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Rename reg buffer signals

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Markus Wegmann 2017-01-08 11:57:45 +01:00
parent 099673de2b
commit 659e234be0
1 changed files with 22 additions and 22 deletions
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44
id_stage.sv
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@ -117,7 +117,7 @@ module riscv_id_stage
// CONFIG_REGION: MERGE_ID_EX // CONFIG_REGION: MERGE_ID_EX
`ifdef MERGE_ID_EX `ifdef MERGE_ID_EX
output logic id_wait_o, output logic id_wait_o, // We did not yet buffer the register ports
`endif `endif
// Pipeline ID/EX // Pipeline ID/EX
@ -531,8 +531,9 @@ module riscv_id_stage
// CONFIG_REGION: MERGE_ID_EX // CONFIG_REGION: MERGE_ID_EX
`ifdef MERGE_ID_EX `ifdef MERGE_ID_EX
logic [31:0] reg_buffer_s1_Q, reg_buffer_s2_Q; // As we have a latched register file, we need to buffer the register ports to prevent a time loop over the ALU
enum logic { WAIT_WRITE_BACK, COMPUTING } buffering_regs_Q, buffering_regs_n; logic [31:0] reg_buffer_a_Q, reg_buffer_b_Q;
enum logic { WAIT_WRITE_BACK, COMPUTING } buffer_fsm_Q, buffer_fsm_n;
`endif // MERGE_ID_EX `endif // MERGE_ID_EX
@ -722,8 +723,8 @@ module riscv_id_stage
// CONFIG_REGION: MERGE_ID_EX // CONFIG_REGION: MERGE_ID_EX
`ifdef MERGE_ID_EX `ifdef MERGE_ID_EX
// JALR: Cannot forward RS1, since the path is too long // JALR: Cannot forward RS1, since the path is too long
JT_JALR: jump_target = reg_buffer_s1_Q + imm_i_type; JT_JALR: jump_target = reg_buffer_a_Q + imm_i_type;
default: jump_target = reg_buffer_s1_Q + imm_i_type; default: jump_target = reg_buffer_a_Q + imm_i_type;
`else `else
// JALR: Cannot forward RS1, since the path is too long // JALR: Cannot forward RS1, since the path is too long
JT_JALR: jump_target = regfile_data_ra_id + imm_i_type; JT_JALR: jump_target = regfile_data_ra_id + imm_i_type;
@ -787,8 +788,8 @@ module riscv_id_stage
`endif `endif
// CONFIG_REGION: MERGE_ID_EX // CONFIG_REGION: MERGE_ID_EX
`ifdef MERGE_ID_EX `ifdef MERGE_ID_EX
SEL_REGFILE: operand_a_fw_id = reg_buffer_s1_Q; SEL_REGFILE: operand_a_fw_id = reg_buffer_a_Q;
default: operand_a_fw_id = reg_buffer_s1_Q; default: operand_a_fw_id = reg_buffer_a_Q;
`else `else
SEL_FW_WB: operand_a_fw_id = regfile_wdata_wb_i; SEL_FW_WB: operand_a_fw_id = regfile_wdata_wb_i;
SEL_REGFILE: operand_a_fw_id = regfile_data_ra_id; SEL_REGFILE: operand_a_fw_id = regfile_data_ra_id;
@ -907,8 +908,8 @@ module riscv_id_stage
`endif // MERGE_ID_EX `endif // MERGE_ID_EX
// CONFIG_REGION: MERGE_ID_EX // CONFIG_REGION: MERGE_ID_EX
`ifdef MERGE_ID_EX `ifdef MERGE_ID_EX
SEL_REGFILE: operand_b_fw_id = reg_buffer_s2_Q; SEL_REGFILE: operand_b_fw_id = reg_buffer_b_Q;
default: operand_b_fw_id = reg_buffer_s2_Q; default: operand_b_fw_id = reg_buffer_b_Q;
`else `else
SEL_FW_WB: operand_b_fw_id = regfile_wdata_wb_i; SEL_FW_WB: operand_b_fw_id = regfile_wdata_wb_i;
SEL_REGFILE: operand_b_fw_id = regfile_data_rb_id; SEL_REGFILE: operand_b_fw_id = regfile_data_rb_id;
@ -1778,41 +1779,40 @@ module riscv_id_stage
always_ff @(posedge clk or negedge rst_n) begin always_ff @(posedge clk or negedge rst_n) begin
if(~rst_n) begin if(~rst_n) begin
reg_buffer_s1_Q <= 32'b0; reg_buffer_a_Q <= 32'b0;
reg_buffer_s2_Q <= 32'b0; reg_buffer_b_Q <= 32'b0;
buffering_regs_Q <= WAIT_WRITE_BACK; buffer_fsm_Q <= WAIT_WRITE_BACK;
end else begin end else begin
if ((buffering_regs_Q == WAIT_WRITE_BACK && (buffering_regs_n == COMPUTING))) // TODO: Move to combinational process if ((buffer_fsm_Q == WAIT_WRITE_BACK && (buffer_fsm_n == COMPUTING))) // TODO: Move to combinational process
begin begin
reg_buffer_s1_Q <= regfile_data_ra_id; reg_buffer_a_Q <= regfile_data_ra_id;
reg_buffer_s2_Q <= regfile_data_rb_id; reg_buffer_b_Q <= regfile_data_rb_id;
end end
buffering_regs_Q <= buffering_regs_n; buffer_fsm_Q <= buffer_fsm_n;
end end
end end
always_comb always_comb
begin begin
buffering_regs_n = buffering_regs_Q; buffer_fsm_n = buffer_fsm_Q;
case (buffering_regs_Q) case (buffer_fsm_Q)
WAIT_WRITE_BACK: begin WAIT_WRITE_BACK: begin
if (~regfile_we_wb_i & instr_valid_i) if (~regfile_we_wb_i & instr_valid_i)
buffering_regs_n = COMPUTING; buffer_fsm_n = COMPUTING;
end end
COMPUTING: begin COMPUTING: begin
if (id_ready_o) if (id_ready_o)
buffering_regs_n = WAIT_WRITE_BACK; buffer_fsm_n = WAIT_WRITE_BACK;
// TODO: Introduce shortcut sinc we know that no write back is pending and that there won't be a next writeback
end end
default : /* default */; default : /* default */;
endcase endcase
end end
assign id_wait_o = (buffering_regs_Q == WAIT_WRITE_BACK); assign id_wait_o = (buffer_fsm_Q == WAIT_WRITE_BACK);
`endif // MERGE_ID_EX `endif // MERGE_ID_EX