From 60e1775b874015a3451e4bde10a8eb30701b1165 Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Tue, 6 Jul 2021 09:44:36 -0700
Subject: Initial commit.

---
 sim/uart.sv | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 sim/uart.sv

(limited to 'sim/uart.sv')

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
-- 
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