13 files changed, 531 insertions, 0 deletions

diff --git a/sim/.gitignore b/sim/.gitignore
new file mode 100644
index 0000000..dc3fae8
--- /dev/null
+++ b/sim/.gitignore
@@ -0,0 +1,2 @@
+/build
+/verilator
diff --git a/sim/Makefile b/sim/Makefile
new file mode 100644
index 0000000..af9d22a
--- /dev/null
+++ b/sim/Makefile
@@ -0,0 +1,12 @@
+run: build/Vtop
+        $<
+.PHONY: run
+
+build/Vtop: $(wildcard *.cpp *.sv)
+        @rm -rf verilator
+        @mkdir -p build verilator
+        verilator +1800-2017ext+sv -Wall -Wno-BLKSEQ -Wno-UNUSED -O3 -Ihdl --Mdir verilator --trace --cc --build -j --exe --top-module top $(wildcard *.cpp *.sv)
+        @ln -t build -f verilator/Vtop
+        @rm -rf verilator
+
+.SECONDARY:
diff --git a/sim/alu.sv b/sim/alu.sv
new file mode 100644
index 0000000..407b083
--- /dev/null
+++ b/sim/alu.sv
@@ -0,0 +1,76 @@
+module alu
+    #(  parameter   UROM        = "<no file specified>"
+    ,   parameter   UIP_BITS    = 15
+    ,   parameter   UROM_BITS   = 8
+    ,   parameter   BUS_BITS    = 16
+    )
+    (   input   bit                 clk
+    ,   input   bit                 reset
+    ,   input   bit [UIP_BITS-1:0]  uip
+    ,   inout   bit [BUS_BITS-1:0]  abus
+    ,   inout   bit [BUS_BITS-1:0]  dbus
+    );
+
+bit [BUS_BITS-1:0] x;
+
+typedef enum
+    { OP
+    , OP_SEL0
+    , OP_SEL1
+    , OP_SEL2
+    , OUTADDR
+    , OUTDATA
+    } CtrlBit;
+
+bit [UROM_BITS-1:0] ctrl;
+urom#(UROM, UIP_BITS, UROM_BITS) urom(uip, ctrl);
+
+bit [2:0] sel;
+assign sel = {ctrl[OP_SEL2], ctrl[OP_SEL1], ctrl[OP_SEL0]};
+
+bit [BUS_BITS-1:0] and_result;
+bit [BUS_BITS-1:0] or_result;
+bit [BUS_BITS-1:0] xor_result;
+bit [BUS_BITS-1:0] add_result;
+bit [BUS_BITS-1:0] sub_result;
+bit [BUS_BITS-1:0] cmp_result;
+bit [BUS_BITS-1:0] lshift_result;
+bit [BUS_BITS-1:0] rshift_result;
+
+assign and_result = abus & dbus;
+assign or_result = abus | dbus;
+assign xor_result = abus ^ dbus;
+assign add_result = abus + dbus;
+assign sub_result = abus - dbus;
+assign cmp_result = {{(BUS_BITS-6){1'b0}},
+    (abus != 0) & (dbus != 0),
+    (abus != 0) | (dbus != 0),
+    (abus != 0) ^ (dbus != 0),
+    abus > dbus,
+    abus == dbus,
+    abus < dbus};
+assign lshift_result = (dbus >= BUS_BITS) ? 0 : (abus << dbus);
+assign rshift_result = (dbus >= BUS_BITS) ? 0 : (abus >> dbus);
+
+bit [BUS_BITS-1:0] newx;
+assign newx =
+    (sel == 0) ? and_result :
+    (sel == 1) ? or_result :
+    (sel == 2) ? xor_result :
+    (sel == 3) ? add_result :
+    (sel == 4) ? sub_result :
+    (sel == 5) ? cmp_result :
+    (sel == 6) ? lshift_result :
+    (sel == 7) ? rshift_result :
+    {(BUS_BITS){1'bX}};
+
+assign abus = ctrl[OUTADDR] ? x : {(BUS_BITS){1'bZ}};
+assign dbus = ctrl[OUTDATA] ? x : {(BUS_BITS){1'bZ}};
+
+always @(posedge clk) begin
+    if (ctrl[OP]) begin
+        x <= newx;
+    end
+end
+
+endmodule
diff --git a/sim/control.sv b/sim/control.sv
new file mode 100644
index 0000000..7808f61
--- /dev/null
+++ b/sim/control.sv
@@ -0,0 +1,54 @@
+module control
+    #(  parameter   UROM        = "<no file specified>"
+    ,   parameter   UIP_BITS    = 15
+    ,   parameter   UROM_BITS   = 8
+    ,   parameter   BUS_BITS    = 16
+    ,   parameter   CONST_0     = "<no file specified>"
+    ,   parameter   CONST_1     = "<no file specified>"
+    ,   parameter   RESET       = ~0
+    )
+    (   input   bit                 clk
+    ,   input   bit                 reset
+    ,   output  bit [UIP_BITS-1:0]  uip
+    ,   inout   bit [BUS_BITS-1:0]  abus
+    ,   inout   bit [BUS_BITS-1:0]  dbus
+    );
+
+typedef enum
+    { HALT
+    , SET_UIP_COND
+    , NOCOND
+    , OUTADDR
+    , OUTDATA
+    } CtrlBit;
+
+bit [UROM_BITS-1:0] ctrl;
+urom#(UROM, UIP_BITS, UROM_BITS) urom(uip, ctrl);
+
+bit [UROM_BITS*2-1:0] constant;
+urom#(CONST_0, UIP_BITS, UROM_BITS) const_0(uip, constant[1*UROM_BITS-1:0*UROM_BITS]);
+urom#(CONST_1, UIP_BITS, UROM_BITS) const_1(uip, constant[2*UROM_BITS-1:1*UROM_BITS]);
+
+assign abus = ctrl[OUTADDR] ? constant : {(BUS_BITS){1'bZ}};
+assign dbus = ctrl[OUTDATA] ? constant : {(BUS_BITS){1'bZ}};
+
+bit cond;
+assign cond = (dbus != 0) || ctrl[NOCOND];
+
+always @(posedge clk) begin
+    if (reset) begin
+        uip <= RESET;
+    end else begin
+        if (! ctrl[HALT]) begin
+            if (ctrl[SET_UIP_COND] && cond) begin
+                uip <= abus[UIP_BITS-1:0];
+            end else begin
+                uip <= uip + 1;
+            end
+        end else begin
+            $finish;
+        end
+    end
+end
+
+endmodule
diff --git a/sim/decode.sv b/sim/decode.sv
new file mode 100644
index 0000000..5c9a9c9
--- /dev/null
+++ b/sim/decode.sv
@@ -0,0 +1,82 @@
+module decode
+    #(  parameter   UROM        = "<no file specified>"
+    ,   parameter   UIP_BITS    = 15
+    ,   parameter   UROM_BITS   = 8
+    ,   parameter   BUS_BITS    = 16
+    ,   parameter   OPCODE_BITS = 8
+    )
+    (   input   bit                 clk
+    ,   input   bit                 reset
+    ,   input   bit [UIP_BITS-1:0]  uip
+    ,   inout   bit [BUS_BITS-1:0]  abus
+    ,   inout   bit [BUS_BITS-1:0]  dbus
+    );
+
+bit [OPCODE_BITS-1:0] opcode;
+bit [BUS_BITS-1:0] a;
+bit [BUS_BITS-1:0] b;
+bit needmore;
+
+bit [UIP_BITS-1:0] new_uip;
+assign new_uip = {opcode, {(UIP_BITS-OPCODE_BITS){1'b0}}};
+
+typedef enum
+    { CLEAR
+    , DECODE
+    , OUTADDR
+    , OUTADDR_SEL0
+    , OUTADDR_SEL1
+    , OUTDATA
+    , OUTDATA_SEL0
+    , OUTDATA_SEL1
+    } CtrlBit;
+
+bit [UROM_BITS-1:0] ctrl;
+urom#(UROM, UIP_BITS, UROM_BITS) urom(uip, ctrl);
+
+bit [1:0] asel;
+assign asel = {ctrl[OUTADDR_SEL1], ctrl[OUTADDR_SEL0]};
+
+bit [1:0] dsel;
+assign dsel = {ctrl[OUTDATA_SEL1], ctrl[OUTDATA_SEL0]};
+
+bit [BUS_BITS-1:0] aout;
+assign aout =
+    (asel == 0) ? a :
+    (asel == 1) ? b :
+    (asel == 2) ? {{(BUS_BITS-UIP_BITS){1'b0}}, new_uip} :
+    {(BUS_BITS){1'bX}};
+
+assign abus = ctrl[OUTADDR] ? aout : {(BUS_BITS){1'bZ}};
+
+bit [BUS_BITS-1:0] dout;
+assign dout =
+    (dsel == 0) ? a :
+    (dsel == 1) ? b :
+    (dsel == 2) ? {{(BUS_BITS-1){1'b0}}, needmore} :
+    {(BUS_BITS){1'bX}};
+
+assign dbus = ctrl[OUTDATA] ? dout : {(BUS_BITS){1'bZ}};
+
+always @(posedge clk) begin
+    if (reset || ctrl[CLEAR]) begin
+        opcode <= 0;
+        a <= 0;
+        b <= 0;
+        needmore <= 1;
+    end else if (ctrl[DECODE]) begin
+        automatic bit m = dbus[7];
+        automatic bit i = dbus[6];
+        automatic bit [1:0] field = dbus[5:4];
+        automatic bit [3:0] shift = dbus[3:0];
+        needmore <= m;
+        if (field == 0) begin
+            opcode <= {i ? ~opcode[OPCODE_BITS-1-4:0] : opcode[OPCODE_BITS-1-4:0], shift};
+        end else if (field == 2) begin
+            a <= {i ? ~a[BUS_BITS-1-4:0] : a[BUS_BITS-1-4:0], shift};
+        end else if (field == 3) begin
+            b <= {i ? ~b[BUS_BITS-1-4:0] : b[BUS_BITS-1-4:0], shift};
+        end
+    end
+end
+endmodule
diff --git a/sim/main.cpp b/sim/main.cpp
new file mode 100644
index 0000000..ac4befa
--- /dev/null
+++ b/sim/main.cpp
@@ -0,0 +1,61 @@
+#include <cstdint>
+#include <iostream>
+#include <verilated.h>
+#include <verilated_vcd_c.h>
+
+#include "Vtop.h"
+
+std::uint64_t phases = 0;
+
+double sc_time_stamp()
+{
+    return (double)phases / 2;
+}
+
+int main(int argc, const char *argv[])
+{
+    Verilated::commandArgs(argc, argv);
+
+    Verilated::traceEverOn(true);
+    VerilatedVcdC vcd;
+
+    Vtop top;
+    top.trace(&vcd, 100 /* levels of hierarchy */);
+
+    vcd.set_time_unit("ns");
+    vcd.set_time_resolution("ns");
+    vcd.open("build/out.vcd");
+
+    std::cout << "*** RESET SEQUENCE ***\n";
+
+    top.clk = 0;
+    top.reset = 1;
+    top.eval();
+    vcd.dump(++phases);
+
+    top.clk = 1;
+    top.eval();
+    vcd.dump(++phases);
+
+    top.clk = 0;
+    top.reset = 0;
+    top.eval();
+    vcd.dump(++phases);
+
+    std::cout << "*** MAIN LOOP ***\n";
+
+    for (unsigned int i = 0; i < 10000 && !Verilated::gotFinish(); ++i) {
+        top.clk = 1;
+        top.eval();
+        vcd.dump(++phases);
+        top.clk = 0;
+        top.eval();
+        vcd.dump(++phases);
+    }
+
+    std::cout << "\n";
+
+    vcd.close();
+
+    return 0;
+}
diff --git a/sim/memory.sv b/sim/memory.sv
new file mode 100644
index 0000000..0eb1233
--- /dev/null
+++ b/sim/memory.sv
@@ -0,0 +1,35 @@
+module memory
+    #(  parameter   UROM        = "<no file specified>"
+    ,   parameter   UIP_BITS    = 15
+    ,   parameter   UROM_BITS   = 8
+    ,   parameter   BUS_BITS    = 16
+    ,   parameter   IMAGE       = "<no file specified>"
+    ,   parameter   BYTE_BITS   = 8
+    )
+    (   input   bit                 clk
+    ,   input   bit                 reset
+    ,   input   bit [UIP_BITS-1:0]  uip
+    ,   inout   bit [BUS_BITS-1:0]  abus
+    ,   inout   bit [BUS_BITS-1:0]  dbus
+    );
+
+bit [BYTE_BITS-1:0] storage [0:(1<<BUS_BITS)-1];
+initial $readmemh(IMAGE, storage);
+
+typedef enum
+    { STORE
+    , OUTDATA
+    } CtrlBit;
+
+bit [UROM_BITS-1:0] ctrl;
+urom#(UROM, UIP_BITS, UROM_BITS) urom(uip, ctrl);
+
+assign dbus = ctrl[OUTDATA] ? {{(BUS_BITS-BYTE_BITS){1'b0}}, storage[abus]} : {(BUS_BITS){1'bZ}};
+
+always @(posedge clk) begin
+    if (ctrl[STORE]) begin
+        storage[abus] <= dbus[BYTE_BITS-1:0];
+    end
+end
+
+endmodule
diff --git a/sim/pc.sv b/sim/pc.sv
new file mode 100644
index 0000000..1a3aaee
--- /dev/null
+++ b/sim/pc.sv
@@ -0,0 +1,36 @@
+module pc
+    #(  parameter   UROM        = "<no file specified>"
+    ,   parameter   UIP_BITS    = 15
+    ,   parameter   UROM_BITS   = 8
+    ,   parameter   BUS_BITS    = 16
+    ,   parameter   RESET       = 0
+    )
+    (   input   bit                 clk
+    ,   input   bit                 reset
+    ,   input   bit [UIP_BITS-1:0]  uip
+    ,   inout   bit [BUS_BITS-1:0]  abus
+    ,   inout   bit [BUS_BITS-1:0]  dbus
+    );
+
+bit [BUS_BITS-1:0] addr;
+
+typedef enum
+    { LOAD
+    , INCREMENT
+    , OUTADDR
+    } CtrlBit;
+
+bit [UROM_BITS-1:0] ctrl;
+urom#(UROM, UIP_BITS, UROM_BITS) urom(uip, ctrl);
+
+assign abus = ctrl[OUTADDR] ? addr : {(BUS_BITS){1'bZ}};
+
+always @(posedge clk) begin
+    if (reset) begin
+        addr <= RESET;
+    end else begin
+        addr <= (ctrl[LOAD] ? abus : addr) + (ctrl[INCREMENT] ? 1 : 0);
+    end
+end
+
+endmodule
diff --git a/sim/rf.sv b/sim/rf.sv
new file mode 100644
index 0000000..37502ce
--- /dev/null
+++ b/sim/rf.sv
@@ -0,0 +1,39 @@
+module rf
+    #(  parameter   UROM        = "<no file specified>"
+    ,   parameter   UIP_BITS    = 15
+    ,   parameter   UROM_BITS   = 8
+    ,   parameter   BUS_BITS    = 16
+    ,   parameter   NAME_BITS   = 3
+    )
+    (   input   bit                 clk
+    ,   input   bit                 reset
+    ,   input   bit [UIP_BITS-1:0]  uip
+    ,   inout   bit [BUS_BITS-1:0]  abus
+    ,   inout   bit [BUS_BITS-1:0]  dbus
+    );
+
+bit [BUS_BITS-1:0] storage [0:(1<<NAME_BITS)-1];
+
+typedef enum
+    { STORE
+    , RESET
+    , OUTDATA
+    } CtrlBit;
+
+bit [UROM_BITS-1:0] ctrl;
+urom#(UROM, UIP_BITS, UROM_BITS) urom(uip, ctrl);
+
+assign dbus = ctrl[OUTDATA] ? storage[abus[NAME_BITS-1:0]] : {(BUS_BITS){1'bZ}};
+
+always @(posedge clk) begin
+    if (reset || ctrl[RESET]) begin
+        for (int i = 0; i < (1 << NAME_BITS); ++i)
+            storage[i] <= 0;
+    end else begin
+        if (ctrl[STORE]) begin
+            storage[abus[NAME_BITS-1:0]] <= dbus;
+        end
+    end
+end
+
+endmodule
diff --git a/sim/tmp.sv b/sim/tmp.sv
new file mode 100644
index 0000000..61e35f7
--- /dev/null
+++ b/sim/tmp.sv
@@ -0,0 +1,41 @@
+module tmp
+    #(  parameter   UROM        = "<no file specified>"
+    ,   parameter   UIP_BITS    = 15
+    ,   parameter   UROM_BITS   = 8
+    ,   parameter   BUS_BITS    = 16
+    )
+    (   input   bit                 clk
+    ,   input   bit                 reset
+    ,   input   bit [UIP_BITS-1:0]  uip
+    ,   inout   bit [BUS_BITS-1:0]  abus
+    ,   inout   bit [BUS_BITS-1:0]  dbus
+    );
+
+bit [BUS_BITS-1:0] x;
+
+typedef enum
+    { LOAD
+    , LOAD_SEL0
+    , OUTADDR
+    , OUTDATA
+    } CtrlBit;
+
+bit [UROM_BITS-1:0] ctrl;
+urom#(UROM, UIP_BITS, UROM_BITS) urom(uip, ctrl);
+
+bit [0:0] sel;
+assign sel = {ctrl[LOAD_SEL0]};
+
+assign abus = ctrl[OUTADDR] ? x : {(BUS_BITS){1'bZ}};
+assign dbus = ctrl[OUTDATA] ? x : {(BUS_BITS){1'bZ}};
+
+always @(posedge clk) begin
+    if (ctrl[LOAD]) begin
+        x <=
+            (sel == 0) ? dbus :
+            (sel == 1) ? abus :
+            {(BUS_BITS){1'bX}};
+    end
+end
+
+endmodule
diff --git a/sim/top.sv b/sim/top.sv
new file mode 100644
index 0000000..6773739
--- /dev/null
+++ b/sim/top.sv
@@ -0,0 +1,27 @@
+module top
+    #(  parameter   UIP_BITS    = 15
+    ,   parameter   UROM_BITS   = 8
+    ,   parameter   BUS_BITS    = 16
+    ,   parameter   MEM_BITS    = 8
+    )
+    (   input   bit clk     // verilator public
+    ,   input   bit reset   // verilator public
+    );
+
+bit [UIP_BITS-1:0] uip;
+bit [BUS_BITS-1:0] abus;
+bit [BUS_BITS-1:0] dbus;
+
+alu     #("../out/alu.bin",     UIP_BITS, UROM_BITS, BUS_BITS) alu(clk, reset, uip, abus, dbus);
+control #("../out/control.bin", UIP_BITS, UROM_BITS, BUS_BITS, "../out/consts.0.bin", "../out/consts.1.bin", 'h7ff8) control(clk, reset, uip, abus, dbus);
+decode  #("../out/decode.bin",  UIP_BITS, UROM_BITS, BUS_BITS, 12) decode(clk, reset, uip, abus, dbus);
+memory  #("../out/memory.bin",  UIP_BITS, UROM_BITS, BUS_BITS, "../out/image.hex", MEM_BITS) memory(clk, reset, uip, abus, dbus);
+pc      #("../out/pc.bin",      UIP_BITS, UROM_BITS, BUS_BITS, 0) pc(clk, reset, uip, abus, dbus);
+rf      #("../out/rf.bin",      UIP_BITS, UROM_BITS, BUS_BITS, 3) rf(clk, reset, uip, abus, dbus);
+tmp     #("../out/tmp0.bin",    UIP_BITS, UROM_BITS, BUS_BITS) tmp0(clk, reset, uip, abus, dbus);
+tmp     #("../out/tmp1.bin",    UIP_BITS, UROM_BITS, BUS_BITS) tmp1(clk, reset, uip, abus, dbus);
+uart    #("../out/uart.bin",    UIP_BITS, UROM_BITS, BUS_BITS) uart(clk, reset, uip, abus, dbus);
+
+//always @(negedge clk) $display("pc=%x uip=%x abus=%x dbus=%x tmp0=%x tmp1=%x alu=%x regs=%x:%x:%x:...:%x", pc.addr, uip, abus, dbus, tmp0.x, tmp1.x, alu.x, rf.storage[0], rf.storage[1], rf.storage[2], rf.storage[7]);
+
+endmodule
diff --git a/sim/uart.sv b/sim/uart.sv
new file mode 100644
index 0000000..3b434da
--- /dev/null
+++ b/sim/uart.sv
@@ -0,0 +1,47 @@
+module uart
+    #(  parameter   UROM        = "<no file specified>"
+    ,   parameter   UIP_BITS    = 15
+    ,   parameter   UROM_BITS   = 8
+    ,   parameter   BUS_BITS    = 16
+    )
+    (   input   bit                 clk
+    ,   input   bit                 reset
+    ,   input   bit [UIP_BITS-1:0]  uip
+    ,   inout   bit [BUS_BITS-1:0]  abus
+    ,   inout   bit [BUS_BITS-1:0]  dbus
+    );
+
+bit txfull;
+bit rxempty;
+
+assign txfull = 0;
+assign rxempty = 0;
+
+typedef enum
+    { TX
+    , RX
+    , OUTDATA
+    , OUTDATA_SEL0
+    } CtrlBit;
+
+bit [UROM_BITS-1:0] ctrl;
+urom#(UROM, UIP_BITS, UROM_BITS) urom(uip, ctrl);
+
+bit [0:0] sel;
+assign sel = {ctrl[OUTDATA_SEL0]};
+
+bit [BUS_BITS-1:0] dout;
+assign dout =
+    (ctrl[RX]) ? {(BUS_BITS){1'b1}} :
+    (sel == 0) ? {{(BUS_BITS-1){1'b0}}, txfull} :
+    (sel == 1) ? {{(BUS_BITS-1){1'b0}}, rxempty} :
+    {(BUS_BITS){1'bX}};
+
+assign dbus = ctrl[OUTDATA] ? dout : {(BUS_BITS){1'bZ}};
+
+always @(posedge clk) begin
+    if (ctrl[TX])
+        $display("tx %x", dbus[7:0]);
+end
+
+endmodule
diff --git a/sim/urom.sv b/sim/urom.sv
new file mode 100644
index 0000000..e88f6d7
--- /dev/null
+++ b/sim/urom.sv
@@ -0,0 +1,19 @@
+module urom
+    #(  parameter   UROM        = "<no file specified>"
+    ,   parameter   ADDR_BITS   = 15
+    ,   parameter   DATA_BITS   = 8
+    )
+    (   input   bit [ADDR_BITS-1:0] addr
+    ,   output  bit [DATA_BITS-1:0] data
+    );
+
+bit [DATA_BITS-1:0] storage [0:(1<<ADDR_BITS)-1];
+initial begin
+    automatic int fh;
+    fh = $fopen(UROM, "rb");
+    $fread(storage, fh);
+end
+
+assign data = storage[addr];
+
+endmodule