Split decoding of flexible second operand out of data instructions

1 files changed, 7 insertions, 62 deletions

diff --git a/rtl/core/decode/data.sv b/rtl/core/decode/data.sv
index a649440..e2a44df 100644
--- a/rtl/core/decode/data.sv
+++ b/rtl/core/decode/data.sv
@@ -6,45 +6,25 @@ module core_decode_data
 	input  word        insn,
 
 	output data_decode decode,
-	output logic       writeback,
+	output logic       snd_is_imm,
+	                   snd_shift_by_reg_if_reg,
+	                   writeback,
 	                   update_flags,
-	                   restore_spsr,
-	                   undefined
+	                   restore_spsr
 );
 
 	alu_op op;
-	reg_num rn, rd, r_snd, r_shift;
-	logic snd_shift_by_reg, snd_is_imm, shl, shr, ror, put_carry, sign_extend;
-	logic[7:0] imm;
-	logic[5:0] shift_imm;
+	reg_num rn, rd;
 
 	assign decode.op = op;
 	assign decode.rn = rn;
 	assign decode.rd = rd;
-	assign decode.r_snd = r_snd;
-	assign decode.r_shift = r_shift;
-	assign decode.snd_shift_by_reg = snd_shift_by_reg;
-	assign decode.snd_is_imm = snd_is_imm;
-	assign decode.shl = shl;
-	assign decode.shr = shr;
-	assign decode.ror = ror;
-	assign decode.put_carry = put_carry;
-	assign decode.sign_extend = sign_extend;
-	assign decode.imm = imm;
-	assign decode.shift_imm = shift_imm;
-
 	assign rn = insn `FIELD_DATA_RN;
 	assign rd = insn `FIELD_DATA_RD;
 	assign op = insn `FIELD_DATA_OPCODE;
-	assign r_snd = insn `FIELD_DATA_RM;
-	assign r_shift = insn `FIELD_DATA_RS;
-	assign imm = insn `FIELD_DATA_IMM8;
-	assign snd_is_imm = insn `FIELD_DATA_IMM;
-	assign snd_shift_by_reg = ~snd_is_imm & insn `FIELD_DATA_REGSHIFT;
-	assign undefined = snd_shift_by_reg & insn `FIELD_DATA_ZEROIFREG;
 
-	logic[1:0] shift_op;
-	assign shift_op = insn `FIELD_DATA_SHIFT;
+	assign snd_is_imm = insn `FIELD_DATA_IMM;
+	assign snd_shift_by_reg_if_reg = insn `FIELD_DATA_REGSHIFT;
 
 	always_comb begin
 		unique case(op)
@@ -60,41 +40,6 @@ module core_decode_data
 
 		if(restore_spsr)
 			update_flags = 0;
-
-		ror = snd_is_imm;
-		shr = ~snd_is_imm;
-		put_carry = 0;
-		sign_extend = 1'bx;
-
-		if(snd_is_imm)
-			shift_imm = {1'b0, insn `FIELD_DATA_ROR8, 1'b0};
-		else begin
-			shift_imm = {1'b0, insn `FIELD_DATA_SHIFTIMM};
-
-			case(shift_op)
-				`SHIFT_LSL: shr = 0;
-				`SHIFT_LSR: sign_extend = 0;
-				`SHIFT_ASR: sign_extend = 1;
-				`SHIFT_ROR: ;
-			endcase
-
-			if(~snd_shift_by_reg & (shift_imm == 0))
-				case(shift_op)
-					`SHIFT_LSL: ;
-
-					`SHIFT_LSR, `SHIFT_ASR:
-						shift_imm = 6'd32;
-
-					`SHIFT_ROR: begin
-						// RRX
-						shift_imm = 6'd1;
-						put_carry = 1;
-						sign_extend = 0;
-					end
-				endcase
-			else if(shift_op == `SHIFT_ROR)
-				ror = 1;
-		end
 	end
 
 endmodule