ships/Memory.ship

   1 ship: Memory
   2
   3 == Ports ===========================================================
   4 data  in:    inCBD
   5 data  in:    inAddrRead
   6 data  in:    inAddrWrite
   7 data  in:    inDataWrite
   8 data  in:    inStride
   9 data  in:    inCount
  10
  11 data  out:   out
  12
  13 == TeX ==============================================================
  14
  15 The {\tt Memory} ship represents an interface to a storage space,
  16 which can be used to read from it or write to it.  This storage space
  17 might be a fast on-chip cache, off chip DRAM, or perhaps even a disk drive.
  18
  19 There may be multiple {\tt Memory} ships which interface to the same
  20 physical storage space.  An implementation of Fleet must provide
  21 additional documentation to the programmer indicating which {\tt
  22 Memory} ships correspond to which storage spaces.  A single {\tt
  23 Memory} ship may also access a ``virtual storage space'' formed by
  24 concatenating multiple physical storage spaces.
  25
  26 \subsection*{Code Bag Fetch}
  27
  28 When a word appears at the {\tt inCBD} port, it is treated as a {\it
  29 code bag descriptor}, as shown below:
  30
  31 \begin{center}
  32 \setlength{\bitwidth}{3mm}
  33 {\tt
  34 \begin{bytefield}{37}
  35   \bitheader[b]{36,6,5,0}\\
  36   \bitbox{31}{Address}
  37   \bitbox{6}{size}
  38 \end{bytefield}
  39 }
  40 \end{center}
  41
  42 When a word arrives at the {\tt inCBD} port, it is treated as a memory
  43 read with {\tt inAddrRead=Address}, {\tt inStride=1}, and {\tt
  44 inCount=size}.
  45
  46 \subsection*{Reading}
  47
  48 When a word is delivered to {\tt inAddrRead}, the word residing in
  49 memory at that address is provided at {\tt out}.
  50
  51 \subsection*{Writing}
  52
  53 When a word is delivered to {\tt inAddrWrite} and {\tt inDataWrite},
  54 the word at {\tt inDataWrite} is written to the address specified by
  55 {\tt inAddrWrite}.  Once the word is successfully committed to memory,
  56 the value {\tt inAddr+inStride} is provided at {\tt out} (that is, the
  57 address of the next word to be written).
  58
  59 \subsection*{To Do}
  60
  61 Stride and count are not implemented.
  62
  63 We need a way to do an ``unordered fetch'' -- a way to tell the memory
  64 unit to retrieve some block of words in any order it likes.  This can
  65 considerably accelerate fetches when the first word of the region is
  66 not cached, but other parts are cached.  This can also be used for
  67 dispatching codebags efficiently -- but how will we make sure that
  68 instructions destined for a given pump are dispatched in the correct
  69 order (source sequence guarantee)?
  70
  71 A more advanced form would be ``unordered fetch of ordered records''
  72 -- the ability to specify a record size (in words), the offset of the
  73 first record, and the number of records to be fetched.  The memory
  74 unit would then fetch the records in any order it likes, but would be
  75 sure to return the words comprising a record in the order in which
  76 they appear in memory.  This feature could be used to solve the source
  77 sequence guarantee problem mentioned in the previous paragraph.
  78
  79 == Fleeterpreter ====================================================
  80     private long[] mem = new long[0];
  81     public long readMem(int addr) { return mem[addr]; }
  82     public void writeMem(int addr, long val) {
  83         if (addr >= mem.length) {
  84             long[] newmem = new long[addr * 2 + 1];
  85             System.arraycopy(mem, 0, newmem, 0, mem.length);
  86             mem = newmem;
  87         }
  88         mem[addr] = val;
  89     }
  90
  91     public void dispatch(int addr, int size) {
  92         for(int i=addr; i<addr+size; i++) {
  93             Instruction instr = ((Interpreter)getFleet()).readInstruction(readMem(i));
  94             ((Interpreter)getFleet()).dispatch(instr, i);
  95         }
  96     }
  97
  98     public void boot(byte[] instructions) {
  99         Interpreter fleet = (Interpreter)getFleet();
 100         // load the iscratch and take note of the 0-address INCBD
 101         long launch = 0;
 102         for(int i=0; i<instructions.length; i+=6) {
 103             long word = 0;
 104             for(int j=0; j<6; j++)
 105                 word = (word << 8) | (instructions[i+j] & 0xff);
 106             writeMem(i/6, word);
 107             if (i==0) launch = word;
 108         }
 109
 110         // dispatch the 0-address INCBD
 111         int base = (int)(launch >> 6);
 112         base = base & ~(0xffffffff << 18);
 113         int size = (int)launch;
 114         size = size & ~(0xffffffff <<  6);
 115         dispatch(base, size);
 116     }
 117
 118     private long stride = 0;
 119     private long count = 0;
 120     private long addr = 0;
 121     private boolean writing = false;
 122
 123     public void service() {
 124         if (box_inCBD.dataReadyForShip()) {
 125             long val = box_inCBD.removeDataForShip();
 126             long addr = val >> 6;
 127             long size = val & 0x3f;
 128             dispatch((int)addr, (int)size);
 129         }
 130         if (count > 0) {
 131             if (writing) {
 132               if (box_inDataWrite.dataReadyForShip() && box_out.readyForDataFromShip()) {
 133                  writeMem((int)addr, box_inDataWrite.removeDataForShip());
 134                  box_out.addDataFromShip(0);
 135                  count--;
 136                  addr += stride;
 137               }
 138             } else {
 139               if (box_out.readyForDataFromShip()) {
 140                  box_out.addDataFromShip(readMem((int)addr));
 141                  count--;
 142                  addr += stride;
 143               }
 144             }
 145
 146         } else if (box_inAddrRead.dataReadyForShip()) {
 147             addr = box_inAddrRead.removeDataForShip();
 148             stride = 0;
 149             count = 1;
 150             writing = false;
 151
 152         } else if (box_inAddrWrite.dataReadyForShip()) {
 153             addr = box_inAddrWrite.peekPacketForShip().value;
 154             box_inAddrWrite.removeDataForShip();
 155             stride = 0;
 156             count = 1;
 157             writing = true;
 158         }
 159     }
 160
 161 == FleetSim ==============================================================
 162
 163 == FPGA ==============================================================
 164 `include "macros.v"
 165 `define BRAM_ADDR_WIDTH 14
 166 `define BRAM_DATA_WIDTH `INSTRUCTION_WIDTH
 167 `define BRAM_NAME some_bram
 168
 169 /* bram.inc */
 170 module `BRAM_NAME(clk, rst, we, a, dpra, di, spo, dpo);
 171     input  clk;
 172     input  rst;
 173     input  we;
 174     input  [(`BRAM_ADDR_WIDTH-1):0] a;
 175     input  [(`BRAM_ADDR_WIDTH-1):0] dpra;
 176     input  [(`BRAM_DATA_WIDTH-1):0] di;
 177     output [(`BRAM_DATA_WIDTH-1):0] spo;
 178     output [(`BRAM_DATA_WIDTH-1):0] dpo;
 179     reg    [(`BRAM_DATA_WIDTH-1):0] ram [((1<<(`BRAM_ADDR_WIDTH))-1):0];
 180     reg    [(`BRAM_ADDR_WIDTH-1):0] read_a;
 181     reg    [(`BRAM_ADDR_WIDTH-1):0] read_dpra;
 182     always @(posedge clk) begin
 183         if (we)
 184             ram[a] <= di;
 185         read_a <= a;
 186         read_dpra <= dpra;
 187     end
 188     assign spo = ram[read_a];
 189     assign dpo = ram[read_dpra];
 190 endmodule
 191 /* bram.inc */
 192
 193 module memory (clk, rst,
 194                cbd_r,          cbd_a_,         cbd_d,
 195                in_addr_r,      in_addr_a_,     in_addr_d,
 196                write_addr_r,   write_addr_a_,  write_addr_d,
 197                write_data_r,   write_data_a_,  write_data_d,
 198                stride_r,       stride_a_,      stride_d,
 199                count_r,        count_a_,       count_d,
 200                out_r_,         out_a,          out_d_,
 201                preload_r,      preload_a_,     preload_d,
 202                ihorn_r_,       ihorn_a,        ihorn_d_,
 203                dhorn_r_,       dhorn_a,        dhorn_d_
 204               );
 205
 206   input  clk;
 207   input  rst;
 208   `input(in_addr_r,      in_addr_a,     in_addr_a_,     [(2+`DATAWIDTH-1):0],       in_addr_d)
 209   `input(write_addr_r,   write_addr_a,  write_addr_a_,  [(2+`DATAWIDTH-1):0],       write_addr_d)
 210   `input(write_data_r,   write_data_a,  write_data_a_,  [(`DATAWIDTH-1):0],         write_data_d)
 211   `input(stride_r,       stride_a,      stride_a_,      [(`DATAWIDTH-1):0],         stride_d)
 212   `input(count_r,        count_a,       count_a_,       [(`DATAWIDTH-1):0],         count_d)
 213   `output(out_r,         out_r_,        out_a,          [(`DATAWIDTH-1):0],         out_d_)
 214   `input(preload_r,      preload_a,     preload_a_,     [(`DATAWIDTH-1):0],         preload_d)
 215   `input(cbd_r,          cbd_a,         cbd_a_,         [(`DATAWIDTH-1):0],         cbd_d)
 216   `output(ihorn_r,       ihorn_r_,      ihorn_a,        [(`PACKET_WIDTH-1):0], ihorn_d_)
 217   `defreg(ihorn_d_,                                     [(`PACKET_WIDTH-1):0], ihorn_d)
 218   `output(dhorn_r,       dhorn_r_,      dhorn_a,        [(`PACKET_WIDTH-1):0],      dhorn_d_)
 219   `defreg(dhorn_d_,                                     [(`PACKET_WIDTH-1):0],      dhorn_d)
 220
 221   reg ihorn_full;
 222   initial ihorn_full = 0;
 223   reg dhorn_full;
 224   initial dhorn_full = 0;
 225   reg command_valid;
 226   initial command_valid = 0;
 227
 228   reg [(`BRAM_ADDR_WIDTH-1):0]    preload_pos;
 229   reg [(`BRAM_ADDR_WIDTH-1):0]    preload_size;
 230   initial preload_size = 0;
 231
 232   reg [(`BRAM_ADDR_WIDTH-1):0]    current_instruction_read_from;
 233   reg [(`BRAM_ADDR_WIDTH-1):0]    temp_base;
 234   reg [(`CODEBAG_SIZE_BITS-1):0]  temp_size;
 235   reg [(`BRAM_ADDR_WIDTH-1):0]    cbd_base;
 236   reg [(`CODEBAG_SIZE_BITS-1):0]  cbd_size;
 237   reg [(`CODEBAG_SIZE_BITS-1):0]  cbd_pos;
 238   reg [(`INSTRUCTION_WIDTH-1):0]  command;
 239   reg [(`BRAM_DATA_WIDTH-1):0]    ram [((1<<(`BRAM_ADDR_WIDTH))-1):0];
 240   reg                             send_done;
 241   reg                             send_read;
 242
 243   reg [(`INSTRUCTION_WIDTH-(2+`DESTINATION_ADDRESS_BITS)):0] temp;
 244   reg [(`DATAWIDTH-1):0]                                     data;
 245
 246   reg                             write_flag;
 247   reg [(`BRAM_ADDR_WIDTH-1):0]    in_addr;
 248   reg [(`BRAM_DATA_WIDTH-1):0]    write_data;
 249
 250   wire [(`BRAM_DATA_WIDTH-1):0]   ramread;
 251
 252   reg command_valid_read;
 253   initial command_valid_read = 0;
 254
 255   reg launched;
 256   initial launched = 0;
 257
 258   some_bram mybram(clk, rst, write_flag, in_addr, current_instruction_read_from, write_data, not_connected, ramread);
 259   assign out_d_ = ramread;
 260
 261   always @(posedge clk /*or negedge rst*/) begin
 262
 263     if (!rst) begin
 264       ihorn_full <= 0;
 265       dhorn_full <= 0;
 266       command_valid <= 0;
 267 /*
 268       preload_size <= 0;
 269 */
 270       launched <= 0;
 271       command_valid_read <= 0;
 272       write_flag <= 0;
 273
 274       dhorn_r <= 0;
 275       ihorn_r <= 0;
 276       out_r <= 0;
 277
 278     end else begin
 279
 280     write_flag <= 0;
 281
 282     if (!in_addr_r && in_addr_a) in_addr_a = 0;
 283     if (!write_data_r && write_data_a) write_data_a = 0;
 284     if (!write_addr_r && write_addr_a) write_addr_a = 0;
 285
 286     if (command_valid_read) begin
 287       command_valid_read  <= 0;
 288       command_valid       <= 1;
 289
 290     end else  if (send_done) begin
 291       `onwrite(out_r, out_a)
 292         send_done <= 0;
 293       end
 294
 295     end else  if (send_read) begin
 296       `onwrite(out_r, out_a)
 297         send_read <= 0;
 298       end
 299
 300     end else if (in_addr_r) begin
 301       in_addr_a                        = 1;
 302       send_read                       <= 1;
 303       current_instruction_read_from   <= in_addr_d[(`DATAWIDTH-1):0];
 304
 305     end else if (write_addr_r && write_data_r) begin
 306       write_addr_a       = 1;
 307       write_data_a       = 1;
 308       send_done         <= 1;
 309       write_flag        <= 1;
 310       in_addr           <= write_addr_d[(`DATAWIDTH-1):0];
 311       write_data        <= write_data_d;
 312
 313     end else if (ihorn_full && launched) begin
 314       `onwrite(ihorn_r, ihorn_a)
 315         ihorn_full <= 0;
 316       end
 317
 318     end else if (dhorn_full) begin
 319       `onwrite(dhorn_r, dhorn_a)
 320         dhorn_full <= 0;
 321       end
 322
 323     end else if (command_valid) begin
 324       command_valid <= 0;
 325       command = ramread;
 326       ihorn_full  <= 1;
 327       `packet_data(ihorn_d) <= `instruction_data(command);
 328       `packet_dest(ihorn_d) <= `instruction_dest(command);
 329
 330     end else if (cbd_pos < cbd_size) begin
 331       current_instruction_read_from <= cbd_base+cbd_pos;
 332       command_valid_read            <= 1;
 333       cbd_pos                       <= cbd_pos + 1;
 334
 335     end else begin
 336       `onread(cbd_r, cbd_a)
 337         cbd_pos       <= 0;
 338         cbd_size      <= cbd_d[(`CODEBAG_SIZE_BITS-1):0];
 339         cbd_base      <= cbd_d[(`INSTRUCTION_WIDTH-1):(`CODEBAG_SIZE_BITS)];
 340
 341       end else begin
 342         `onread(preload_r, preload_a)
 343           if (preload_size == 0) begin
 344             preload_size     <= preload_d;
 345           end else if (!launched) begin
 346             write_flag <= 1;
 347             write_data <= preload_d;
 348             in_addr <= preload_pos;
 349             if (preload_pos == 0) begin
 350               temp_base = preload_d[(`INSTRUCTION_WIDTH-(3+`DESTINATION_ADDRESS_BITS)):(`CODEBAG_SIZE_BITS)];
 351               temp_size = preload_d[(`CODEBAG_SIZE_BITS-1):0];
 352             end
 353             if ((preload_pos+1) == preload_size) begin
 354               cbd_pos  <= 0;
 355               cbd_base <= temp_base;
 356               cbd_size <= temp_size;
 357               launched <= 1;
 358             end
 359             preload_pos      <= preload_pos + 1;
 360           end
 361         end
 362       end
 363
 364     end
 365
 366     end
 367   end
 368 endmodule
 369
 370
 371
 372
 373
 374 == Test ==============================================================
 375 // expected output
 376 #expect 12
 377 #expect 13
 378 #expect 14
 379
 380 // ships required in order to run this code
 381 #ship debug          : Debug
 382 #ship memory         : Memory
 383
 384 // instructions not in any codebag are part of the "root codebag"
 385 // which is dispatched when the code is loaded
 386
 387 memory.inCBD:
 388   literal BOB;
 389   deliver;
 390
 391 BOB: {
 392   debug.in:
 393     literal 12; deliver;
 394     literal 13; deliver;
 395     literal 14; deliver;
 396 }
 397
 398
 399 == Constants ========================================================
 400
 401 == Contributors =========================================================
 402 Adam Megacz <megacz@cs.berkeley.edu>