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`include "core/uarch.sv"
module core_control_writeback
(
input logic clk,
rst_n,
input insn_decode dec,
input psr_flags alu_flags,
input word q_alu,
mem_data_rd,
input logic mem_ready,
mem_write,
input word mul_q_hi,
mul_q_lo,
input ctrl_cycle cycle,
next_cycle,
input word saved_base,
vector,
input reg_num ra,
popped,
mul_r_add_hi,
input logic issue,
pop_valid,
output reg_num rd,
final_rd,
output logic writeback,
final_writeback,
update_flags,
final_update_flags,
output word wr_value,
output psr_flags wb_alu_flags
);
reg_num last_rd;
always_comb begin
rd = last_rd;
unique case(next_cycle)
TRANSFER:
if(mem_ready)
rd = final_rd;
ISSUE, BASE_WRITEBACK:
rd = final_rd;
EXCEPTION:
rd = `R15;
MUL_HI_WB:
rd = mul_r_add_hi;
endcase
unique case(next_cycle)
ISSUE:
writeback = final_writeback;
TRANSFER:
writeback = mem_ready && !mem_write;
BASE_WRITEBACK:
writeback = !mem_write;
EXCEPTION, MUL_HI_WB:
writeback = 1;
default:
writeback = 0;
endcase
unique case(cycle)
TRANSFER:
wr_value = mem_data_rd;
BASE_WRITEBACK:
wr_value = saved_base;
MUL, MUL_HI_WB:
wr_value = mul_q_lo;
default:
// Ruta combinacional larga
wr_value = q_alu;
endcase
unique case(next_cycle)
TRANSFER:
if(mem_ready)
wr_value = mem_data_rd;
BASE_WRITEBACK:
wr_value = mem_data_rd;
EXCEPTION:
wr_value = vector;
MUL_HI_WB:
wr_value = mul_q_hi;
endcase
end
always_ff @(posedge clk or negedge rst_n)
if(!rst_n) begin
last_rd <= 0;
final_rd <= 0;
final_writeback <= 0;
update_flags <= 0;
final_update_flags <= 0;
wb_alu_flags <= {$bits(wb_alu_flags){1'b0}};
end else begin
last_rd <= rd;
wb_alu_flags <= alu_flags;
unique case(next_cycle)
ISSUE:
final_rd <= dec.data.rd;
TRANSFER:
if((cycle != TRANSFER || mem_ready) && pop_valid)
final_rd <= popped;
BASE_WRITEBACK:
final_rd <= ra;
EXCEPTION:
final_rd <= `R14;
endcase
unique case(next_cycle)
ISSUE:
final_writeback <= issue && dec.ctrl.writeback;
EXCEPTION:
final_writeback <= 1;
endcase
update_flags <= 0;
unique case(next_cycle)
ISSUE:
update_flags <= final_update_flags;
EXCEPTION:
final_update_flags <= 0;
endcase
unique case(next_cycle)
ISSUE:
final_update_flags <= issue && dec.psr.update_flags;
EXCEPTION:
final_update_flags <= 0;
endcase
end
endmodule
|
