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//////////////////////////////////////////////////////////////////////
////                                                              ////
////  OR1200's register file read operands mux                    ////
////                                                              ////
////  This file is part of the OpenRISC 1200 project              ////
////  http://www.opencores.org/cores/or1k/                        ////
////                                                              ////
////  Description                                                 ////
////  Mux for two register file read operands.                    ////
////                                                              ////
////  To Do:                                                      ////
////   - make it smaller and faster                               ////
////                                                              ////
////  Author(s):                                                  ////
////      - Damjan Lampret, lampret@opencores.org                 ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
////                                                              ////
//// Copyright (C) 2000 Authors and OPENCORES.ORG                 ////
////                                                              ////
//// This source file may be used and distributed without         ////
//// restriction provided that this copyright statement is not    ////
//// removed from the file and that any derivative work contains  ////
//// the original copyright notice and the associated disclaimer. ////
////                                                              ////
//// This source file is free software; you can redistribute it   ////
//// and/or modify it under the terms of the GNU Lesser General   ////
//// Public License as published by the Free Software Foundation; ////
//// either version 2.1 of the License, or (at your option) any   ////
//// later version.                                               ////
////                                                              ////
//// This source is distributed in the hope that it will be       ////
//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////
//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////
//// PURPOSE.  See the GNU Lesser General Public License for more ////
//// details.                                                     ////
////                                                              ////
//// You should have received a copy of the GNU Lesser General    ////
//// Public License along with this source; if not, download it   ////
//// from http://www.opencores.org/lgpl.shtml                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
//
// CVS Revision History
//
// $Log: not supported by cvs2svn $
// Revision 1.1  2002/01/03 08:16:15  lampret
// New prefixes for RTL files, prefixed module names. Updated cache controllers and MMUs.
//
// Revision 1.9  2001/11/12 01:45:40  lampret
// Moved flag bit into SR. Changed RF enable from constant enable to dynamic enable for read ports.
//
// Revision 1.8  2001/10/21 17:57:16  lampret
// Removed params from generic_XX.v. Added translate_off/on in sprs.v and id.v. Removed spr_addr from dc.v and ic.v. Fixed CR+LF.
//
// Revision 1.7  2001/10/14 13:12:09  lampret
// MP3 version.
//
// Revision 1.1.1.1  2001/10/06 10:18:36  igorm
// no message
//
// Revision 1.2  2001/08/09 13:39:33  lampret
// Major clean-up.
//
// Revision 1.1  2001/07/20 00:46:05  lampret
// Development version of RTL. Libraries are missing.
//
//
 
// synopsys translate_off
`include "timescale.v"
// synopsys translate_on
`include "or1200_defines.v"
 
module or1200_operandmuxes(
        // Clock and reset
        clk, rst,
 
        // Internal i/f
        id_freeze, ex_freeze, rf_dataa, rf_datab, ex_forw, wb_forw,
        simm, sel_a, sel_b, operand_a, operand_b, muxed_b
);
 
parameter width = `OR1200_OPERAND_WIDTH;
 
//
// I/O
//
input                           clk;
input                           rst;
input                           id_freeze;
input                           ex_freeze;
input   [width-1:0]              rf_dataa;
input   [width-1:0]              rf_datab;
input   [width-1:0]              ex_forw;
input   [width-1:0]              wb_forw;
input   [width-1:0]              simm;
input   [`OR1200_SEL_WIDTH-1:0]  sel_a;
input   [`OR1200_SEL_WIDTH-1:0]  sel_b;
output  [width-1:0]              operand_a;
output  [width-1:0]              operand_b;
output  [width-1:0]              muxed_b;
 
//
// Internal wires and regs
//
reg     [width-1:0]              operand_a;
reg     [width-1:0]              operand_b;
reg     [width-1:0]              muxed_a;
reg     [width-1:0]              muxed_b;
reg                             saved_a;
reg                             saved_b;
 
//
// Operand A register
//
always @(posedge clk or posedge rst) begin
        if (rst) begin
                operand_a <= #1 32'd0;
                saved_a <= #1 1'b0;
        end else if (!ex_freeze && id_freeze && !saved_a) begin
                operand_a <= #1 muxed_a;
                saved_a <= #1 1'b1;
        end else if (!ex_freeze && !saved_a) begin
                operand_a <= #1 muxed_a;
        end else if (!ex_freeze && !id_freeze)
                saved_a <= #1 1'b0;
end
 
//
// Operand B register
//
always @(posedge clk or posedge rst) begin
        if (rst) begin
                operand_b <= #1 32'd0;
                saved_b <= #1 1'b0;
        end else if (!ex_freeze && id_freeze && !saved_b) begin
                operand_b <= #1 muxed_b;
                saved_b <= #1 1'b1;
        end else if (!ex_freeze && !saved_b) begin
                operand_b <= #1 muxed_b;
        end else if (!ex_freeze && !id_freeze)
                saved_b <= #1 1'b0;
end
 
//
// Forwarding logic for operand A register
//
always @(ex_forw or wb_forw or rf_dataa or sel_a) begin
`ifdef OR1200_ADDITIONAL_SYNOPSYS_DIRECTIVES
        casex (sel_a)   // synopsys parallel_case infer_mux
`else
        casex (sel_a)   // synopsys parallel_case
`endif
                `OR1200_SEL_EX_FORW:
                        muxed_a = ex_forw;
                `OR1200_SEL_WB_FORW:
                        muxed_a = wb_forw;
                default:
                        muxed_a = rf_dataa;
        endcase
end
 
//
// Forwarding logic for operand B register
//
always @(simm or ex_forw or wb_forw or rf_datab or sel_b) begin
`ifdef OR1200_ADDITIONAL_SYNOPSYS_DIRECTIVES
        casex (sel_b)   // synopsys parallel_case infer_mux
`else
        casex (sel_b)   // synopsys parallel_case
`endif
                `OR1200_SEL_IMM:
                        muxed_b = simm;
                `OR1200_SEL_EX_FORW:
                        muxed_b = ex_forw;
                `OR1200_SEL_WB_FORW:
                        muxed_b = wb_forw;
                default:
                        muxed_b = rf_datab;
        endcase
end
 
endmodule

Line No.	Rev	Author	Line
1	504	lampret	`//////////////////////////////////////////////////////////////////////`
2			`//// ////`
3			`//// OR1200's register file read operands mux ////`
4			`//// ////`
5			`//// This file is part of the OpenRISC 1200 project ////`
6			`//// http://www.opencores.org/cores/or1k/ ////`
7			`//// ////`
8			`//// Description ////`
9			`//// Mux for two register file read operands. ////`
10			`//// ////`
11			`//// To Do: ////`
12			`//// - make it smaller and faster ////`
13			`//// ////`
14			`//// Author(s): ////`
15			`//// - Damjan Lampret, lampret@opencores.org ////`
16			`//// ////`
17			`//////////////////////////////////////////////////////////////////////`
18			`//// ////`
19			`//// Copyright (C) 2000 Authors and OPENCORES.ORG ////`
20			`//// ////`
21			`//// This source file may be used and distributed without ////`
22			`//// restriction provided that this copyright statement is not ////`
23			`//// removed from the file and that any derivative work contains ////`
24			`//// the original copyright notice and the associated disclaimer. ////`
25			`//// ////`
26			`//// This source file is free software; you can redistribute it ////`
27			`//// and/or modify it under the terms of the GNU Lesser General ////`
28			`//// Public License as published by the Free Software Foundation; ////`
29			`//// either version 2.1 of the License, or (at your option) any ////`
30			`//// later version. ////`
31			`//// ////`
32			`//// This source is distributed in the hope that it will be ////`
33			`//// useful, but WITHOUT ANY WARRANTY; without even the implied ////`
34			`//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ////`
35			`//// PURPOSE. See the GNU Lesser General Public License for more ////`
36			`//// details. ////`
37			`//// ////`
38			`//// You should have received a copy of the GNU Lesser General ////`
39			`//// Public License along with this source; if not, download it ////`
40			`//// from http://www.opencores.org/lgpl.shtml ////`
41			`//// ////`
42			`//////////////////////////////////////////////////////////////////////`
43			`//`
44			`// CVS Revision History`
45			`//`
46			`// $Log: not supported by cvs2svn $`
47	788	lampret	`// Revision 1.1 2002/01/03 08:16:15 lampret`
48			`// New prefixes for RTL files, prefixed module names. Updated cache controllers and MMUs.`
49			`//`
50	504	lampret	`// Revision 1.9 2001/11/12 01:45:40 lampret`
51			`// Moved flag bit into SR. Changed RF enable from constant enable to dynamic enable for read ports.`
52			`//`
53			`// Revision 1.8 2001/10/21 17:57:16 lampret`
54			`// Removed params from generic_XX.v. Added translate_off/on in sprs.v and id.v. Removed spr_addr from dc.v and ic.v. Fixed CR+LF.`
55			`//`
56			`// Revision 1.7 2001/10/14 13:12:09 lampret`
57			`// MP3 version.`
58			`//`
59			`// Revision 1.1.1.1 2001/10/06 10:18:36 igorm`
60			`// no message`
61			`//`
62			`// Revision 1.2 2001/08/09 13:39:33 lampret`
63			`// Major clean-up.`
64			`//`
65			`// Revision 1.1 2001/07/20 00:46:05 lampret`
66			`// Development version of RTL. Libraries are missing.`
67			`//`
68			`//`
69
70			`// synopsys translate_off`
71			`include "timescale.v"
72			`// synopsys translate_on`
73			`include "or1200_defines.v"
74
75			`module or1200_operandmuxes(`
76			`// Clock and reset`
77			`clk, rst,`
78
79			`// Internal i/f`
80			`id_freeze, ex_freeze, rf_dataa, rf_datab, ex_forw, wb_forw,`
81			`simm, sel_a, sel_b, operand_a, operand_b, muxed_b`
82			`);`
83
84			parameter width = `OR1200_OPERAND_WIDTH;
85
86			`//`
87			`// I/O`
88			`//`
89			`input clk;`
90			`input rst;`
91			`input id_freeze;`
92			`input ex_freeze;`
93			`input [width-1:0] rf_dataa;`
94			`input [width-1:0] rf_datab;`
95			`input [width-1:0] ex_forw;`
96			`input [width-1:0] wb_forw;`
97			`input [width-1:0] simm;`
98			input [`OR1200_SEL_WIDTH-1:0] sel_a;
99			input [`OR1200_SEL_WIDTH-1:0] sel_b;
100			`output [width-1:0] operand_a;`
101			`output [width-1:0] operand_b;`
102			`output [width-1:0] muxed_b;`
103
104			`//`
105			`// Internal wires and regs`
106			`//`
107			`reg [width-1:0] operand_a;`
108			`reg [width-1:0] operand_b;`
109			`reg [width-1:0] muxed_a;`
110			`reg [width-1:0] muxed_b;`
111			`reg saved_a;`
112			`reg saved_b;`
113
114			`//`
115			`// Operand A register`
116			`//`
117			`always @(posedge clk or posedge rst) begin`
118			`if (rst) begin`
119			`operand_a <= #1 32'd0;`
120			`saved_a <= #1 1'b0;`
121			`end else if (!ex_freeze && id_freeze && !saved_a) begin`
122			`operand_a <= #1 muxed_a;`
123			`saved_a <= #1 1'b1;`
124			`end else if (!ex_freeze && !saved_a) begin`
125			`operand_a <= #1 muxed_a;`
126			`end else if (!ex_freeze && !id_freeze)`
127			`saved_a <= #1 1'b0;`
128			`end`
129
130			`//`
131			`// Operand B register`
132			`//`
133			`always @(posedge clk or posedge rst) begin`
134			`if (rst) begin`
135			`operand_b <= #1 32'd0;`
136			`saved_b <= #1 1'b0;`
137			`end else if (!ex_freeze && id_freeze && !saved_b) begin`
138			`operand_b <= #1 muxed_b;`
139			`saved_b <= #1 1'b1;`
140			`end else if (!ex_freeze && !saved_b) begin`
141			`operand_b <= #1 muxed_b;`
142			`end else if (!ex_freeze && !id_freeze)`
143			`saved_b <= #1 1'b0;`
144			`end`
145
146			`//`
147			`// Forwarding logic for operand A register`
148			`//`
149			`always @(ex_forw or wb_forw or rf_dataa or sel_a) begin`
150	788	lampret	`ifdef OR1200_ADDITIONAL_SYNOPSYS_DIRECTIVES
151			`casex (sel_a) // synopsys parallel_case infer_mux`
152			`else
153			`casex (sel_a) // synopsys parallel_case`
154			`endif
155	504	lampret	`OR1200_SEL_EX_FORW:
156			`muxed_a = ex_forw;`
157			`OR1200_SEL_WB_FORW:
158			`muxed_a = wb_forw;`
159			`default:`
160			`muxed_a = rf_dataa;`
161			`endcase`
162			`end`
163
164			`//`
165			`// Forwarding logic for operand B register`
166			`//`
167			`always @(simm or ex_forw or wb_forw or rf_datab or sel_b) begin`
168	788	lampret	`ifdef OR1200_ADDITIONAL_SYNOPSYS_DIRECTIVES
169			`casex (sel_b) // synopsys parallel_case infer_mux`
170			`else
171			`casex (sel_b) // synopsys parallel_case`
172			`endif
173	504	lampret	`OR1200_SEL_IMM:
174			`muxed_b = simm;`
175			`OR1200_SEL_EX_FORW:
176			`muxed_b = ex_forw;`
177			`OR1200_SEL_WB_FORW:
178			`muxed_b = wb_forw;`
179			`default:`
180			`muxed_b = rf_datab;`
181			`endcase`
182			`end`
183
184			`endmodule`

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