bslathi19/verilog6502
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This commit is contained in:
Byron Lathi
2026-05-04 23:00:32 -07:00
parent 79ce91669b
commit 3c8df89769
2 changed files with 128 additions and 15 deletions
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83
sim/verilog6502_32bit_test.py
View File

@@ -646,6 +646,89 @@ async def test_irq(dut):
assert int(dut.RDY_O.value) == 0
@cocotb.test
async def test_bra_always(dut):
cocotb.start_soon(Clock(dut.clk, CLK_PERIOD, unit="ns").start())
cocotb.start_soon(handle_memory(dut))
write_dword(0xfffffff4, 0xfffffd)
# L1: bra L1 0x80 0x03
# nop
# nop
# L2: bra L2
write_bytes(0xfffffd, [0x80, 0x3, 0x00, 0x00, 0x00, 0x80, 0xfe])
dut.RDY.value = Immediate(1)
dut.reset.value = Immediate(1)
for _ in range(10):
await RisingEdge(dut.clk)
dut.reset.value = 0
count = 0
async def count_address():
nonlocal count
while True:
await RisingEdge(dut.clk)
if int(dut.AB.value) == 0x01000004:
count+=1
cocotb.start_soon(count_address())
await Timer(1, "us")
assert count > 0
@cocotb.test
async def test_bra_never(dut):
cocotb.start_soon(Clock(dut.clk, CLK_PERIOD, unit="ns").start())
cocotb.start_soon(handle_memory(dut))
write_dword(0xfffffff4, 0xfffffd)
# lda #$00
# bne <anywhere>
# wai
write_bytes(0xfffffd, [0xa9, 0x00, 0xd0, 0x7f, 0xd0, 0x80, 0xd0, 0xfe, 0xcb])
dut.RDY.value = Immediate(1)
dut.reset.value = Immediate(1)
for _ in range(10):
await RisingEdge(dut.clk)
dut.reset.value = 0
expected_cpu_outputs = [
None, # ignore reset sequence
None,
None,
None,
None,
None,
None,
None,
None,
(0x00fffffd, False, None),
(0x00fffffe, False, None),
(0x00ffffff, False, None),
(0x01000000, False, None),
(0x01000001, False, None),
(0x01000002, False, None),
(0x01000003, False, None),
(0x01000004, False, None),
(0x01000005, False, None),
(0x01000006, False, None),
(0x01000006, False, None),
(0x01000006, False, None),
]
await check_instruction_sequence(dut, expected_cpu_outputs)
@cocotb.test
async def test_adc(dut):
cocotb.start_soon(Clock(dut.clk, CLK_PERIOD, unit="ns").start())

60
src/cpu_65c02.v
View File

@@ -72,6 +72,7 @@ reg [31:0] ABR; // Address Bus Register
wire [7:0] ADD; // Adder Hold Register (registered in ALU)
reg [7:0] alu_sr_0; // ALU output shift register 0
reg [7:0] alu_sr_1; // ALU output shift register 1
reg [7:0] alu_sr_2; // ALU output shift register 2
reg [7:0] DIHOLD; // Hold for Data In
reg DIHOLD_valid; //
@@ -294,7 +295,10 @@ parameter
RTS3 = 7'd76,
RTS4 = 7'd77,
RTI4 = 7'd78,
RTI5 = 7'd79;
RTI5 = 7'd79,
BRA3 = 7'd80,
BRA4 = 7'd81,
BRA5 = 7'd82;
`ifdef SIM
@@ -371,6 +375,9 @@ always @*
BRA0: statename = "BRA0";
BRA1: statename = "BRA1";
BRA2: statename = "BRA2";
BRA3: statename = "BRA3";
BRA4: statename = "BRA4";
BRA5: statename = "BRA5";
JMP0: statename = "JMP0";
JMP1: statename = "JMP1";
JMP2: statename = "JMP2";
@@ -415,11 +422,12 @@ always @*
RTS5: PC_temp = { DIMUX, ADD, alu_sr_0, alu_sr_1} + 2;
BRA1: PC_temp = { ABR[15:8], ADD };
BRA1: PC_temp = AB;
BRA2: PC_temp = AB;
BRA3: PC_temp = AB;
BRA4: PC_temp = AB;
JMPIX4,
BRA2: PC_temp = { ADD, PC[7:0] }; // TODO
BRK4: PC_temp = res ? 32'hFFFFFFF4 :
NMI_edge ? 32'hFFFFFFF8 : 32'hFFFFFFFC;
@@ -452,7 +460,11 @@ always @*
ABSX2,
FETCH,
BRA0,
BRA1,
BRA2,
BRA3,
BRA4,
BRA5,
BRK5,
JMPI0,
JMPI1,
@@ -502,11 +514,13 @@ always @*
RTI6,
ABS3: AB = { DIMUX, ADD, alu_sr_0, alu_sr_1};
BRA2,
JMPIX4,
ABSX4: AB = { ADD, ABR[23:0] }; // TODO
BRA1: AB = { ABR[15:8], ADD }; // TODO
BRA1: AB = { ABR[31:8], ADD };
BRA2: AB = { ABR[31:16], ADD, alu_sr_0 };
BRA3: AB = { ABR[31:24], ADD, alu_sr_0, alu_sr_1 };
BRA4: AB = { ADD, alu_sr_0, alu_sr_1, alu_sr_2 };
JSR0,
PUSH1,
@@ -782,6 +796,7 @@ always @(posedge clk) begin
alu_sr_0 <= DIMUX;
end
alu_sr_1 <= alu_sr_0;
alu_sr_2 <= alu_sr_1;
end
end
@@ -812,7 +827,10 @@ always @*
case( state )
READ: alu_op = op;
BRA1: alu_op = backwards ? OP_SUB : OP_ADD;
BRA1,
BRA2,
BRA3,
BRA4: alu_op = OP_ADD;
FETCH,
REG : alu_op = op;
@@ -849,7 +867,7 @@ always @*
*/
always @(posedge clk)
if( RDY )
if( RDY && state == BRA0)
backwards <= DIMUX[7];
/*
@@ -893,7 +911,10 @@ always @*
BRA0,
READ: AI = DIMUX;
BRA1: AI = ABR[15:8]; // don't use PCH in case we're TODO
BRA1,
BRA2,
BRA3,
BRA4: AI = backwards ? 8'hff : 0;
FETCH: AI = load_only ? 8'b0 : regfile;
@@ -910,7 +931,6 @@ always @*
always @*
case( state )
BRA1,
RTS1,
RTS2,
RTS3,
@@ -937,7 +957,10 @@ always @*
READ: BI = txb_ins ? (trb_ins ? ~regfile : regfile) : 8'h00;
BRA0: BI = PC[7:0]; // TODO
BRA0: BI = ABR[7:0];
BRA1: BI = ABR[15:8];
BRA2: BI = ABR[23:16];
BRA3: BI = ABR[31:24];
DECODE,
ABS3: BI = 8'hxx;
@@ -953,6 +976,8 @@ always @*
case( state )
INDY2,
BRA1,
BRA2,
BRA3,
JMPIX1,
ABSX1,
ABSX2,
@@ -1250,8 +1275,11 @@ always @(posedge clk or posedge reset)
RTS5 : state <= FETCH;
BRA0 : state <= cond_true ? BRA1 : DECODE;
BRA1 : state <= (CO ^ backwards) ? BRA2 : DECODE;
BRA2 : state <= DECODE;
BRA1 : state <= (CO ^ backwards) ? BRA2 : BRA5;
BRA2 : state <= (CO ^ backwards) ? BRA3 : BRA5;
BRA3 : state <= (CO ^ backwards) ? BRA4 : BRA5;
BRA4 : state <= BRA5;
BRA5 : state <= DECODE;
JMP0 : state <= JMP1;
JMP1 : state <= JMP2;
@@ -1284,14 +1312,16 @@ always @(posedge clk or posedge reset)
else if( RDY ) case( state )
BRA0 : SYNC <= !cond_true;
BRA1 : SYNC <= !(CO ^ backwards);
BRA2,
BRA2 : SYNC <= !(CO ^ backwards);
BRA3 : SYNC <= !(CO ^ backwards);
BRA4 : SYNC <= !(CO ^ backwards);
FETCH,
REG,
PUSH1,
PULL2,
RTI6,
JMP3,
BRA2 : SYNC <= 1'b1;
BRA5 : SYNC <= 1'b1;
default: SYNC <= 1'b0;
endcase