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Fix timings for STA

master
Denis Tereshkin 4 weeks ago
parent
63d9b4cf2a
commit
e66e89bbd9
2 changed files with 234 additions and 115 deletions
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  1. 343
      src/cpu.verilog
  2. 6
      src/slon.sby

343
src/cpu.verilog
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@ -11,7 +11,6 @@ module cpu @@ -11,7 +11,6 @@ module cpu
`include "parameters.vh"
localparam STATE_START_1 = 4'hc;
localparam STATE_START_2 = 4'hd;
localparam STATE_START_3 = 4'he;
localparam STATE_START_4 = 4'hf;
@ -27,6 +26,7 @@ module cpu @@ -27,6 +26,7 @@ module cpu
localparam STATE_EXECUTE_IDX_2 = 9;
localparam STATE_EXECUTE_POST_IDX_1 = 10;
localparam STATE_EXECUTE_POST_IDX_2 = 11;
localparam STATE_DELAY = 12;
localparam
READ_SOURCE_NONE = 2'h0,
@ -87,6 +87,8 @@ localparam @@ -87,6 +87,8 @@ localparam
logic [1:0] pending_y_read;
logic pending_rel_branch;
wire is_arith;
logic [2:0] extra_timing;
reg [3:0] state_after_delay;
initial A = 0;
initial X = 0;
@ -102,12 +104,13 @@ initial pending_y_read = 0; @@ -102,12 +104,13 @@ initial pending_y_read = 0;
initial pending_rel_branch = 0;
initial mem_aux_addr = 0;
initial instr = 0;
initial extra_timing = 0;
assign o_state[3:0] = state;
assign o_state[31:24] = A;
assign o_state[23:16] = X;
assign is_arith = (decoded_instr == I_ADC);
assign is_arith = (decoded_instr == I_ADC || decoded_instr == I_SBC);
alu alui(
.A(alu_op_1),
@ -236,61 +239,77 @@ always_comb @@ -236,61 +239,77 @@ always_comb
alu_op_c = P[P_C];
alu_op_sel = OP_ADC;
end
else if (decoded_instr == I_SBC)
begin
alu_op_c = P[P_C];
alu_op_sel = OP_SUB;
end
end
end
always @(posedge clk)
if (state == STATE_FETCH)
if (extra_timing > 0)
begin
extra_timing <= extra_timing - 1'b1;
end
else if (state == STATE_FETCH)
begin
if (pending_a_read == READ_SOURCE_MEM)
if (extra_timing > 0)
begin
A <= mem_data;
P[P_Z] <= (mem_data == 0);
P[P_N] <= mem_data[7];
extra_timing <= extra_timing - 1'b1;
end
else if (pending_a_read == READ_SOURCE_ALU)
else
begin
A <= alu_op_result;
P[P_Z] <= alu_z;
P[P_N] <= alu_n;
if (is_arith)
if (pending_a_read == READ_SOURCE_MEM)
begin
P[P_C] <= alu_c;
P[P_V] <= alu_v;
A <= mem_data;
P[P_Z] <= (mem_data == 0);
P[P_N] <= mem_data[7];
end
end
pending_a_read <= READ_SOURCE_NONE;
else if (pending_a_read == READ_SOURCE_ALU)
begin
A <= alu_op_result;
P[P_Z] <= alu_z;
P[P_N] <= alu_n;
if (is_arith)
begin
P[P_C] <= alu_c;
P[P_V] <= alu_v;
end
end
pending_a_read <= READ_SOURCE_NONE;
if (pending_x_read == READ_SOURCE_MEM)
begin
X <= mem_data;
P[P_Z] <= (mem_data == 0);
P[P_N] <= mem_data[7];
end
else if (pending_x_read == READ_SOURCE_ALU)
begin
X <= alu_op_result;
P[P_Z] <= alu_z;
P[P_N] <= alu_n;
end
pending_x_read <= READ_SOURCE_NONE;
if (pending_x_read == READ_SOURCE_MEM)
begin
X <= mem_data;
P[P_Z] <= (mem_data == 0);
P[P_N] <= mem_data[7];
end
else if (pending_x_read == READ_SOURCE_ALU)
begin
X <= alu_op_result;
P[P_Z] <= alu_z;
P[P_N] <= alu_n;
end
pending_x_read <= READ_SOURCE_NONE;
if (pending_y_read == READ_SOURCE_MEM)
begin
Y <= mem_data;
P[P_Z] <= (mem_data == 0);
P[P_N] <= mem_data[7];
end
else if (pending_y_read == READ_SOURCE_ALU)
begin
Y <= alu_op_result;
P[P_Z] <= alu_z;
P[P_N] <= alu_n;
end
pending_y_read <= READ_SOURCE_NONE;
if (pending_y_read == READ_SOURCE_MEM)
begin
Y <= mem_data;
P[P_Z] <= (mem_data == 0);
P[P_N] <= mem_data[7];
end
else if (pending_y_read == READ_SOURCE_ALU)
begin
Y <= alu_op_result;
P[P_Z] <= alu_z;
P[P_N] <= alu_n;
end
pending_y_read <= READ_SOURCE_NONE;
PC <= PC + 1;
state <= STATE_EXECUTE;
PC <= PC + 1;
state <= STATE_EXECUTE;
end
end
else if (state == STATE_EXECUTE)
begin
@ -319,7 +338,8 @@ always @(posedge clk) @@ -319,7 +338,8 @@ always @(posedge clk)
else if (decoded_instr == I_EOR ||
decoded_instr == I_AND ||
decoded_instr == I_ORA ||
decoded_instr == I_ADC)
decoded_instr == I_ADC ||
decoded_instr == I_SBC)
begin
pending_a_read <= READ_SOURCE_ALU;
end
@ -347,6 +367,10 @@ always @(posedge clk) @@ -347,6 +367,10 @@ always @(posedge clk)
begin
mem_sel <= DMUX_AUX;
state <= STATE_EXECUTE_POST_IDX_1;
if (decoded_instr == I_STA)
begin
extra_timing <= 1;
end
end
else if (address_code == ADDR_MODE_IMPLIED)
begin
@ -377,7 +401,14 @@ always @(posedge clk) @@ -377,7 +401,14 @@ always @(posedge clk)
end
else if (state == STATE_EXECUTE_ZPX)
begin
mem_aux_addr <= mem_data + X;
if (decoded_instr != I_LDX)
begin
mem_aux_addr <= mem_data + X;
end
else
begin
mem_aux_addr <= mem_data + Y;
end
state <= STATE_EXECUTE_ZP;
end
else if (state == STATE_EXECUTE_ZP)
@ -399,7 +430,11 @@ always @(posedge clk) @@ -399,7 +430,11 @@ always @(posedge clk)
begin
pending_y_read <= READ_SOURCE_MEM;
end
else
else if (decoded_instr == I_ORA ||
decoded_instr == I_AND ||
decoded_instr == I_EOR ||
decoded_instr == I_ADC ||
decoded_instr == I_SBC)
begin
pending_a_read <= READ_SOURCE_ALU;
end
@ -446,6 +481,7 @@ always @(posedge clk) @@ -446,6 +481,7 @@ always @(posedge clk)
begin
mem_aux_addr <= mem_data;
state <= STATE_EXECUTE_DATA_2;
PC <= PC + 1'b1;
end
else if (state == STATE_FETCH_DATA_2)
begin
@ -455,35 +491,36 @@ always @(posedge clk) @@ -455,35 +491,36 @@ always @(posedge clk)
state <= STATE_EXECUTE_DATA_2;
PC <= PC + 1'b1;
end
else if (state == STATE_EXECUTE_DATA_2)
begin
mem_sel <= DMUX_PC;
state <= STATE_FETCH;
else if (state == STATE_EXECUTE_DATA_2)
begin
mem_sel <= DMUX_PC;
state <= STATE_FETCH;
if (decoded_instr == I_EOR ||
decoded_instr == I_AND ||
decoded_instr == I_ORA ||
decoded_instr == I_ADC)
begin
pending_a_read <= READ_SOURCE_ALU;
end
else if(decoded_instr == I_LDA)
begin
pending_a_read <= READ_SOURCE_MEM;
end
else if(decoded_instr == I_LDX)
begin
pending_x_read <= READ_SOURCE_MEM;
end
else if(decoded_instr == I_LDY)
begin
pending_y_read <= READ_SOURCE_MEM;
end
else if(decoded_instr == I_JMP)
begin
PC <= mem_addr;
end
end
if (decoded_instr == I_EOR ||
decoded_instr == I_AND ||
decoded_instr == I_ORA ||
decoded_instr == I_ADC ||
decoded_instr == I_SBC)
begin
pending_a_read <= READ_SOURCE_ALU;
end
else if(decoded_instr == I_LDA)
begin
pending_a_read <= READ_SOURCE_MEM;
end
else if(decoded_instr == I_LDX)
begin
pending_x_read <= READ_SOURCE_MEM;
end
else if(decoded_instr == I_LDY)
begin
pending_y_read <= READ_SOURCE_MEM;
end
else if(decoded_instr == I_JMP)
begin
PC <= mem_addr;
end
end
always_comb
begin
@ -491,13 +528,10 @@ always_comb @@ -491,13 +528,10 @@ always_comb
mem_wr = 0;
if (state == STATE_EXECUTE_DATA_2)
begin
if (address_code == ADDR_MODE_ABSOLUTE)
if(decoded_instr == I_STA)
begin
if(decoded_instr == I_STA)
begin
mem_data_wr = A;
mem_wr = 1'b1;
end
mem_data_wr = A;
mem_wr = 1'b1;
end
end
else if (state == STATE_EXECUTE_ZP)
@ -554,12 +588,13 @@ always @(posedge clk) @@ -554,12 +588,13 @@ always @(posedge clk)
f6_past_valid <= 1;
logic [7:0] f_instr_count;
initial f_instr_count = 0;
always @(posedge clk)
if (state == STATE_FETCH)
if (state == STATE_FETCH && $past(state) != STATE_FETCH)
f_instr_count <= f_instr_count + 1'b1;
always @(posedge clk)
if (f2_past_valid && state == STATE_FETCH)
if (f2_past_valid && state == STATE_FETCH && $past(state) != STATE_FETCH)
begin
f_prev_instruction <= $past(decoded_instr);
f_prev_addr_code <= $past(address_code);
@ -635,25 +670,29 @@ always_comb @@ -635,25 +670,29 @@ always_comb
end
always @(posedge clk)
if (f2_past_valid && state == STATE_EXECUTE_DATA_2)
if ($past(decoded_instr) == I_STA && $past(address_code) == ADDR_MODE_ABSOLUTE)
begin
assert(mem_wr == 1'b1);
assert(mem_data_wr == A);
assert(f_abs_address == mem_addr_eff);
if (f3_past_valid)
begin
assert(PC == $past(PC, 3) + 16'd3);
end
end
if (f_past_valid)
begin
assume(decoded_instr == I_LDA ||
decoded_instr == I_LDX ||
decoded_instr == I_LDY ||
decoded_instr == I_STA ||
decoded_instr == I_STX ||
decoded_instr == I_STY ||
decoded_instr == I_AND ||
decoded_instr == I_EOR ||
decoded_instr == I_ORA ||
decoded_instr == I_ADC ||
decoded_instr == I_SBC ||
decoded_instr == I_DEX ||
decoded_instr == I_DEY ||
decoded_instr == I_BNE ||
decoded_instr == I_JMP
);
assume(address_code != ADDR_MODE_INDIRECT);
end
always @(posedge clk)
if (f6_past_valid &&
state == STATE_EXECUTE &&
$past(state) == STATE_FETCH &&
($past(state, 2) == STATE_EXECUTE_DATA_2 ||
$past(state, 2) == STATE_EXECUTE_ZP ||
$past(state, 2) == STATE_EXECUTE))
if (f6_past_valid && state == STATE_EXECUTE && $past(state) == STATE_FETCH)
begin
if (f_prev_instruction == I_EOR)
assert(A == ($past(A) ^ $past(mem_data)));
@ -663,19 +702,23 @@ always @(posedge clk) @@ -663,19 +702,23 @@ always @(posedge clk)
assert(A == ($past(A) | $past(mem_data)));
else if (f_prev_instruction == I_ADC)
assert(A == ($past(A) + $past(mem_data) + $past(P[P_C])));
else if (f_prev_instruction == I_SBC)
assert(A == ($past(A) - $past(mem_data) - (1'b1 - $past(P[P_C]))));
else if (f_prev_instruction == I_LDA)
assert(A == $past(mem_data));
else if (f_prev_instruction == I_LDX)
assert(X == $past(mem_data));
else if (f_prev_instruction == I_LDY)
assert(Y == $past(mem_data));
else if (f_prev_instruction == I_STA)
assert(A == $past(A));
else
assume(0);
if (f_prev_instruction == I_STA)
begin
assert($past(mem_wr, 2) == 1'b1);
assert($past(mem_data_wr) == A);
assert($past(mem_data_wr, 2) == $past(A, 2));
end
else
begin
@ -687,7 +730,12 @@ always @(posedge clk) @@ -687,7 +730,12 @@ always @(posedge clk)
else if ($past(address_code, 2) == ADDR_MODE_ZP)
assert($past(mem_data, 2) == $past(mem_addr_eff, 2));
else if ($past(address_code, 2) == ADDR_MODE_INDEXED_ZP)
assert((($past(mem_data, 3) + $past(X, 3)) & 16'hff) == $past(mem_addr_eff, 2));
begin
if (f_prev_instruction != I_LDX)
assert((($past(mem_data, 3) + $past(X, 3)) & 16'hff) == $past(mem_addr_eff, 2));
else
assert((($past(mem_data, 3) + $past(Y, 3)) & 16'hff) == $past(mem_addr_eff, 2));
end
else if ($past(address_code, 2) == ADDR_MODE_INDEXED_ABSOLUTE_X)
assert((($past(f_abs_address, 2) + $past(X, 2)) & 16'hffff) == $past(mem_addr_eff, 2));
else if ($past(address_code, 2) == ADDR_MODE_INDEXED_ABSOLUTE_Y)
@ -702,21 +750,33 @@ always @(posedge clk) @@ -702,21 +750,33 @@ always @(posedge clk)
assert(($past(f_abs_address, 2) + $past(Y, 2)) == $past(mem_addr_eff, 2));
end
if (f_prev_instruction == I_LDX)
if (f_prev_instruction == I_LDX ||
f_prev_instruction == I_DEX)
begin
assert(P[P_Z] == (X == 0));
assert(P[P_N] == (X[7] == 1));
end
else if (f_prev_instruction == I_LDY)
else if (f_prev_instruction == I_LDY ||
f_prev_instruction == I_DEY)
begin
assert(P[P_Z] == (Y == 0));
assert(P[P_N] == (Y[7] == 1));
end
else
else if (f_prev_instruction == I_LDA ||
f_prev_instruction == I_ORA ||
f_prev_instruction == I_AND ||
f_prev_instruction == I_EOR ||
f_prev_instruction == I_ADC ||
f_prev_instruction == I_SBC)
begin
assert(P[P_Z] == (A == 0));
assert(P[P_N] == (A[7] == 1));
end
else
begin
assert(P[P_Z] == $past(P[P_Z], 2));
assert(P[P_N] == $past(P[P_N], 2));
end
if (f_prev_instruction == I_ADC)
begin
assert(P[P_C] == ({1'b0, $past(A)} +
@ -724,6 +784,13 @@ always @(posedge clk) @@ -724,6 +784,13 @@ always @(posedge clk)
{8'b0, $past(P[P_C])} >= 9'h100));
assert(P[P_V] == (($past(A[7]) ^ A[7]) & ($past(mem_data[7]) ^ A[7])));
end
else if (f_prev_instruction == I_SBC)
begin
assert(P[P_C] == ({1'b0, $past(A)} -
{1'b0, $past(mem_data)} -
{8'b0, ~$past(P[P_C])} >= 9'h100));
assert(P[P_V] == (($past(A[7]) ^ A[7]) & ($past(mem_data[7]) ^ A[7])));
end
else
begin
assert(P[P_C] == $past(P[P_C], 2));
@ -742,16 +809,37 @@ always @(posedge clk) @@ -742,16 +809,37 @@ always @(posedge clk)
assert(Y == $past(Y, 2));
end
if (f3_past_valid)
if (f6_past_valid)
begin
if ($past(address_code, 2) == ADDR_MODE_ABSOLUTE)
assert($past(PC, 2) == $past(PC, 5) + 16'd3);
assert($past(PC, 1) == $past(PC, 5) + 16'd3);
else if ($past(address_code, 2) == ADDR_MODE_ZP)
assert($past(PC, 2) == $past(PC, 4) + 16'd2);
assert($past(PC, 1) == $past(PC, 4) + 16'd2);
else if ($past(address_code, 2) == ADDR_MODE_INDEXED_ZP)
assert($past(PC, 2) == $past(PC, 5) + 16'd2);
assert($past(PC, 1) == $past(PC, 5) + 16'd2);
else if ($past(address_code, 2) == ADDR_MODE_IMMEDIATE)
assert($past(PC, 1) == $past(PC, 3) + 16'd2);
else if ($past(address_code, 2) == ADDR_MODE_PREINDEXED_INDIRECT)
assert($past(PC, 1) == $past(PC, 7) + 16'd2);
if (f_prev_instruction != I_STA)
begin
if ($past(address_code, 2) == ADDR_MODE_INDEXED_ABSOLUTE_X)
assert($past(PC, 1) == $past(PC, 5) + 16'd3);
else if ($past(address_code, 2) == ADDR_MODE_INDEXED_ABSOLUTE_Y)
assert($past(PC, 1) == $past(PC, 5) + 16'd3);
else if ($past(address_code, 2) == ADDR_MODE_POSTINDEXED_INDIRECT)
assert($past(PC, 1) == $past(PC, 6) + 16'd2);
end
else
begin
if ($past(address_code, 2) == ADDR_MODE_INDEXED_ABSOLUTE_X)
assert($past(PC, 1) == $past(PC, 5) + 16'd3);
else if ($past(address_code, 2) == ADDR_MODE_INDEXED_ABSOLUTE_Y)
assert($past(PC, 1) == $past(PC, 5) + 16'd3);
else if ($past(address_code, 2) == ADDR_MODE_POSTINDEXED_INDIRECT)
assert($past(PC, 1) == $past(PC, 7) + 16'd2);
end
end
end
@ -784,11 +872,10 @@ always @(posedge clk) @@ -784,11 +872,10 @@ always @(posedge clk)
end
always @(posedge clk)
if (f_past_valid)
assume(state != $past(state));
cover(state == STATE_EXECUTE);
always @(posedge clk)
cover(state == STATE_EXECUTE);
cover(f6_past_valid);
always @(posedge clk)
cover(f_instr_count > 16);
@ -804,6 +891,22 @@ always @(posedge clk) @@ -804,6 +891,22 @@ always @(posedge clk)
cover(address_code == ADDR_MODE_INDEXED_ABSOLUTE_Y);
cover(address_code == ADDR_MODE_INDEXED_ZP);
cover(address_code == ADDR_MODE_PREINDEXED_INDIRECT);
cover(address_code == ADDR_MODE_POSTINDEXED_INDIRECT);
end
end
always @(posedge clk)
begin
if (decoded_instr == I_SBC)
begin
cover(address_code == ADDR_MODE_IMMEDIATE);
cover(address_code == ADDR_MODE_ABSOLUTE);
cover(address_code == ADDR_MODE_ZP);
cover(address_code == ADDR_MODE_INDEXED_ABSOLUTE_X);
cover(address_code == ADDR_MODE_INDEXED_ABSOLUTE_Y);
cover(address_code == ADDR_MODE_INDEXED_ZP);
cover(address_code == ADDR_MODE_PREINDEXED_INDIRECT);
cover(address_code == ADDR_MODE_POSTINDEXED_INDIRECT);
end
end
@ -818,6 +921,21 @@ always @(posedge clk) @@ -818,6 +921,21 @@ always @(posedge clk)
cover(address_code == ADDR_MODE_INDEXED_ABSOLUTE_Y);
cover(address_code == ADDR_MODE_INDEXED_ZP);
cover(address_code == ADDR_MODE_PREINDEXED_INDIRECT);
cover(address_code == ADDR_MODE_POSTINDEXED_INDIRECT);
end
end
always @(posedge clk)
begin
if (decoded_instr == I_STA)
begin
cover(address_code == ADDR_MODE_ZP);
cover(address_code == ADDR_MODE_INDEXED_ZP);
cover(address_code == ADDR_MODE_ABSOLUTE);
cover(address_code == ADDR_MODE_INDEXED_ABSOLUTE_X);
cover(address_code == ADDR_MODE_INDEXED_ABSOLUTE_Y);
cover(address_code == ADDR_MODE_PREINDEXED_INDIRECT);
cover(address_code == ADDR_MODE_POSTINDEXED_INDIRECT);
end
end
@ -844,6 +962,7 @@ always @(posedge clk) @@ -844,6 +962,7 @@ always @(posedge clk)
cover(address_code == ADDR_MODE_INDEXED_ABSOLUTE_Y);
cover(address_code == ADDR_MODE_INDEXED_ZP);
cover(address_code == ADDR_MODE_PREINDEXED_INDIRECT);
cover(address_code == ADDR_MODE_POSTINDEXED_INDIRECT);
end
end

6
src/slon.sby
Unescape View File

@ -4,12 +4,12 @@ cvr @@ -4,12 +4,12 @@ cvr
[options]
prf: mode prove
prf: depth 30
prf: depth 20
cvr: mode cover
cvr: depth 60
cvr: depth 100
[engines]
smtbmc yices
smtbmc --unroll yices
[script]
read -formal decoder.verilog

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