Memory.v

   1 `include "ARM_Constants.v"
   2
   3 `define SWP_READING     2'b01
   4 `define SWP_WRITING     2'b10
   5
   6 `define LSRH_MEMIO      3'b001
   7 `define LSRH_BASEWB     3'b010
   8 `define LSRH_WBFLUSH    3'b100
   9
  10 `define LSR_MEMIO       4'b0001
  11 `define LSR_STRB_WR     4'b0010
  12 `define LSR_BASEWB      4'b0100
  13 `define LSR_WBFLUSH     4'b1000
  14
  15 `define LSM_SETUP       4'b0001
  16 `define LSM_MEMIO       4'b0010
  17 `define LSM_BASEWB      4'b0100
  18 `define LSM_WBFLUSH     4'b1000
  19
  20
  21 module Memory(
  22         input clk,
  23         input Nrst,
  24
  25         input flush,
  26
  27         /* bus interface */
  28         output reg [31:0] busaddr,
  29         output reg rd_req,
  30         output reg wr_req,
  31         input rw_wait,
  32         output reg [31:0] wr_data,
  33         input [31:0] rd_data,
  34         output reg [2:0] data_size,
  35
  36         /* regfile interface */
  37         output reg [3:0] st_read,
  38         input [31:0] st_data,
  39
  40         /* Coprocessor interface */
  41         output reg cp_req,
  42         input cp_ack,
  43         input cp_busy,
  44         output reg cp_rnw,      /* 1 = read from CP, 0 = write to CP */
  45         input [31:0] cp_read,
  46         output reg [31:0] cp_write,
  47
  48         /* stage inputs */
  49         input inbubble,
  50         input [31:0] pc,
  51         input [31:0] insn,
  52         input [31:0] op0,
  53         input [31:0] op1,
  54         input [31:0] op2,
  55         input [31:0] spsr,
  56         input [31:0] cpsr,
  57         input cpsrup,
  58         input write_reg,
  59         input [3:0] write_num,
  60         input [31:0] write_data,
  61
  62         /* outputs */
  63         output reg outstall,
  64         output reg outbubble,
  65         output reg [31:0] outpc,
  66         output reg [31:0] outinsn,
  67         output reg out_write_reg = 1'b0,
  68         output reg [3:0] out_write_num = 4'bxxxx,
  69         output reg [31:0] out_write_data = 32'hxxxxxxxx,
  70         output reg [31:0] outspsr = 32'hxxxxxxxx,
  71         output reg [31:0] outcpsr = 32'hxxxxxxxx,
  72         output reg outcpsrup = 1'hx
  73         );
  74
  75         reg [31:0] addr, raddr, prev_raddr, next_regdata, next_outcpsr;
  76         reg next_outcpsrup;
  77         reg [31:0] prevaddr;
  78         reg [3:0] next_regsel, cur_reg, prev_reg;
  79         reg next_writeback;
  80
  81         reg next_outbubble;
  82         reg next_write_reg;
  83         reg [3:0] next_write_num;
  84         reg [31:0] next_write_data;
  85
  86         reg [3:0] lsr_state = 4'b0001, next_lsr_state;
  87         reg [31:0] align_s1, align_s2, align_rddata;
  88
  89         reg [2:0] lsrh_state = 3'b001, next_lsrh_state;
  90         reg [31:0] lsrh_rddata;
  91         reg [15:0] lsrh_rddata_s1;
  92         reg [7:0] lsrh_rddata_s2;
  93
  94         reg [15:0] regs, next_regs;
  95         reg [3:0] lsm_state = 4'b0001, next_lsm_state;
  96         reg [5:0] offset, prev_offset, offset_sel;
  97
  98         reg [31:0] swp_oldval, next_swp_oldval;
  99         reg [1:0] swp_state = 2'b01, next_swp_state;
 100
 101         reg do_rd_data_latch;
 102         reg [31:0] rd_data_latch = 32'hxxxxxxxx;
 103
 104         always @(posedge clk)
 105         begin
 106                 outpc <= pc;
 107                 outinsn <= insn;
 108                 outbubble <= next_outbubble;
 109                 out_write_reg <= next_write_reg;
 110                 out_write_num <= next_write_num;
 111                 out_write_data <= next_write_data;
 112                 regs <= next_regs;
 113                 prev_reg <= cur_reg;
 114                 if (!rw_wait)
 115                         prev_offset <= offset;
 116                 prev_raddr <= raddr;
 117                 outcpsr <= next_outcpsr;
 118                 outspsr <= spsr;
 119                 outcpsrup <= next_outcpsrup;
 120                 swp_state <= next_swp_state;
 121                 lsm_state <= next_lsm_state;
 122                 lsr_state <= next_lsr_state;
 123                 lsrh_state <= next_lsrh_state;
 124                 if (do_rd_data_latch)
 125                         rd_data_latch <= rd_data;
 126                 prevaddr <= addr;
 127         end
 128
 129         reg delayedflush = 0;
 130         always @(posedge clk)
 131                 if (flush && outstall /* halp! I can't do it now, maybe later? */)
 132                         delayedflush <= 1;
 133                 else if (!outstall /* anything has been handled this time around */)
 134                         delayedflush <= 0;
 135
 136         /* Drive the state machines and stall. */
 137         always @(*)
 138         begin
 139                 outstall = 1'b0;
 140                 next_lsm_state = lsm_state;
 141                 next_lsr_state = lsr_state;
 142                 next_lsrh_state = lsrh_state;
 143                 next_swp_state = swp_state;
 144                 casez(insn)
 145                 `DECODE_ALU_SWP: if(!inbubble) begin
 146                         case(swp_state)
 147                         `SWP_READING: begin
 148                                 outstall = 1'b1;
 149                                 if (!rw_wait)
 150                                         next_swp_state = `SWP_WRITING;
 151                                 $display("SWP: read stage");
 152                         end
 153                         `SWP_WRITING: begin
 154                                 outstall = rw_wait;
 155                                 if(!rw_wait)
 156                                         next_swp_state = `SWP_READING;
 157                                 $display("SWP: write stage");
 158                         end
 159                         default: begin
 160                                 outstall = 1'bx;
 161                                 next_swp_state = 2'bxx;
 162                         end
 163                         endcase
 164                 end
 165                 `DECODE_ALU_MULT: begin end
 166                 `DECODE_ALU_HDATA_REG,
 167                 `DECODE_ALU_HDATA_IMM: if(!inbubble) begin
 168                         case(lsrh_state)
 169                         `LSRH_MEMIO: begin
 170                                 outstall = rw_wait;
 171                                 if(insn[21] | !insn[24]) begin
 172                                         outstall = 1'b1;
 173                                         if(!rw_wait)
 174                                                 next_lsrh_state = `LSRH_BASEWB;
 175                                 end
 176
 177                                 if (flush) /* special case! */ begin
 178                                         outstall = 1'b0;
 179                                         next_lsrh_state = `LSRH_MEMIO;
 180                                 end
 181
 182                                 $display("ALU_LDRSTRH: rd_req %d, wr_req %d", rd_req, wr_req);
 183                         end
 184                         `LSRH_BASEWB: begin
 185                                 outstall = 1'b1;
 186                                 next_lsrh_state = `LSRH_WBFLUSH;
 187                         end
 188                         `LSRH_WBFLUSH: begin
 189                                 outstall = 1'b0;
 190                                 next_lsrh_state = `LSRH_MEMIO;
 191                         end
 192                         default: begin
 193                                 outstall = 1'bx;
 194                                 next_lsrh_state = 3'bxxx;
 195                         end
 196                         endcase
 197                 end
 198                 `DECODE_LDRSTR_UNDEFINED: begin end
 199                 `DECODE_LDRSTR: if(!inbubble) begin
 200                         outstall = rw_wait;
 201                         case(lsr_state)
 202                         `LSR_MEMIO: begin
 203                                 outstall = rw_wait;
 204                                 next_lsr_state = `LSR_MEMIO;
 205                                 if (insn[22] /* B */ && !insn[20] /* L */) begin        /* i.e., strb */
 206                                         outstall = 1'b1;
 207                                         if (!rw_wait)
 208                                                 next_lsr_state = `LSR_STRB_WR;
 209                                 end else if (insn[21] /* W */ || !insn[24] /* P */) begin       /* writeback needed */
 210                                         outstall = 1'b1;
 211                                         if (!rw_wait)
 212                                                 next_lsr_state = `LSR_BASEWB;
 213                                 end
 214
 215                                 if (flush) begin
 216                                         outstall = 1'b0;
 217                                         next_lsr_state = `LSR_MEMIO;
 218                                 end
 219                                 $display("LDRSTR: rd_req %d, wr_req %d, raddr %08x, wait %d", rd_req, wr_req, raddr, rw_wait);
 220                         end
 221                         `LSR_STRB_WR: begin
 222                                 outstall = 1;
 223                                 if(insn[21] /* W */ | !insn[24] /* P */) begin
 224                                         if(!rw_wait)
 225                                                 next_lsr_state = `LSR_BASEWB;
 226                                 end else if (!rw_wait)
 227                                         next_lsr_state = `LSR_WBFLUSH;
 228                                 $display("LDRSTR: Handling STRB");
 229                         end
 230                         `LSR_BASEWB: begin
 231                                 outstall = 1;
 232                                 next_lsr_state = `LSR_WBFLUSH;
 233                         end
 234                         `LSR_WBFLUSH: begin
 235                                 outstall = 0;
 236                                 next_lsr_state = `LSR_MEMIO;
 237                         end
 238                         default: begin
 239                                 outstall = 1'bx;
 240                                 next_lsr_state = 4'bxxxx;
 241                         end
 242                         endcase
 243                         $display("LDRSTR: Decoded, bubble %d, insn %08x, lsm state %b -> %b, stall %d", inbubble, insn, lsr_state, next_lsr_state, outstall);
 244                 end
 245                 `DECODE_LDMSTM: if(!inbubble) begin
 246                         outstall = rw_wait;
 247                         case(lsm_state)
 248                         `LSM_SETUP: begin
 249                                 outstall = 1'b1;
 250                                 next_lsm_state = `LSM_MEMIO;
 251                                 if (flush) begin
 252                                         outstall = 1'b0;
 253                                         next_lsm_state = `LSM_SETUP;
 254                                 end
 255                                 $display("LDMSTM: Round 1: base register: %08x, reg list %b", op0, op1[15:0]);
 256                         end
 257                         `LSM_MEMIO: begin
 258                                 outstall = 1'b1;
 259                                 if(next_regs == 16'b0) begin
 260                                         next_lsm_state = `LSM_BASEWB;
 261                                 end
 262
 263                                 $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);
 264                         end
 265                         `LSM_BASEWB: begin
 266                                 outstall = 1;
 267                                 next_lsm_state = `LSM_WBFLUSH;
 268                                 $display("LDMSTM: Stage 3: Writing back");
 269                         end
 270                         `LSM_WBFLUSH: begin
 271                                 outstall = 0;
 272                                 next_lsm_state = `LSM_SETUP;
 273                         end
 274                         default: begin
 275                                 outstall = 1'bx;
 276                                 next_lsm_state = 4'bxxxx;
 277                         end
 278                         endcase
 279                         $display("LDMSTM: Decoded, bubble %d, insn %08x, lsm state %b -> %b, stall %d", inbubble, insn, lsm_state, next_lsm_state, outstall);
 280                 end
 281                 `DECODE_LDCSTC: if(!inbubble) begin
 282                         $display("WARNING: Unimplemented LDCSTC");
 283                 end
 284                 `DECODE_CDP: if (!inbubble) begin
 285                         if (cp_busy) begin
 286                                 outstall = 1;
 287                         end
 288                         if (!cp_ack) begin
 289                                 /* XXX undefined instruction trap */
 290                                 $display("WARNING: Possible CDP undefined instruction");
 291                         end
 292                 end
 293                 `DECODE_MRCMCR: if (!inbubble) begin
 294                         if (cp_busy) begin
 295                                 outstall = 1;
 296                         end
 297                         if (!cp_ack) begin
 298                                 $display("WARNING: Possible MRCMCR undefined instruction: cp_ack %d, cp_busy %d",cp_ack, cp_busy);
 299                         end
 300                         $display("MRCMCR: ack %d, busy %d", cp_ack, cp_busy);
 301                 end
 302                 default: begin end
 303                 endcase
 304         end
 305
 306         /* Coprocessor input. */
 307         always @(*)
 308         begin
 309                 cp_req = 0;
 310                 cp_rnw = 1'bx;
 311                 cp_write = 32'hxxxxxxxx;
 312                 casez (insn)
 313                 `DECODE_CDP: if(!inbubble) begin
 314                         cp_req = 1;
 315                 end
 316                 `DECODE_MRCMCR: if(!inbubble) begin
 317                         cp_req = 1;
 318                         cp_rnw = insn[20] /* L */;
 319                         if (insn[20] == 0 /* store to coprocessor */)
 320                                 cp_write = op0;
 321                 end
 322                 endcase
 323         end
 324
 325         /* Register output logic. */
 326         always @(*)
 327         begin
 328                 next_write_reg = write_reg;
 329                 next_write_num = write_num;
 330                 next_write_data = write_data;
 331                 next_outcpsr = lsm_state == 4'b0010 ? outcpsr : cpsr;
 332                 next_outcpsrup = cpsrup;
 333
 334                 casez(insn)
 335                 `DECODE_ALU_SWP: if (!inbubble) begin
 336                         next_write_reg = 1'bx;
 337                         next_write_num = 4'bxxxx;
 338                         next_write_data = 32'hxxxxxxxx;
 339                         case(swp_state)
 340                         `SWP_READING:
 341                                 next_write_reg = 1'b0;
 342                         `SWP_WRITING: begin
 343                                 next_write_reg = 1'b1;
 344                                 next_write_num = insn[15:12];
 345                                 next_write_data = insn[22] ? {24'b0, swp_oldval[7:0]} : swp_oldval;
 346                         end
 347                         default: begin end
 348                         endcase
 349                 end
 350                 `DECODE_ALU_MULT: begin end
 351                 `DECODE_ALU_HDATA_REG,
 352                 `DECODE_ALU_HDATA_IMM: if(!inbubble) begin
 353                         next_write_reg = 1'bx;
 354                         next_write_num = 4'bxxxx;
 355                         next_write_data = 32'hxxxxxxxx;
 356                         case(lsrh_state)
 357                         `LSRH_MEMIO: begin
 358                                 next_write_num = insn[15:12];
 359                                 next_write_data = lsrh_rddata;
 360                                 if(insn[20]) begin
 361                                         next_write_reg = 1'b1;
 362                                 end
 363                         end
 364                         `LSRH_BASEWB: begin
 365                                 next_write_reg = 1'b1;
 366                                 next_write_num = insn[19:16];
 367                                 next_write_data = addr;
 368                         end
 369                         `LSRH_WBFLUSH:
 370                                 next_write_reg = 1'b0;
 371                         default: begin end
 372                         endcase
 373                 end
 374                 `DECODE_LDRSTR_UNDEFINED: begin end
 375                 `DECODE_LDRSTR: if(!inbubble) begin
 376                         next_write_reg = 1'bx;
 377                         next_write_num = 4'bxxxx;
 378                         next_write_data = 32'hxxxxxxxx;
 379                         case(lsr_state)
 380                         `LSR_MEMIO: begin
 381                                 next_write_reg = insn[20] /* L */;
 382                                 next_write_num = insn[15:12];
 383                                 if(insn[20] /* L */) begin
 384                                         next_write_data = insn[22] /* B */ ? {24'h0, align_rddata[7:0]} : align_rddata;
 385                                 end
 386                         end
 387                         `LSR_STRB_WR:
 388                                 next_write_reg = 1'b0;
 389                         `LSR_BASEWB: begin
 390                                 next_write_reg = 1'b1;
 391                                 next_write_num = insn[19:16];
 392                                 next_write_data = addr;
 393                         end
 394                         `LSR_WBFLUSH:
 395                                 next_write_reg = 1'b0;
 396                         default: begin end
 397                         endcase
 398                 end
 399                 `DECODE_LDMSTM: if(!inbubble) begin
 400                         next_write_reg = 1'bx;
 401                         next_write_num = 4'bxxxx;
 402                         next_write_data = 32'hxxxxxxxx;
 403                         case(lsm_state)
 404                         `LSM_SETUP:
 405                                 next_write_reg = 1'b0;
 406                         `LSM_MEMIO: begin
 407                                 if(insn[20]) begin
 408                                         next_write_reg = !rw_wait;
 409                                         next_write_num = cur_reg;
 410                                         next_write_data = rd_data;
 411                                 end else
 412                                         next_write_reg = 1'b0;
 413                         end
 414                         `LSM_BASEWB: begin
 415                                 next_write_reg = insn[21] /* writeback */;
 416                                 next_write_num = insn[19:16];
 417                                 next_write_data = insn[23] ? op0 + {26'b0, prev_offset} : op0 - {26'b0, prev_offset};
 418                                 if(cur_reg == 4'hF && insn[22]) begin
 419                                         next_outcpsr = spsr;
 420                                         next_outcpsrup = 1;
 421                                 end
 422                         end
 423                         `LSM_WBFLUSH:
 424                                 next_write_reg = 1'b0;
 425                         default: begin end
 426                         endcase
 427                 end
 428                 `DECODE_MRCMCR: if(!inbubble) begin
 429                         next_write_reg = 1'bx;
 430                         next_write_num = 4'bxxxx;
 431                         next_write_data = 32'hxxxxxxxx;
 432                         next_outcpsr = 32'hxxxxxxxx;
 433                         next_outcpsrup = 1'bx;
 434                         if (insn[20] == 1 /* load from coprocessor */)
 435                                 if (insn[15:12] != 4'hF /* Fuck you ARM */) begin
 436                                         next_write_reg = 1'b1;
 437                                         next_write_num = insn[15:12];
 438                                         next_write_data = cp_read;
 439                                 end else begin
 440                                         next_outcpsr = {cp_read[31:28], cpsr[27:0]};
 441                                         next_outcpsrup = 1;
 442                                 end
 443                 end
 444                 endcase
 445         end
 446
 447         /* Bus control logic. */
 448         always @(*)
 449         begin
 450                 rd_req = 1'b0;
 451                 wr_req = 1'b0;
 452                 wr_data = 32'hxxxxxxxx;
 453                 busaddr = 32'hxxxxxxxx;
 454                 data_size = 3'bxxx;
 455
 456                 casez(insn)
 457                 `DECODE_ALU_SWP: if(!inbubble) begin
 458                         busaddr = {op0[31:2], 2'b0};
 459                         data_size = insn[22] ? 3'b001 : 3'b100;
 460                         case(swp_state)
 461                         `SWP_READING:
 462                                 rd_req = 1'b1;
 463                         `SWP_WRITING: begin
 464                                 wr_req = 1'b1;
 465                                 wr_data = insn[22] ? {4{op1[7:0]}} : op1;
 466                         end
 467                         default: begin end
 468                         endcase
 469                 end
 470                 `DECODE_ALU_MULT: begin end
 471                 `DECODE_ALU_HDATA_REG,
 472                 `DECODE_ALU_HDATA_IMM: if(!inbubble) begin
 473                         busaddr = raddr;
 474                         /* rotate to correct position */
 475                         case(insn[6:5])
 476                         2'b01: begin /* unsigned half */
 477                                 wr_data = {2{op2[15:0]}}; /* XXX need to store halfword */
 478                                 data_size = 3'b010;
 479                         end
 480                         2'b10: begin /* signed byte */
 481                                 wr_data = {4{op2[7:0]}};
 482                                 data_size = 3'b001;
 483                         end
 484                         2'b11: begin /* signed half */
 485                                 wr_data = {2{op2[15:0]}};
 486                                 data_size = 3'b010;
 487                         end
 488                         default: begin
 489                                 wr_data = 32'hxxxxxxxx;
 490                                 data_size = 3'bxxx;
 491                         end
 492                         endcase
 493
 494                         case(lsrh_state)
 495                         `LSRH_MEMIO: begin
 496                                 rd_req = insn[20];
 497                                 wr_req = ~insn[20];
 498                         end
 499                         `LSRH_BASEWB: begin end
 500                         `LSRH_WBFLUSH: begin end
 501                         default: begin end
 502                         endcase
 503                 end
 504                 `DECODE_LDRSTR_UNDEFINED: begin end
 505                 `DECODE_LDRSTR: if(!inbubble) begin
 506                         busaddr = raddr;
 507                         wr_data = insn[22] ? {24'h0, {op2[7:0]}} : op2;
 508                         data_size = insn[22] ? 3'b001 : 3'b100;
 509                         case (lsr_state)
 510                         `LSR_MEMIO: begin
 511                                 rd_req = insn[20] /* L */ || insn[22] /* B */;
 512                                 wr_req = !insn[20] /* L */ && !insn[22]/* B */;
 513                         end
 514                         `LSR_STRB_WR: begin
 515                                 wr_req = 1;
 516                                 case (busaddr[1:0])
 517                                 2'b00: wr_data = {rd_data_latch[31:8], op2[7:0]};
 518                                 2'b01: wr_data = {rd_data_latch[31:16], op2[7:0], rd_data_latch[7:0]};
 519                                 2'b10: wr_data = {rd_data_latch[31:24], op2[7:0], rd_data_latch[15:0]};
 520                                 2'b11: wr_data = {op2[7:0], rd_data_latch[23:0]};
 521                                 endcase
 522                         end
 523                         `LSR_BASEWB: begin end
 524                         `LSR_WBFLUSH: begin end
 525                         default: begin end
 526                         endcase
 527                 end
 528                 `DECODE_LDMSTM: if (!inbubble) begin
 529                         data_size = 3'b100;
 530                         case (lsm_state)
 531                         `LSM_SETUP: begin end
 532                         `LSM_MEMIO: begin
 533                                 rd_req = insn[20];
 534                                 wr_req = ~insn[20];
 535                                 wr_data = (cur_reg == 4'hF) ? (pc + 12) : st_data;
 536                                 busaddr = raddr;
 537                         end
 538                         `LSM_BASEWB: begin end
 539                         `LSM_WBFLUSH: begin end
 540                         default: begin end
 541                         endcase
 542                 end
 543                 `DECODE_LDCSTC: begin end
 544                 `DECODE_CDP: begin end
 545                 `DECODE_MRCMCR: begin end
 546                 default: begin end
 547                 endcase
 548         end
 549
 550         always @(*)
 551         begin
 552                 addr = prevaddr;
 553                 raddr = 32'hxxxxxxxx;
 554                 st_read = 4'hx;
 555                 do_rd_data_latch = 0;
 556
 557                 next_outbubble = inbubble;
 558                 next_regs = regs;
 559
 560                 offset = prev_offset;
 561                 lsrh_rddata = 32'hxxxxxxxx;
 562                 lsrh_rddata_s1 = 16'hxxxx;
 563                 lsrh_rddata_s2 = 8'hxx;
 564                 next_swp_oldval = swp_oldval;
 565                 cur_reg = prev_reg;
 566
 567                 /* XXX shit not given about endianness */
 568                 casez(insn)
 569                 `DECODE_ALU_SWP: if(!inbubble) begin
 570                         next_outbubble = rw_wait;
 571                         case(swp_state)
 572                         `SWP_READING:
 573                                 if(!rw_wait)
 574                                         next_swp_oldval = rd_data;
 575                         `SWP_WRITING: begin end
 576                         default: begin end
 577                         endcase
 578                 end
 579                 `DECODE_ALU_MULT: begin end
 580                 `DECODE_ALU_HDATA_REG,
 581                 `DECODE_ALU_HDATA_IMM: if(!inbubble) begin
 582                         next_outbubble = rw_wait;
 583                         addr = insn[23] ? op0 + op1 : op0 - op1; /* up/down select */
 584                         raddr = insn[24] ? op0 : addr; /* pre/post increment */
 585                         /* rotate to correct position */
 586                         case(insn[6:5])
 587                         2'b01: begin /* unsigned half */
 588                                 lsrh_rddata = {16'b0, raddr[1] ? rd_data[31:16] : rd_data[15:0]};
 589                         end
 590                         2'b10: begin /* signed byte */
 591                                 lsrh_rddata_s1 = raddr[1] ? rd_data[31:16] : rd_data[15:0];
 592                                 lsrh_rddata_s2 = raddr[0] ? lsrh_rddata_s1[15:8] : lsrh_rddata_s1[7:0];
 593                                 lsrh_rddata = {{24{lsrh_rddata_s2[7]}}, lsrh_rddata_s2};
 594                         end
 595                         2'b11: begin /* signed half */
 596                                 lsrh_rddata = raddr[1] ? {{16{rd_data[31]}}, rd_data[31:16]} : {{16{rd_data[15]}}, rd_data[15:0]};
 597                         end
 598                         default: begin
 599                                 lsrh_rddata = 32'hxxxxxxxx;
 600                         end
 601                         endcase
 602
 603                         case(lsrh_state)
 604                         `LSRH_MEMIO: begin end
 605                         `LSRH_BASEWB:
 606                                 next_outbubble = 1'b0;
 607                         `LSRH_WBFLUSH: begin end
 608                         default: begin end
 609                         endcase
 610                 end
 611                 `DECODE_LDRSTR_UNDEFINED: begin end
 612                 `DECODE_LDRSTR: if(!inbubble) begin
 613                         next_outbubble = rw_wait;
 614                         addr = insn[23] ? op0 + op1 : op0 - op1; /* up/down select */
 615                         raddr = insn[24] ? addr : op0; /* pre/post increment */
 616                         /* rotate to correct position */
 617                         align_s1 = raddr[1] ? {rd_data[15:0], rd_data[31:16]} : rd_data;
 618                         align_s2 = raddr[0] ? {align_s1[7:0], align_s1[31:8]} : align_s1;
 619                         /* select byte or word */
 620                         align_rddata = insn[22] ? {24'b0, align_s2[7:0]} : align_s2;
 621                         case(lsr_state)
 622                         `LSR_MEMIO:
 623                                 if (insn[22] /* B */ && !insn[20] /* L */)
 624                                         do_rd_data_latch = 1;
 625                         `LSR_STRB_WR: begin end
 626                         `LSR_BASEWB:
 627                                 next_outbubble = 0;
 628                         `LSR_WBFLUSH: begin end
 629                         default: begin end
 630                         endcase
 631                 end
 632                 /* XXX ldm/stm incorrect in that stupid case where one of the listed regs is the base reg */
 633                 `DECODE_LDMSTM: if(!inbubble) begin
 634                         next_outbubble = rw_wait;
 635                         case(lsm_state)
 636                         `LSM_SETUP: begin
 637 //                              next_regs = insn[23] ? op1[15:0] : op1[0:15];
 638                                 /** verilator can suck my dick */
 639                                 next_regs = insn[23] /* U */ ? op1[15:0] : {op1[0], op1[1], op1[2], op1[3], op1[4], op1[5], op1[6], op1[7],
 640                                                                             op1[8], op1[9], op1[10], op1[11], op1[12], op1[13], op1[14], op1[15]};
 641                                 offset = 6'b0;
 642                         end
 643                         `LSM_MEMIO: begin
 644                                 casez(regs)
 645                                 16'b???????????????1: begin
 646                                         cur_reg = 4'h0;
 647                                         next_regs = {regs[15:1], 1'b0};
 648                                 end
 649                                 16'b??????????????10: begin
 650                                         cur_reg = 4'h1;
 651                                         next_regs = {regs[15:2], 2'b0};
 652                                 end
 653                                 16'b?????????????100: begin
 654                                         cur_reg = 4'h2;
 655                                         next_regs = {regs[15:3], 3'b0};
 656                                 end
 657                                 16'b????????????1000: begin
 658                                         cur_reg = 4'h3;
 659                                         next_regs = {regs[15:4], 4'b0};
 660                                 end
 661                                 16'b???????????10000: begin
 662                                         cur_reg = 4'h4;
 663                                         next_regs = {regs[15:5], 5'b0};
 664                                 end
 665                                 16'b??????????100000: begin
 666                                         cur_reg = 4'h5;
 667                                         next_regs = {regs[15:6], 6'b0};
 668                                 end
 669                                 16'b?????????1000000: begin
 670                                         cur_reg = 4'h6;
 671                                         next_regs = {regs[15:7], 7'b0};
 672                                 end
 673                                 16'b????????10000000: begin
 674                                         cur_reg = 4'h7;
 675                                         next_regs = {regs[15:8], 8'b0};
 676                                 end
 677                                 16'b???????100000000: begin
 678                                         cur_reg = 4'h8;
 679                                         next_regs = {regs[15:9], 9'b0};
 680                                 end
 681                                 16'b??????1000000000: begin
 682                                         cur_reg = 4'h9;
 683                                         next_regs = {regs[15:10], 10'b0};
 684                                 end
 685                                 16'b?????10000000000: begin
 686                                         cur_reg = 4'hA;
 687                                         next_regs = {regs[15:11], 11'b0};
 688                                 end
 689                                 16'b????100000000000: begin
 690                                         cur_reg = 4'hB;
 691                                         next_regs = {regs[15:12], 12'b0};
 692                                 end
 693                                 16'b???1000000000000: begin
 694                                         cur_reg = 4'hC;
 695                                         next_regs = {regs[15:13], 13'b0};
 696                                 end
 697                                 16'b??10000000000000: begin
 698                                         cur_reg = 4'hD;
 699                                         next_regs = {regs[15:14], 14'b0};
 700                                 end
 701                                 16'b?100000000000000: begin
 702                                         cur_reg = 4'hE;
 703                                         next_regs = {regs[15], 15'b0};
 704                                 end
 705                                 16'b1000000000000000: begin
 706                                         cur_reg = 4'hF;
 707                                         next_regs = 16'b0;
 708                                 end
 709                                 default: begin
 710                                         cur_reg = 4'hx;
 711                                         next_regs = 16'b0;
 712                                 end
 713                                 endcase
 714                                 cur_reg = insn[23] ? cur_reg : 4'hF - cur_reg;
 715
 716                                 offset = prev_offset + 6'h4;
 717                                 offset_sel = insn[24] ? offset : prev_offset;
 718                                 raddr = insn[23] ? op0 + {26'b0, offset_sel} : op0 - {26'b0, offset_sel};
 719                                 if (rw_wait) begin
 720                                         next_regs = regs;
 721                                         cur_reg = prev_reg;     /* whoops, do this one again */
 722                                 end
 723
 724                                 st_read = cur_reg;
 725                         end
 726                         `LSM_BASEWB:
 727                                 next_outbubble = 0;
 728                         `LSM_WBFLUSH: begin end
 729                         default: $stop;
 730                         endcase
 731                 end
 732                 `DECODE_LDCSTC: begin end
 733                 `DECODE_CDP: if(!inbubble) begin
 734                         if (cp_busy) begin
 735                                 next_outbubble = 1;
 736                         end
 737                 end
 738                 `DECODE_MRCMCR: if(!inbubble) begin
 739                         if (cp_busy) begin
 740                                 next_outbubble = 1;
 741                         end
 742                 end
 743                 default: begin end
 744                 endcase
 745
 746                 if ((flush || delayedflush) && !outstall)
 747                         next_outbubble = 1'b1;
 748         end
 749 endmodule