fpga: rfnoc: Add 4 KiB boundary check to sim_axi_ram

Adding a check for bursts that cross the 4 KiB boundary to the AXI4
memory model. Crossing a 4 KiB boundary is not allowed by AXI4.

1 files changed, 12 insertions, 0 deletions

diff --git a/fpga/usrp3/lib/rfnoc/blocks/rfnoc_block_axi_ram_fifo/sim_axi_ram.sv b/fpga/usrp3/lib/rfnoc/blocks/rfnoc_block_axi_ram_fifo/sim_axi_ram.sv
index ee7ff5df8..efe3c2f30 100644
--- a/fpga/usrp3/lib/rfnoc/blocks/rfnoc_block_axi_ram_fifo/sim_axi_ram.sv
+++ b/fpga/usrp3/lib/rfnoc/blocks/rfnoc_block_axi_ram_fifo/sim_axi_ram.sv
@@ -75,6 +75,10 @@ module sim_axi_ram #(
 
   localparam DEBUG = 0;
 
+  // Define a mask that can be used to tell which 4K window is being addressed
+  localparam [AWIDTH-1:0] MASK_4K = {AWIDTH{1'b1}} << 12;
+
+
   //---------------------------------------------------------------------------
   // Data Types
   //---------------------------------------------------------------------------
@@ -309,6 +313,10 @@ module sim_axi_ram #(
           assert ($cast(burst, s_axi_awburst)) else begin
             $fatal(1, "Invalid AWBURST value");
           end
+          assert ((s_axi_awaddr & MASK_4K) ==
+            ((s_axi_awaddr + (s_axi_awlen+1)*(2**s_axi_awsize) - 1) & MASK_4K)) else begin
+            $fatal(1, "Memory write burst crosses 4 KiB boundary");
+          end
 
           if (DEBUG) begin
             $display("WRITE REQ: id=%X, addr=%X, len=%X, size=%X, burst=%s, %t, %m", 
@@ -362,6 +370,10 @@ module sim_axi_ram #(
           assert ($cast(burst, s_axi_awburst)) else begin
             $fatal(1, "Invalid ARBURST value");
           end
+          assert ((s_axi_araddr & MASK_4K) ==
+            ((s_axi_araddr + (s_axi_arlen+1)*(2**s_axi_arsize) - 1) & MASK_4K)) else begin
+            $fatal(1, "Memory read burst crosses 4 KiB boundary");
+          end
 
           if (DEBUG) begin
             $display("READ REQ:  id=%X, addr=%X, len=%X, size=%X, burst=%s, %t, %m",