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Add indirect indexed

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This commit is contained in:
Byron Lathi
2026-04-27 23:00:44 -07:00
parent dfe27d4ec7
commit 2a9af9e9dc
2 changed files with 93 additions and 15 deletions
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72
sim/verilog6502_32bit_test.py
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@@ -401,5 +401,73 @@ async def test_indexed_indirect(dut):
(0xabcdbef2, False, None), # store takes extra cycle (0xabcdbef2, False, None), # store takes extra cycle
(0xabcdbef2, True, 0xAB), # write data (0xabcdbef2, True, 0xAB), # write data
] ]
await check_instruction_sequence(dut, expected_cpu_outputs) await check_instruction_sequence(dut, expected_cpu_outputs)
@cocotb.test
async def test_indirect_indexed(dut):
cocotb.start_soon(Clock(dut.clk, CLK_PERIOD, unit="ns").start())
cocotb.start_soon(handle_memory(dut))
write_dword(0xfffffff4, 0x200)
# ldx #4
# lda ($04,x)
# inc
# ldx #8
# sta ($04,x)
write_bytes(0x200, [0xa2, 0x04])
write_bytes(0x202, [0xa1, 0x04])
write_bytes(0x204, [0x1a])
write_bytes(0x205, [0xa2, 0x08])
write_bytes(0x207, [0x81, 0x04])
write_byte(0x209, 0xcb)
write_dword(0x08, 0xfeedf00d)
write_dword(0x0c, 0xf00d600d)
write_byte(0xfeedf00d, 0x69)
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,
(0x00000200, False, None), # ldx #4
(0x00000201, False, None), # Immediate
(0x00000202, False, None), # lda ($04,x)
(0x00000203, False, None), # ZP index
(0x00000004, False, None), # Compute ZP index
(0x00000008, False, None), # zp addr 0
(0x00000009, False, None), # zp addr 1
(0x0000000a, False, None), # zp addr 2
(0x0000000b, False, None), # zp addr 3
(0xfeedf00d, False, None), # fetch data
(0x00000204, False, None), # iny
(0x00000205, False, None), # iny
(0x00000205, False, None), # inc
(0x00000206, False, None), # inc
(0x00000207, False, None), # sta ($04),y
(0x00000208, False, None), # ZP index
(0x00000004, False, None), # Compute ZP index
(0x0000000c, False, None), # zp addr 0
(0x0000000d, False, None), # zp addr 1
(0x0000000e, False, None), # zp addr 2
(0x0000000f, False, None), # zp addr 3
(0xf00d600d, True, 0x6a), # write data
]
await check_instruction_sequence(dut, expected_cpu_outputs)

36
src/cpu_65c02.v
View File

@@ -226,7 +226,7 @@ parameter
INDX0 = 7'd14, // (ZP,X) - fetch ZP address, and send to ALU (+X) INDX0 = 7'd14, // (ZP,X) - fetch ZP address, and send to ALU (+X)
INDX1 = 7'd15, // (ZP,X) - fetch LSB at ZP+X, calculate ZP+X+1 INDX1 = 7'd15, // (ZP,X) - fetch LSB at ZP+X, calculate ZP+X+1
INDX2 = 7'd16, // (ZP,X) - fetch MSB at ZP+X+1 INDX2 = 7'd16, // (ZP,X) - fetch MSB at ZP+X+1
INDX3 = 7'd17, // (ZP,X) - fetch data INDX5 = 7'd17, // (ZP,X) - fetch data
INDY0 = 7'd18, // (ZP),Y - fetch ZP address INDY0 = 7'd18, // (ZP),Y - fetch ZP address
INDY1 = 7'd19, // (ZP),Y - fetch at ZP+1, and send byte 0 to ALU (+Y) INDY1 = 7'd19, // (ZP),Y - fetch at ZP+1, and send byte 0 to ALU (+Y)
INDY2 = 7'd20, // (ZP),Y - fetch at ZP+2, and send byte 1 to ALU (+Carry) INDY2 = 7'd20, // (ZP),Y - fetch at ZP+2, and send byte 1 to ALU (+Carry)
@@ -277,7 +277,10 @@ parameter
JMPI2 = 7'd65, // TODO JMPI2 = 7'd65, // TODO
JMPI3 = 7'd66, // TODO JMPI3 = 7'd66, // TODO
INDY3 = 7'd67, // (ZP),Y - fetch at ZP+3, and send byte 2 to ALU (+Carry) INDY3 = 7'd67, // (ZP),Y - fetch at ZP+3, and send byte 2 to ALU (+Carry)
INDY4 = 7'd68; // (ZP),Y - fetch data, and send byte 3 to ALU (+Carry) INDY4 = 7'd68, // (ZP),Y - fetch data, and send byte 3 to ALU (+Carry)
INDX3 = 7'd69, // (ZP,X) - fetch addr 2 at ZP+X+2
INDX4 = 7'd70; // (ZP,X) - fetch addr 3 at ZP+X+3
`ifdef SIM `ifdef SIM
@@ -307,6 +310,8 @@ always @*
INDX1: statename = "INDX1"; INDX1: statename = "INDX1";
INDX2: statename = "INDX2"; INDX2: statename = "INDX2";
INDX3: statename = "INDX3"; INDX3: statename = "INDX3";
INDX4: statename = "INDX4";
INDX5: statename = "INDX5";
INDY0: statename = "INDY0"; INDY0: statename = "INDY0";
INDY1: statename = "INDY1"; INDY1: statename = "INDY1";
INDY2: statename = "INDY2"; INDY2: statename = "INDY2";
@@ -458,7 +463,7 @@ always @*
case( state ) case( state )
JMPIX3, JMPIX3,
ABSX3, ABSX3,
INDX3, INDX5,
JMP3, JMP3,
JMPI3, JMPI3,
RTI4, RTI4,
@@ -489,10 +494,10 @@ always @*
BRK4: AB = { 16'h0, STACKPAGE, ADD }; BRK4: AB = { 16'h0, STACKPAGE, ADD };
INDX1, INDX1,
ZPX1, ZPX1: AB = { ZEROPAGE, ADD };
INDX2: AB = { ZEROPAGE, ADD };
ZP0, ZP0,
INDX0,
INDY0: AB = { ZEROPAGE, DIMUX }; INDY0: AB = { ZEROPAGE, DIMUX };
REG, REG,
@@ -500,6 +505,9 @@ always @*
INDY1, INDY1,
INDY2, INDY2,
INDY3, INDY3,
INDX2,
INDX3,
INDX4,
WRITE: AB = ABR; WRITE: AB = ABR;
INDY4: AB = {DIMUX, ADD, alu_sr_0, alu_sr_1}; INDY4: AB = {DIMUX, ADD, alu_sr_0, alu_sr_1};
@@ -528,7 +536,10 @@ always @* begin
case( state ) case( state )
INDY0, INDY0,
INDY1, INDY1,
INDY2: abr_inc = 1; INDY2,
INDX1,
INDX2,
INDX3: abr_inc = 1;
default: abr_inc = 0; default: abr_inc = 0;
endcase endcase
end end
@@ -578,7 +589,7 @@ always @*
PUSH1, PUSH1,
WRITE: WE = 1; WRITE: WE = 1;
INDX3, // only if doing a STA, STX or STY INDX5, // only if doing a STA, STX or STY
INDY5, INDY5,
ABSX4, ABSX4,
ABS3, ABS3,
@@ -786,8 +797,7 @@ always @*
BRK1, BRK1,
BRK2, BRK2,
BRK3, BRK3,
BRK4, BRK4: AI = ADD;
INDX1: AI = ADD;
REG, REG,
ZPX0, ZPX0,
@@ -829,7 +839,6 @@ always @*
RTI0, RTI0,
RTI1, RTI1,
RTI2, RTI2,
INDX1,
REG, REG,
JSR0, JSR0,
JSR1, JSR1,
@@ -882,8 +891,7 @@ always @*
RTI2, RTI2,
RTS0, RTS0,
RTS1, RTS1,
INDY0, INDY0: CI = 1;
INDX1: CI = 1;
default: CI = 0; default: CI = 0;
endcase endcase
@@ -1105,7 +1113,9 @@ always @(posedge clk or posedge reset)
INDX0 : state <= INDX1; INDX0 : state <= INDX1;
INDX1 : state <= INDX2; INDX1 : state <= INDX2;
INDX2 : state <= INDX3; INDX2 : state <= INDX3;
INDX3 : state <= FETCH; INDX3 : state <= INDX4;
INDX4 : state <= INDX5;
INDX5 : state <= FETCH;
INDY0 : state <= INDY1; INDY0 : state <= INDY1;
INDY1 : state <= INDY2; INDY1 : state <= INDY2;