From e621d4047b48b4cb5c5a70e23dae845c77235917 Mon Sep 17 00:00:00 2001
From: Byron Lathi <bslathi19@gmail.com>
Date: Mon, 16 Oct 2023 23:38:37 -0700
Subject: [PATCH] Add mapper and testbench

---
 .gitlab-ci.yml                             |  14 +++
 hw/efinix_fpga/simulation/Makefile         |   6 ++
 hw/efinix_fpga/simulation/tbs/mapper_tb.sv | 100 +++++++++++++++++++++
 hw/efinix_fpga/src/mapper.sv               |  40 +++++++++
 4 files changed, 160 insertions(+)
 create mode 100644 hw/efinix_fpga/simulation/tbs/mapper_tb.sv
 create mode 100644 hw/efinix_fpga/src/mapper.sv

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 453baae..20d3054 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -116,3 +116,17 @@ full sim:
   dependencies:
     - build toolchain
 
+mapper sim:
+  tags:
+    - linux
+    - iverilog
+  stage: simulate
+  artifacts:
+    paths:
+      - hw/efinix_fpga/simulation/mapper_tb.vcd
+  script:
+    - source init_env.sh
+    - cd hw/efinix_fpga/simulation
+    - make clean
+    - make mapper_tb
+    - ./mapper_tb
\ No newline at end of file
diff --git a/hw/efinix_fpga/simulation/Makefile b/hw/efinix_fpga/simulation/Makefile
index e59b38c..b349018 100644
--- a/hw/efinix_fpga/simulation/Makefile
+++ b/hw/efinix_fpga/simulation/Makefile
@@ -1,4 +1,5 @@
 SRCS=$(shell find src/ -type f -name "*.*v")
+TBS=$(shell find tbs/ -type f -name "*.*v")
 SRCS+=$(shell find ../ip/ -type f -name "*.*v" -not \( -name "*tmpl*" \))
 SRCS+=$(shell find ../src/ -type f -name "*.*v")
 
@@ -28,6 +29,9 @@ sim: $(TARGET)
 full_sim: $(TARGET) $(SD_IMAGE)
 	vvp $(TARGET) -fst
 
+mapper_tb: $(SRCS) $(TBS)
+	iverilog -g2005-sv $(FLAGS) -s $@ -o $@ $(INC) $(SRCS) $(TBS)
+
 
 $(TARGET): $(INIT_MEM) $(SRCS)
 	iverilog -g2005-sv $(FLAGS) -s $(TOP_MODULE) -o $(TARGET) $(INC) $(SRCS)
@@ -46,3 +50,5 @@ clean:
 	rm -rf $(TARGET)
 	rm -rf $(INIT_MEM)
 	rm -rf $(SD_IMAGE)
+	rm -rf mapper_tb
+	rm -rf mapper_tb.vcd
diff --git a/hw/efinix_fpga/simulation/tbs/mapper_tb.sv b/hw/efinix_fpga/simulation/tbs/mapper_tb.sv
new file mode 100644
index 0000000..ab62128
--- /dev/null
+++ b/hw/efinix_fpga/simulation/tbs/mapper_tb.sv
@@ -0,0 +1,100 @@
+`timescale 1ns/1ps
+
+module mapper_tb();
+
+logic r_clk_cpu;
+
+// clk_cpu
+initial begin
+    r_clk_cpu <= '1;
+    forever begin
+        #125 r_clk_cpu <= ~r_clk_cpu;
+    end
+end
+
+logic reset;
+logic [15:0] addr;
+logic [24:0] map_addr;
+logic [7:0] i_data;
+logic [7:0] o_data;
+logic cs;
+logic rwb;
+
+mapper u_mapper(
+    .i_reset(reset),
+    .i_clk(r_clk_cpu),
+    .i_cs(cs),
+    .i_we(~rwb),
+    .i_data(i_data),
+    .o_data(o_data),
+    .i_cpu_addr(addr),
+    .o_mapped_addr(map_addr)
+);
+
+
+/* These could be made better probably */
+task write_reg(input logic [4:0] _addr, input logic [7:0] _data);
+    @(negedge r_clk_cpu);
+    cs <= '1;
+    addr <= _addr;
+    rwb <= '0;
+    i_data <= '1;
+    @(posedge r_clk_cpu);
+    i_data <= _data;
+    @(negedge r_clk_cpu);
+    cs <= '0;
+    rwb <= '1;
+endtask
+
+task read_reg(input logic [2:0] _addr, output logic [7:0] _data);
+    @(negedge r_clk_cpu);
+    cs <= '1;
+    addr <= _addr;
+    rwb <= '1;
+    i_data <= '1;
+    @(posedge r_clk_cpu);
+    _data <= o_data;
+    @(negedge r_clk_cpu);
+    cs <= '0;
+    rwb <= '1;
+endtask
+
+int errors;
+
+initial begin
+    errors = 0;
+    repeat (5) @(posedge r_clk_cpu);
+    reset = 1;
+    cs = 0;
+    rwb = 1;
+    addr = '0;
+    i_data = '0;
+    repeat (5) @(posedge r_clk_cpu);
+    reset = 0;
+    repeat (5) @(posedge r_clk_cpu);
+
+    write_reg(0, 8'haa);
+    write_reg(1, 8'hbb);
+
+    repeat (5) @(posedge r_clk_cpu);
+
+    assert (u_mapper.mm[0] == 16'hbbaa) else begin
+        $error("mm[0] expected 0xbbaa got 0x%x", u_mapper.mm[0]);
+        errors += 1;
+    end
+
+    if (errors != 0) begin
+        $finish_and_return(-1);
+    end else begin
+        $finish();
+    end
+end
+
+initial
+begin
+    $dumpfile("mapper_tb.vcd");
+    $dumpvars(0,mapper_tb);
+    for (int i = 0; i < 16; i++) $dumpvars(0, u_mapper.mm[i]);
+end
+
+endmodule
diff --git a/hw/efinix_fpga/src/mapper.sv b/hw/efinix_fpga/src/mapper.sv
new file mode 100644
index 0000000..48ac8d3
--- /dev/null
+++ b/hw/efinix_fpga/src/mapper.sv
@@ -0,0 +1,40 @@
+module mapper(
+    input i_reset,
+    input i_clk,
+    input i_cs,
+    input i_we,
+    input [7:0] i_data,
+    output logic [7:0] o_data,
+    input [15:0] i_cpu_addr,
+    output logic [24:0] o_mapped_addr
+);
+
+logic [15:0] mm [16];
+
+logic [31:0] we;
+
+logic [15:0] mm_sel;
+
+always_comb begin
+    we = (i_we << i_cpu_addr[4:0]);
+
+    o_data = mm_sel[8*i_cpu_addr[0] +: 8];
+end
+
+always_ff @(negedge i_clk or posedge i_reset) begin
+    if (i_reset) begin
+        for (int i = 0; i < 16; i++) begin
+            mm[i] <= i;
+        end
+    end
+
+    for (int i = 0; i < 31; i++) begin
+        if (we[i]) begin
+            mm[i/2][(i%2)*8 +: 8] <= i_data;
+        end
+    end
+
+
+end
+
+endmodule