next_regs = 16'b0;
 405                                 end
 406                                 default: begin
 407                                         cur_reg = 4'hx;
 408                                         next_regs = 16'b0;
 409                                 end
 410                                 endcase
 411                                 cur_reg = insn[23] ? cur_reg : 4'hF - cur_reg;
 412                                 if(cur_reg == 4'hF && insn[22]) begin
 413                                         next_outcpsr = spsr;
 414                                         next_outcpsrup = 1;
 415                                 end
 416
 417                                 offset = prev_offset + 6'h4;
 418                                 offset_sel = insn[24] ? offset : prev_offset;
 419                                 raddr = insn[23] ? op0 + {26'b0, offset_sel} : op0 - {26'b0, offset_sel};
 420                                 if(insn[20]) begin
 421                                         next_write_reg = !rw_wait;
 422                                         next_write_num = cur_reg;
 423                                         next_write_data = rd_data;
 424                                 end
 425                                 if (rw_wait) begin
 426                                         next_regs = regs;
 427                                         cur_reg = prev_reg;     /* whoops, do this one again */
 428                                 end
 429
 430                                 st_read = cur_reg;
 431                                 wr_data = (cur_reg == 4'hF) ? (pc + 12) : st_data;
 432                                 busaddr = raddr;
 433
 434                                 $display("LDMSTM: Stage 2: Writing: regs %b, next_regs %b, reg %d, wr_data %08x, addr %08x", regs, next_regs, cur_reg, wr_data, busaddr);
 435
 436                                 outstall = 1'b1;
 437
 438                                 if(next_regs == 16'b0) begin
 439                                         next_lsm_state = 4'b0100;
 440                                 end
 441                         end
 442                         4'b0100: begin
 443                                 outstall = 1;
 444                                 next_outbubble = 0;
 445                                 next_write_reg = insn[21] /* writeback */;
 446                                 next_write_num = insn[19:16];
 447                                 next_write_data = insn[23] ? op0 + {26'b0, prev_offset} : op0 - {26'b0, prev_offset};
 448                                 next_lsm_state = 4'b1000;
 449                                 $display("LDMSTM: Stage 3: Writing back");
 450                         end
 451                         4'b1000: begin
 452                                 outstall = 0;
 453                                 next_lsm_state = 4'b0001;
 454                         end
 455                         default: $stop;
 456                         endcase
 457                         if ((lsm_state == 4'b0001) && flush) begin      /* Reject it. */
 458                                 outstall = 1'b0;
 459                                 next_lsm_state = 4'b0001;
 460                         end
 461                         $display("LDMSTM: Decoded, bubble %d, insn %08x, lsm state %b -> %b, stall %d", inbubble, insn, lsm_state, next_lsm_state, outstall);
 462                 end
 463                 `DECODE_LDCSTC: if(!inbubble) begin
 464                         $display("WARNING: Unimplemented LDCSTC");
 465                 end
 466                 `DECODE_CDP: if(!inbubble) begin
 467                         cp_req = 1;
 468                         if (cp_busy) begin
 469                                 outstall = 1;
 470                                 next_outbubble = 1;
 471                         end
 472                         if (!cp_ack) begin
 473                                 /* XXX undefined instruction trap */
 474                                 $display("WARNING: Possible CDP undefined instruction");
 475                         end
 476                 end
 477                 `DECODE_MRCMCR: if(!inbubble) begin
 478                         cp_req = 1;
 479                         cp_rnw = insn[20] /* L */;
 480                         if (insn[20] == 0 /* store to coprocessor */)
 481                                 cp_write = op0;
 482                         else begin
 483                                 if (insn[15:12] != 4'hF /* Fuck you ARM */) begin
 484                                         next_write_reg = 1'b1;
 485                                         next_write_num = insn[15:12];
 486                                         next_write_data = cp_read;
 487                                 end else begin
 488                                         next_outcpsr = {cp_read[31:28], cpsr[27:0]};
 489                                         next_outcpsrup = 1;
 490                                 end
 491                         end
 492                         if (cp_busy) begin
 493                                 outstall = 1;
 494                                 next_outbubble = 1;
 495                         end
 496                         if (!cp_ack) begin
 497                                 $display("WARNING: Possible MRCMCR undefined instruction: cp_ack %d, cp_busy %d",cp_ack, cp_busy);
 498                         end
 499                         $display("MRCMCR: ack %d, busy %d", cp_ack, cp_busy);
 500                 end
 501                 default: begin end
 502                 endcase
 503
 504                 if ((flush || delayedflush) && !outstall)
 505                         next_outbubble = 1'b1;
 506         end
 507 endmodule