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