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removed old shifter

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This commit is contained in:
Kevin Kim 2023-02-24 17:33:47 -08:00
parent 9d119d1312
commit c7050ada78
3 changed files with 35 additions and 175 deletions
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2
src/ieu/alu.sv
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@ -85,7 +85,7 @@ module alu #(parameter WIDTH=32) (
// Pre-Shift Mux
always_comb
case (Funct3[2:1] & {2{BSelect[3]}})
2'b00: CondShiftA = shA[63:0];
2'b00: CondShiftA = shA[WIDTH-1:0];
2'b01: CondShiftA = {shA[WIDTH-2:0],{1'b0}}; // sh1add
2'b10: CondShiftA = {shA[WIDTH-3:0],{2'b00}}; // sh2add
2'b11: CondShiftA = {shA[WIDTH-4:0],{3'b000}}; // sh3add

111
src/ieu/shifter.sv
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@ -1,7 +1,7 @@
///////////////////////////////////////////
// shifter.sv
//
// Written: David_Harris@hmc.edu, Sarah.Harris@unlv.edu, kekim@hmc.edu
// Written: David_Harris@hmc.edu, Sarah.Harris@unlv.edu, Kevin Kim <kekim@hmc.edu>
// Created: 9 January 2021
// Modified: 6 February 2023
//
@ -29,111 +29,56 @@
`include "wally-config.vh"
module shifter (
input logic [`XLEN-1:0] A, // Source
module shifternew (
input logic [`XLEN:0] shA, // shift Source
input logic [`XLEN-1:0] rotA, // rotate source
input logic [`LOG_XLEN-1:0] Amt, // Shift amount
input logic Right, Arith, W64, Rotate, // Shift right, arithmetic, RV64 W-type shift
input logic Right, Rotate, W64, // Shift right, rotate signals
output logic [`XLEN-1:0] Y); // Shifted result
logic [2*`XLEN-2:0] z, zshift; // Input to funnel shifter, shifted amount before truncated to 32 or 64 bits
logic [`LOG_XLEN-1:0] amttrunc, offset, CondOffsetTrunc; // Shift amount adjusted for RV64, right-shift amount
logic [`LOG_XLEN-1:0] amttrunc, offset; // Shift amount adjusted for RV64, right-shift amount
// Handle left and right shifts with a funnel shifter.
// For RV32, only 32-bit shifts are needed.
// For RV64, 32- and 64-bit shifts are needed, with sign extension.
/*
// Funnel shifter input (see CMOS VLSI Design 4e Section 11.8.1, note Table 11.11 shift types wrong)
if (`XLEN==32) begin:shifter // RV32
if (`ZBB_SUPPORTED) begin: rotfunnel
if (`XLEN==32) begin // rv32 with rotates
always_comb // funnel mux
if (Right)
if (Arith) z = {{31{A[31]}}, A};
else z = {31'b0, A};
else z = {A, 31'b0};
case({Right, Rotate})
2'b00: z = {shA[31:0], 31'b0};
2'b01: z = {rotA,rotA[31:1]};
2'b10: z = {{31{shA[32]}}, shA[31:0]};
2'b11: z = {rotA[30:0],rotA};
endcase
assign amttrunc = Amt; // shift amount
end else begin:shifter // RV64
end else begin // rv64 with rotates
always_comb // funnel mux
if (W64) begin // 32-bit shifts
if (Right)
if (Arith) z = {64'b0, {31{A[31]}}, A[31:0]};
else z = {95'b0, A[31:0]};
else z = {32'b0, A[31:0], 63'b0};
end else begin
if (Right)
if (Arith) z = {{63{A[63]}}, A};
else z = {63'b0, A};
else z = {A, 63'b0};
end
case ({Right, Rotate})
2'b00: z = {shA[63:0],{63'b0}};
2'b01: z = {rotA, rotA[63:1]};
2'b10: z = {{63{shA[64]}},shA[63:0]};
2'b11: z = {rotA[62:0],rotA[63:0]};
endcase
assign amttrunc = W64 ? {1'b0, Amt[4:0]} : Amt; // 32- or 64-bit shift
end
*/
if (`ZBB_SUPPORTED) begin: rotFunnel // HANDLES ROTATE
end else begin: norotfunnel
if (`XLEN==32) begin:shifter // RV32
always_comb // funnel mux
if (Right)
if (Rotate) z = {A[30:0], A[31:0]}; //ror (rv32)
else
if (Arith) z = {{31{A[31]}}, A};
else z = {31'b0, A};
else
if (Rotate) z = {A[31:0], A[31:1]}; //rol (rv32)
else z = {A, 31'b0};
if (Right) z = {{31{shA[32]}}, shA[31:0]};
else z = {shA[31:0], 31'b0};
assign amttrunc = Amt; // shift amount
end else begin:shifter // RV64
always_comb // funnel mux
if (W64) begin // 32-bit shifts
if (Right)
if (Rotate) z = {{64'b0},A[30:0],A[31:0]}; //rorw
else
if (Arith) z = {64'b0, {31{A[31]}}, A[31:0]};
else z = {95'b0, A[31:0]};
else
if (Rotate) z = {{64'b0},A[31:0],A[31:1]}; //rolw
else z = {32'b0, A[31:0], 63'b0};
end else begin
if (Right)
if (Rotate) z = {A[62:0], A[63:0]}; //ror
else
if (Arith) z = {{63{A[63]}}, A};
else z = {63'b0, A};
else
if (Rotate) z = {A[63:0], A[63:1]}; //rol
else z = {A, 63'b0};
end
assign amttrunc = W64 ? {1'b0, Amt[4:0]} : Amt; // 32- or 64-bit shift
end
end else begin: norotFunnel
if (`XLEN==32) begin:shifter // RV32
always_comb // funnel mux
if (Right)
if (Arith) z = {{31{A[31]}}, A};
else z = {31'b0, A};
else z = {A, 31'b0};
assign amttrunc = Amt; // shift amount
end else begin:shifter // RV64
always_comb // funnel mux
if (W64) begin // 32-bit shifts
if (Right)
if (Arith) z = {64'b0, {31{A[31]}}, A[31:0]};
else z = {95'b0, A[31:0]};
else z = {32'b0, A[31:0], 63'b0};
end else begin
if (Right)
if (Arith) z = {{63{A[63]}}, A};
else z = {63'b0, A};
else z = {A, 63'b0};
end
if (Right) z = {{63{shA[64]}},shA[63:0]};
else z = {shA[63:0],{63'b0}};
assign amttrunc = W64 ? {1'b0, Amt[4:0]} : Amt; // 32- or 64-bit shift
end
end
// Opposite offset for right shifts
assign offset = Right ? amttrunc : ~amttrunc;
if (`XLEN == 64) assign CondOffsetTrunc = (W64 & Rotate) ? {{1'b0}, offset[4:0]} : offset;
else assign CondOffsetTrunc = offset;
// Funnel operation
assign zshift = z >> CondOffsetTrunc;
assign zshift = z >> offset;
assign Y = zshift[`XLEN-1:0];
endmodule

85
src/ieu/shifternew.sv
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@ -1,85 +0,0 @@
///////////////////////////////////////////
// shifter.sv
//
// Written: David_Harris@hmc.edu, Sarah.Harris@unlv.edu, kekim@hmc.edu
// Created: 9 January 2021
// Modified: 6 February 2023
//
// Purpose: RISC-V 32/64 bit shifter
//
// Documentation: RISC-V System on Chip Design Chapter 4 (Figure 4.5, Table 4.3)
//
// A component of the CORE-V-WALLY configurable RISC-V project.
//
// Copyright (C) 2021-23 Harvey Mudd College & Oklahoma State University
//
// SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
//
// Licensed under the Solderpad Hardware License v 2.1 (the “License”); you may not use this file
// except in compliance with the License, or, at your option, the Apache License version 2.0. You
// may obtain a copy of the License at
//
// https://solderpad.org/licenses/SHL-2.1/
//
// Unless required by applicable law or agreed to in writing, any work distributed under the
// License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
// either express or implied. See the License for the specific language governing permissions
// and limitations under the License.
////////////////////////////////////////////////////////////////////////////////////////////////
`include "wally-config.vh"
module shifternew (
input logic [`XLEN:0] shA, // shift Source
input logic [`XLEN-1:0] rotA, // rotate source
input logic [`LOG_XLEN-1:0] Amt, // Shift amount
input logic Right, Rotate, W64, // Shift right, rotate signals
output logic [`XLEN-1:0] Y); // Shifted result
logic [2*`XLEN-2:0] z, zshift; // Input to funnel shifter, shifted amount before truncated to 32 or 64 bits
logic [`LOG_XLEN-1:0] amttrunc, offset; // Shift amount adjusted for RV64, right-shift amount
if (`ZBB_SUPPORTED) begin: rotfunnel
if (`XLEN==32) begin // rv32 with rotates
always_comb // funnel mux
case({Right, Rotate})
2'b00: z = {shA[31:0], 31'b0};
2'b01: z = {rotA,rotA[31:1]};
2'b10: z = {{31{shA[32]}}, shA[31:0]};
2'b11: z = {rotA[30:0],rotA};
endcase
assign amttrunc = Amt; // shift amount
end else begin // rv64 with rotates
always_comb // funnel mux
case ({Right, Rotate})
2'b00: z = {shA[63:0],{63'b0}};
2'b01: z = {rotA, rotA[63:1]};
2'b10: z = {{63{shA[64]}},shA[63:0]};
2'b11: z = {rotA[62:0],rotA[63:0]};
endcase
assign amttrunc = W64 ? {1'b0, Amt[4:0]} : Amt; // 32- or 64-bit shift
end
end else begin: norotfunnel
if (`XLEN==32) begin:shifter // RV32
always_comb // funnel mux
if (Right) z = {{31{shA[32]}}, shA[31:0]};
else z = {shA[31:0], 31'b0};
assign amttrunc = Amt; // shift amount
end else begin:shifter // RV64
always_comb // funnel mux
if (Right) z = {{63{shA[64]}},shA[63:0]};
else z = {shA[63:0],{63'b0}};
assign amttrunc = W64 ? {1'b0, Amt[4:0]} : Amt; // 32- or 64-bit shift
end
end
// Opposite offset for right shifts
assign offset = Right ? amttrunc : ~amttrunc;
// Funnel operation
assign zshift = z >> offset;
assign Y = zshift[`XLEN-1:0];
endmodule