endian swapper

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David Harris 2022-05-08 06:51:50 +00:00
parent 4f1b0fdc64
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///////////////////////////////////////////
// bigendianswap.sv
//
// Written: David_Harris@hmc.edu 7 May 2022
// Modified:
//
// Purpose: Swap byte order for Big-Endian accesses
//
// A component of the Wally configurable RISC-V project.
//
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// MIT LICENSE
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.
////////////////////////////////////////////////////////////////////////////////////////////////
`include "wally-config.vh"
module bigendianswap (
input logic BigEndianM,
input logic [`XLEN-1:0] a,
output logic [`XLEN-1:0] y);
if(`XLEN == 64) begin
always_comb
if (BigEndianM) begin // swap endianness
y[63:56] = a[7:0];
y[55:48] = a[15:8];
y[47:40] = a[23:16];
y[39:32] = a[31:24];
y[31:24] = a[39:32];
y[23:16] = a[47:40];
y[15:8] = a[55:48];
y[7:0] = a[63:56];
end else y = a;
end else begin
always_comb
if (BigEndianM) begin
y[31:24] = a[7:0];
y[23:16] = a[15:8];
y[15:8] = a[23:16];
y[7:0] = a[31:24];
end else y = a;
end
endmodule