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`include "core/isa.sv"
`include "core/psr.sv"
`include "core/uarch.sv"
module core_decode_data
(
input word insn,
input psr_flags flags,
output alu_op op,
output reg_num rn,
rd,
output logic writeback,
update_flags,
restore_spsr,
zero_fst,
negate_fst,
negate_snd,
carry_in
);
assign rn = insn `FIELD_DATA_RN;
assign rd = insn `FIELD_DATA_RD;
always_comb begin
update_flags = insn `FIELD_DATA_S;
writeback = 1;
op = ALU_ADD;
zero_fst = 0;
negate_fst = 0;
negate_snd = 0;
carry_in = 0;
unique case(insn `FIELD_DATA_OPCODE)
`DATA_ADD: ;
`DATA_AND: op = ALU_AND;
`DATA_EOR: op = ALU_XOR;
`DATA_ORR: op = ALU_ORR;
`DATA_SUB: negate_snd = 1;
`DATA_RSB: negate_fst = 1;
`DATA_ADC: carry_in = flags.c;
`DATA_MOV: zero_fst = 1;
`DATA_CMN: writeback = 0;
`DATA_MVN: begin
zero_fst = 1;
negate_snd = 1;
end
`DATA_SBC: begin
negate_snd = 1;
carry_in = flags.c;
end
`DATA_RSC: begin
negate_fst = 1;
carry_in = flags.c;
end
`DATA_BIC: begin
op = ALU_AND;
negate_snd = 1;
carry_in = 1;
end
`DATA_TST: begin
op = ALU_AND;
writeback = 0;
end
`DATA_TEQ: begin
op = ALU_XOR;
writeback = 0;
end
`DATA_CMP: begin
writeback = 0;
negate_snd = 1;
end
endcase
restore_spsr = (rd == `R15) & update_flags;
if(restore_spsr)
update_flags = 0;
end
endmodule
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