forgot the normshift module

2025-02-11 06:05:49 +00:00 · 2023-01-04 10:48:19 -06:00 · 2023-01-04 10:48:19 -06:00 · 970318f881
commit 970318f881
parent 95a1ddd636
1 changed files with 75 additions and 0 deletions
--- a/pipelined/src/fpu/postproc/normshift.sv
+++ b/pipelined/src/fpu/postproc/normshift.sv
@ -0,0 +1,75 @@
+///////////////////////////////////////////
+// normshift.sv
+//
+// Written: me@KatherineParry.com
+// Modified: 7/5/2022
+//
+// Purpose: normalization shifter
+// 
+// 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"
+
+
+ // convert shift
+    //      fp -> int: |  `XLEN  zeros |     Mantissa      | 0's if nessisary | << CalcExp
+    //          process:
+    //              - start - CalcExp = 1 + XExp - Largest Bias
+    //                  |  `XLEN  zeros     |     Mantissa      | 0's if nessisary |
+    //
+    //              - shift left 1 (1)
+    //                  | `XLEN-1 zeros |bit|     frac      | 0's if nessisary |
+    //                                      . <- binary point
+    //
+    //              - shift left till unbiased exponent is 0 (XExp - Largest Bias)
+    //                  |  0's |     Mantissa      |      0's if nessisary     |
+    //                  |     keep          |
+    //
+    //      fp -> fp:
+    //          - if result is denormalized or underflowed:
+    //              |  `NF-1  zeros   |     Mantissa      | 0's if nessisary | << NF+CalcExp-1
+    //          process:
+    //             - start
+    //                 |     mantissa      | 0's |
+    //
+    //             - shift right by NF-1 (NF-1)
+    //                 |  `NF-1  zeros   |     mantissa      | 0's |
+    //
+    //             - shift left by CalcExp = XExp - Largest bias + new bias
+    //                 |   0's  |     mantissa      |     0's      |
+    //                 |       keep      |
+    //
+    //          - if the input is denormalized:
+    //              |     lzcIn      | 0's if nessisary | << ZeroCnt+1
+    //              - plus 1 to shift out the first 1
+    //
+    //      int -> fp: |     lzcIn      | 0's if nessisary | << ZeroCnt+1
+    //              - plus 1 to shift out the first 1
+
+module normshift(
+    input logic  [`LOGNORMSHIFTSZ-1:0]      ShiftAmt,   // normalization shift count
+    input logic  [`NORMSHIFTSZ-1:0]              ShiftIn,        // is the sum zero
+    output logic [`NORMSHIFTSZ-1:0]             Shifted        // is the sum zero
+);
+    assign Shifted = ShiftIn << ShiftAmt;
+
+endmodule