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`include "core/decode/isa.sv"
`include "core/uarch.sv"
module core_decode_data
(
input word insn,
output data_decode decode,
output logic snd_is_imm,
snd_shift_by_reg_if_reg,
writeback,
update_flags,
restore_spsr,
uses_rn
);
alu_op op;
reg_num rn, rd;
assign decode.op = op;
assign decode.rn = rn;
assign decode.rd = rd;
assign rn = insn `FIELD_DATA_RN;
assign rd = insn `FIELD_DATA_RD;
assign op = insn `FIELD_DATA_OPCODE;
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)
`ALU_CMP, `ALU_CMN, `ALU_TST, `ALU_TEQ:
writeback = 0;
default:
writeback = 1;
endcase
unique case(op)
`ALU_MOV, `ALU_MVN:
uses_rn = 0;
default:
uses_rn = 1;
endcase
update_flags = insn `FIELD_DATA_S;
restore_spsr = (rd == `R15) & update_flags;
if(restore_spsr)
update_flags = 0;
end
endmodule
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