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Fix instruction corruption issue in IF

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Sven Stucki 2015-08-18 17:49:37 +02:00
parent 0042daa8c9
commit 0da283fb58
1 changed files with 14 additions and 17 deletions
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31
if_stage.sv
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@ -191,7 +191,7 @@ module if_stage
end
end
assign current_pc_if_o = pc_if_offset ? {last_fetch_addr[31:2], 2'b10} : fetch_addr;
assign current_pc_if_o = last_fetch_addr + (pc_if_offset? 32'd2 : 32'd0);
always_comb
@ -299,18 +299,16 @@ module if_stage
fetch_fsm_ns = WAIT_REQ;
end else begin
// set PC
// next_pc already contains correct jump target, but need to
// handle special cases with compressed instructions here
sample_addr = 1'b1;
fetch_addr_n = {jump_target_i[31:2], 2'b0};
if (jump_target_i[1:0] == 2'b0) begin
// regular fetch
pc_if_offset_n = 1'b0;
fetch_fsm_ns = WAIT_ACK;
end else begin
// unaligned access
pc_if_offset_n = 1'b1;
fetch_fsm_ns = FETCH;
end
fetch_fsm_ns = FETCH;
// TODO: Already send request here?
end
end
@ -321,6 +319,7 @@ module if_stage
req_int = 1'b1;
if (ack_int) begin
req_int = 1'b0;
fetch_fsm_ns = WAIT_REQ;
end
end
@ -329,9 +328,7 @@ module if_stage
begin
sample_addr = 1'b0;
if (ack_int) begin
//sample_addr = 1'b1;
ack_o = 1'b1;
bypass_data_reg = 1'b0; // TODO: Use different signal for IF PC calculation
fetch_fsm_ns = WAIT_REQ;
end
end
@ -374,15 +371,15 @@ module if_stage
endcase
// jump handling
if (jump_in_ex_i == `BRANCH_JAL || jump_in_ex_i == `BRANCH_JALR) begin
next_pc = jump_target_i;
end else if (jump_in_ex_i == `BRANCH_COND) begin
// branch handling
if (branch_decision_i == 1'b1)
next_pc = jump_target_i;
else
next_pc = current_pc_if_o;
end
//if (jump_in_ex_i == `BRANCH_JAL || jump_in_ex_i == `BRANCH_JALR) begin
// next_pc = jump_target_i;
//end else if (jump_in_ex_i == `BRANCH_COND) begin
// // branch handling
// if (branch_decision_i == 1'b1)
// next_pc = jump_target_i;
// else
// next_pc = current_pc_if_o;
//end
if (pc_mux_boot_i)
next_pc = {boot_addr_i[31:5], `EXC_OFF_RST};
@ -455,7 +452,7 @@ module if_stage
begin : ENABLED_PIPE
instr_rdata_id_o <= instr_rdata_int;
if (pc_if_offset)
current_pc_id_o <= last_fetch_addr + (bypass_data_reg? 32'd2 : -2); // TODO: Cleanup
current_pc_id_o <= last_fetch_addr + ((fetch_fsm_cs != FETCH_NEXT)? 32'd2 : -2); // TODO: Cleanup
else
current_pc_id_o <= last_fetch_addr;
end