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Removed duplicate code and improved microcode entry

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This commit is contained in:
(Tim) Efthimis Kritikos 2023-05-27 17:59:52 +01:00
parent 79d598fc64
commit d2a98c02ff
1 changed files with 40 additions and 46 deletions
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86
system/processor.v
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@ -198,7 +198,10 @@ always @(negedge reset) begin
end end
always @(posedge reset) begin always @(posedge reset) begin
proc_state <= `PROC_RESET; proc_state <= `PROC_RESET;
valid_instruction_ack <= 0; // needs early init /* need early init */
valid_instruction_ack <= 0;
instant_response <= 0;
stalled_response <= 0;
end end
/*** Processor stages ***/ /*** Processor stages ***/
@ -216,29 +219,55 @@ reg owe_set_init;
reg VALID_INSTRUCTION_lc; reg VALID_INSTRUCTION_lc;
always @(VALID_INSTRUCTION)begin VALID_INSTRUCTION_lc<=VALID_INSTRUCTION; end always @(VALID_INSTRUCTION)begin VALID_INSTRUCTION_lc<=VALID_INSTRUCTION; end
reg instant_response, stalled_response;
reg wait_exec;
always @(next_exec) begin always @(next_exec) begin
proc_state<=`PROC_DE_STATE_ENTRY; proc_state<=`PROC_DE_STATE_ENTRY;
if ( VALID_INSTRUCTION_lc == 1 && SIMPLE_MICRO == 0 && DE_DEPENDS_ON_PREVIOUS == 0 && ucode_seq_addr_entry==`UCODE_NO_INSTRUCTION) begin if ( VALID_INSTRUCTION_lc == 1 && DE_DEPENDS_ON_PREVIOUS == 0 && ucode_seq_addr_entry==`UCODE_NO_INSTRUCTION) begin
instant_response <= !instant_response;
end else begin
wait_exec<=0;
end
end
always @(instant_response or stalled_response) begin
DE_OUTPUT_sampled <= DE_OUTPUT;
if(SIMPLE_MICRO==0||owe_set_init==1)begin
/* This runs at the start of the execution of an 8086 instruction */
`ifdef DEBUG_PC_ADDRESS `ifdef DEBUG_PC_ADDRESS
$display("Running command at %04x (%08x)",INSTRUCTION_LOCATION,INSTRUCTION); $display("Running command at %04x (%08x)",INSTRUCTION_LOCATION,INSTRUCTION);
`endif `endif
`ifdef CALCULATE_IPC `ifdef CALCULATE_IPC
new_instruction <= !new_instruction; new_instruction <= !new_instruction;
`endif `endif
DE_OUTPUT_sampled <= DE_OUTPUT;
set_initial_values<= !set_initial_values;
valid_instruction_ack <= !valid_instruction_ack; valid_instruction_ack <= !valid_instruction_ack;
owe_set_init<=0;
set_initial_values<= !set_initial_values;
ProgCount <= INSTRUCTION_LOCATION+{12'b0,instr_end}; ProgCount <= INSTRUCTION_LOCATION+{12'b0,instr_end};
INSTRUCTION_BUFFER<=INSTRUCTION[23:0]; INSTRUCTION_BUFFER<=INSTRUCTION[23:0];
wait_exec<=1; end
valid_exec_data<=!valid_exec_data;
if ( (ucode_seq_addr==`UCODE_NO_INSTRUCTION) && (ucode_seq_addr_entry!=`UCODE_NO_INSTRUCTION) )begin
/* switch to microcode decoding */
ucode_seq_addr <= ucode_seq_addr_entry;
SIMPLE_MICRO <= 1;
/*keep proc_state the same and rerun decode this time with all the data from the microcode rom*/
end else begin end else begin
wait_exec<=0; /* This runs at the start of each execution cycle, with microcode this is more than once per 8086 instruction */
valid_exec_data<=!valid_exec_data;
if( SIMPLE_MICRO == 1 ) begin
ucode_seq_addr <= ucode_seq_addr_entry; /*Reused for next address*/
if( ucode_seq_addr_entry == `UCODE_NO_INSTRUCTION )begin
/*Finished microcode*/
SIMPLE_MICRO <= 0;
end
end
wait_exec<=1;
end end
end end
reg wait_exec;
always @(posedge clock) begin always @(posedge clock) begin
case(proc_state) case(proc_state)
`PROC_RESET:begin `PROC_RESET:begin
@ -252,43 +281,8 @@ always @(posedge clock) begin
valid_exec_data<=0; valid_exec_data<=0;
end end
`PROC_DE_STATE_ENTRY:begin `PROC_DE_STATE_ENTRY:begin
if( VALID_INSTRUCTION==1 || SIMPLE_MICRO == 1 ) begin if ( ( VALID_INSTRUCTION==1 || SIMPLE_MICRO == 1 ) && wait_exec==0) begin
if(wait_exec==0) begin stalled_response <= !stalled_response;
DE_OUTPUT_sampled <= DE_OUTPUT;
if(SIMPLE_MICRO==0||owe_set_init==1)begin
/* This runs at the start of the execution of an 8086 instruction */
`ifdef DEBUG_PC_ADDRESS
$display("Running command at %04x (%08x)",INSTRUCTION_LOCATION,INSTRUCTION);
`endif
`ifdef CALCULATE_IPC
new_instruction <= !new_instruction;
`endif
valid_instruction_ack <= !valid_instruction_ack;
owe_set_init<=0;
set_initial_values<= !set_initial_values;
ProgCount <= INSTRUCTION_LOCATION+{12'b0,instr_end};
INSTRUCTION_BUFFER<=INSTRUCTION[23:0];
end
if ( (ucode_seq_addr==`UCODE_NO_INSTRUCTION) && (ucode_seq_addr_entry!=`UCODE_NO_INSTRUCTION) )begin
/* switch to microcode decoding */
ucode_seq_addr <= ucode_seq_addr_entry;
SIMPLE_MICRO <= 1;
/*keep proc_state the same and rerun decode this time with all the data from the microcode rom*/
end else begin
/* This runs at the start of each execution cycle, with microcode this is more than once per 8086 instruction */
valid_exec_data<=!valid_exec_data;
if( SIMPLE_MICRO == 1 ) begin
ucode_seq_addr <= ucode_seq_addr_entry; /*Reused for next address*/
if( ucode_seq_addr_entry == `UCODE_NO_INSTRUCTION )begin
/*Finished microcode*/
SIMPLE_MICRO <= 0;
end
end
wait_exec<=1;
end
end
end end
end end
`PROC_HALT:begin `PROC_HALT:begin