From e97d445908f39a3a1a215a824f52b283147e6195 Mon Sep 17 00:00:00 2001
From: Alejandro Soto <alejandro@34project.org>
Date: Sun, 2 Oct 2022 09:49:48 -0600
Subject: Major shifter-ALU redesign

The shifter unit now works in parallel with the ALU and is no longer
part of it. Instructions that use the shifter as input to the ALU will
now take an additional cycle, unless the control unit can detect a
"trivial shift" situation where the shifter's output will be the same as
its input. This change improves Fmax substantially.
---
 rtl/core/decode/data.sv   | 12 ++++++------
 rtl/core/decode/decode.sv | 24 ++++++++++++------------
 2 files changed, 18 insertions(+), 18 deletions(-)

(limited to 'rtl/core/decode')

diff --git a/rtl/core/decode/data.sv b/rtl/core/decode/data.sv
index 4dc51a4..a649440 100644
--- a/rtl/core/decode/data.sv
+++ b/rtl/core/decode/data.sv
@@ -3,13 +3,13 @@
 
 module core_decode_data
 (
-	input  word       insn,
+	input  word        insn,
 
-	output alu_decode decode,
-	output logic      writeback,
-	                  update_flags,
-	                  restore_spsr,
-	                  undefined
+	output data_decode decode,
+	output logic       writeback,
+	                   update_flags,
+	                   restore_spsr,
+	                   undefined
 );
 
 	alu_op op;
diff --git a/rtl/core/decode/decode.sv b/rtl/core/decode/decode.sv
index af80135..f7d7be8 100644
--- a/rtl/core/decode/decode.sv
+++ b/rtl/core/decode/decode.sv
@@ -6,13 +6,13 @@ module core_decode
 	input  word       insn,
 	input  psr_flags  flags,
 
-	output logic      execute,
-	                  undefined,
-	                  writeback,
-	                  update_flags,
-	                  branch,
-	output ptr        branch_offset,
-	output alu_decode alu
+	output logic       execute,
+	                   undefined,
+	                   writeback,
+	                   update_flags,
+	                   branch,
+	output ptr         branch_offset,
+	output data_decode data_ctrl
 );
 
 	logic cond_undefined;
@@ -38,11 +38,11 @@ module core_decode
 	logic restore_spsr;
 
 	logic data_writeback, data_update_flags, data_undefined;
-	alu_decode data_alu;
+	data_decode data;
 
 	core_decode_data group_data
 	(
-		.decode(data_alu),
+		.decode(data),
 		.writeback(data_writeback),
 		.update_flags(data_update_flags),
 		.undefined(data_undefined),
@@ -55,20 +55,20 @@ module core_decode
 		branch = 0;
 		writeback = 0;
 		update_flags = 0;
-		alu = {($bits(alu)){1'bx}};
+		data_ctrl = {($bits(data_ctrl)){1'bx}};
 
 		priority casez(insn `FIELD_OP)
 			`GROUP_B: begin
 				branch = 1;
 				if(branch_link) begin
-					alu.rd = `R14;
+					data_ctrl.rd = `R14;
 					writeback = 1;
 					//TODO: Valor de LR
 				end
 			end
 
 			`GROUP_ALU: begin
-				alu = data_alu;
+				data_ctrl = data;
 				writeback = data_writeback;
 				update_flags = data_update_flags;
 				undefined = undefined | data_undefined;
-- 
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