| Line 222... |
Line 222... |
assign id_stall = ex_stall || raw_detected;
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assign id_stall = ex_stall || raw_detected;
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assign ex_stall = mem_stall || mul_busy || div_busy;
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assign ex_stall = mem_stall || mul_busy || div_busy;
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assign mem_stall = wb_stall || ( (dmem_read_o||dmem_write_o) && !dmem_done_i);
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assign mem_stall = wb_stall || ( (dmem_read_o||dmem_write_o) && !dmem_done_i);
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assign wb_stall = 0;
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assign wb_stall = 0;
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// Branch taken
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wire branch_taken;
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assign branch_taken = ( ex_mem_branch==1 && (ex_mem_aluout==32'h00000001) );
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// Name the System Configuration registers
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// Name the System Configuration registers
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wire[31:0] BadVAddr = SysCon[`SYSCON_BADVADDR];
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wire[31:0] BadVAddr = SysCon[`SYSCON_BADVADDR];
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wire[31:0] Status = SysCon[`SYSCON_STATUS];
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wire[31:0] Status = SysCon[`SYSCON_STATUS];
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wire[31:0] Cause = SysCon[`SYSCON_CAUSE];
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wire[31:0] Cause = SysCon[`SYSCON_CAUSE];
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wire[31:0] EPC = SysCon[`SYSCON_EPC];
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wire[31:0] EPC = SysCon[`SYSCON_EPC];
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| Line 330... |
Line 334... |
* - write the PC register
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* - write the PC register
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*
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*
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* DESCRIPTION:
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* DESCRIPTION:
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* This stage usually reads the next instruction from the PC address in memory and
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* This stage usually reads the next instruction from the PC address in memory and
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* then updates the PC value by incrementing it by 4.
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* then updates the PC value by incrementing it by 4.
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* When a hazard is detected this stage is idle.
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*/
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*/
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// A RAW hazard will stall the CPU
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// Handle hazards (if_stall = id_stall || !imem_done_i)
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if(if_stall) begin
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if(if_stall) begin
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// IF stall backward propagated from ID
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if(id_stall) begin
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if(id_stall) begin
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$display("INFO: CPU(%m)-IF: Fetching stalled and latch kept for following stalled pipeline stage");
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$display("INFO: CPU(%m)-IF: Fetching stalled like ID, latch keeps old value");
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// IMEM is not ready
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end else begin
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end else begin
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$display("INFO: CPU(%m)-IF: Fetching stalled and bubble inserted for following running pipeline stage");
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$display("INFO: CPU(%m)-IF: Fetching stalled due to IMEM, latch filled with bubble");
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if_id_opcode <= `BUBBLE;
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if_id_opcode <= `BUBBLE;
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end
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end
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end else begin
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end else begin
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// If branch taken update the Program Counter
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// If branch taken update the Program Counter (branch_taken = ex_mem_branch==1 && ex_mem_aluout==32'h00000001)
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if(ex_mem_branch==1 && ex_mem_aluout==32'h00000001) begin
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if(branch_taken) begin
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$display("INFO: CPU(%m)-IF: Bubble inserted due branch taken in EX/MEM instruction @ADDR=%X w/OPCODE=%X having ALUout=%X", ex_mem_addr, ex_mem_opcode, ex_mem_aluout);
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$display("INFO: CPU(%m)-IF: Bubble inserted due branch taken in EX/MEM instruction @ADDR=%X w/OPCODE=%X having ALUout=%X", ex_mem_addr, ex_mem_opcode, ex_mem_aluout);
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if_id_opcode <= `BUBBLE;
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if_id_opcode <= `BUBBLE;
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PC <= ex_mem_addrbranch;
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PC <= ex_mem_addrbranch;
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| Line 390... |
Line 395... |
*
|
*
|
* DESCRIPTION:
|
* DESCRIPTION:
|
* This stage decodes the instruction and puts the values for the ALU inputs
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* This stage decodes the instruction and puts the values for the ALU inputs
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*/
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*/
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|
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if(id_stall) begin
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if(branch_taken) begin
|
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$display("INFO: CPU(%m)-ID: Branch taken and bubble inserted");
|
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id_ex_opcode <=`BUBBLE;
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id_ex_alu_a <= 0;
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id_ex_alu_b <= 0;
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id_ex_alu_func <= `ALU_OP_ADD;
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id_ex_alu_signed <= 0;
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id_ex_addr <= if_id_addr;
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id_ex_addrnext <= 0;
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id_ex_addrjump <= 0;
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id_ex_addrbranch <= 0;
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id_ex_branch <= 0;
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id_ex_jump <= 0;
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id_ex_jr <= 0;
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id_ex_linked <= 0;
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id_ex_mult <= 0;
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id_ex_div <= 0;
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id_ex_load <= 0;
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id_ex_store <= 0;
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id_ex_destreg <= 0;
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id_ex_desthi <= 0;
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id_ex_destlo <= 0;
|
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end else if(id_stall) begin
|
|
|
if(ex_stall) begin
|
if(ex_stall) begin
|
$display("INFO: CPU(%m)-ID: Decoding stalled and latch kept for following stalled pipeline stage");
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$display("INFO: CPU(%m)-ID: Decoding stalled and latch kept");
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end else begin
|
end else begin
|
$display("INFO: CPU(%m)-ID: Decoding stalled and bubble inserted for following running pipeline stage");
|
$display("INFO: CPU(%m)-ID: Decoding stalled and bubble inserted");
|
id_ex_opcode <=`BUBBLE;
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id_ex_opcode <=`BUBBLE;
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id_ex_alu_a <= 0;
|
id_ex_alu_a <= 0;
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id_ex_alu_b <= 0;
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id_ex_alu_b <= 0;
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id_ex_alu_func <= `ALU_OP_ADD;
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id_ex_alu_func <= `ALU_OP_ADD;
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id_ex_alu_signed <= 0;
|
id_ex_alu_signed <= 0;
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| Line 1733... |
Line 1760... |
*/
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*/
|
|
|
if(ex_stall) begin
|
if(ex_stall) begin
|
|
|
if(mem_stall) begin
|
if(mem_stall) begin
|
$display("INFO: CPU(%m)-EX: Execution stalled and latch kept for following stalled pipeline stage");
|
$display("INFO: CPU(%m)-EX: Execution stalled and latch kept");
|
end else begin
|
end else begin
|
$display("INFO: CPU(%m)-EX: Execution stalled and bubble inserted for following running pipeline stage");
|
$display("INFO: CPU(%m)-EX: Execution stalled and bubble inserted");
|
ex_mem_opcode <= `BUBBLE;
|
ex_mem_opcode <= `BUBBLE;
|
ex_mem_addr <= id_ex_addr;
|
ex_mem_addr <= id_ex_addr;
|
ex_mem_addrnext <= 0;
|
ex_mem_addrnext <= 0;
|
ex_mem_destreg <= 0;
|
ex_mem_destreg <= 0;
|
ex_mem_desthi <= 0;
|
ex_mem_desthi <= 0;
|
