add absolute,x

sim/verilog6502_32bit_test.py

@@ -81,7 +81,8 @@ async def test_absolute(dut):
 
     write_dword(0xfffffff4, 0x200)
 
-    # lda #$abcd1234
+    # lda $abcd1234
+    # sta $50515253
     # wai
     write_bytes(0x200, [0xad, 0x34, 0x12, 0xcd, 0xab])
     write_bytes(0x205, [0x8d, 0x53, 0x52, 0x51, 0x50])
@@ -117,7 +118,77 @@ async def test_absolute(dut):
         (0x00000208, False, None),            # Read address byte 2
         (0x00000209, False, None),            # Read address byte 3
         (0x50515253, True, 0x55),             # Write to absolute address
-
+    ]
+
+    for expected_output in expected_cpu_outputs:
+        await RisingEdge(dut.clk)
+
+        if expected_output:
+            expected_addr, expected_we, expected_do = expected_output
+            dut_addr = int(dut.AB.value)
+            dut_we = bool(dut.WE.value)
+            dut_do = int(dut.DO.value)
+
+            assert dut_addr == expected_addr
+            assert dut_we == expected_we
+
+            if dut_we:
+                assert dut_do == expected_do
+
+@cocotb.test
+async def test_absolute_x(dut):
+    cocotb.start_soon(Clock(dut.clk, CLK_PERIOD, unit="ns").start())
+    cocotb.start_soon(handle_memory(dut))
+
+    write_dword(0xfffffff4, 0x200)
+
+    # ldx #1
+    # lda $abcd1234,x
+    # inx
+    # sta $01020304,x
+    # wai
+    write_bytes(0x200, [0xa2, 0x01])
+    write_bytes(0x202, [0xbd, 0x34, 0x12, 0xcd, 0xab])
+    write_bytes(0x207, [0xe8])
+    write_bytes(0x208, [0x9d, 0x04, 0x03, 0x02, 0x01])
+
+    write_byte(0x20d, 0xcb)
+    write_byte(0xabcd1235, 0xaa)
+
+    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 #1
+        (0x00000201, False, None),            # Immediate
+        (0x00000202, False, None),            # ldx $abcd1234,x
+        (0x00000203, False, None),            # addr 0
+        (0x00000204, False, None),            # addr 1
+        (0x00000205, False, None),            # addr 2
+        (0x00000206, False, None),            # addr 3
+        (0xabcd1235, False, None),            # Read from address
+        (0x00000207, False, None),            # inx
+        (0x00000208, False, None),            # sta $01020304,x
+        (0x00000208, False, None),            # store reg
+        (0x00000209, False, None),            # addr 0
+        (0x0000020a, False, None),            # addr 1
+        (0x0000020b, False, None),            # addr 2
+        (0x0000020c, False, None),            # addr 3
+        (0x01020306, False, None),            # Write to address
+        (0x01020306, True, 0xaa),             # Write to address
     ]
 
     for expected_output in expected_cpu_outputs:

src/cpu_65c02.v

@@ -268,7 +268,9 @@ parameter
     JMP2   = 6'd57, // TODO
     JMP3   = 6'd58, // TODO
     ABS2   = 6'd59, // TODO
-    ABS3   = 6'd60; // TODO
+    ABS3   = 6'd60, // TODO
+    ABSX3  = 6'd61, // TODO
+    ABSX4  = 6'd62; // TODO
 
 `ifdef SIM
 
@@ -291,6 +293,8 @@ always @*
             ABSX0:  statename = "ABSX0";
             ABSX1:  statename = "ABSX1";
             ABSX2:  statename = "ABSX2";
+            ABSX3:  statename = "ABSX3";
+            ABSX4:  statename = "ABSX4";
             IND0:   statename = "IND0";
             INDX0:  statename = "INDX0";
             INDX1:  statename = "INDX1";
@@ -396,6 +400,8 @@ always @*
         JMPIX0,
         JMPIX2,
         ABSX0,
+        ABSX1,
+        ABSX2,
         FETCH,
         BRA0,
         BRA2,
@@ -433,7 +439,7 @@ parameter
 always @*
     case( state )
         JMPIX1,
-        ABSX1,
+        ABSX3,
         INDX3,
         INDY2,
         JMP3,
@@ -444,7 +450,7 @@ always @*
         BRA2,
         INDY3,
         JMPIX2,
-        ABSX2:          AB = { ADD, ABR[7:0] }; // TODO
+        ABSX4:          AB = { ADD, ABR[23:0] }; // TODO
 
         BRA1:           AB = { ABR[15:8], ADD }; // TODO
 
@@ -540,7 +546,7 @@ always @*
 
         INDX3,  // only if doing a STA, STX or STY
         INDY3,
-        ABSX2,
+        ABSX4,
         ABS3,
         ZPX1,
         ZP0:     WE = store;
@@ -821,7 +827,9 @@ always @*
         INDY2,
         BRA1,
         JMPIX1,
-        ABSX1:  CI = CO;
+        ABSX1,  
+        ABSX2,
+        ABSX3: CI = CO;
 
         DECODE,
         ABS3:   CI = 1'bx;
@@ -1047,8 +1055,10 @@ always @(posedge clk or posedge reset)
         ABS3    : state <= write_back ? READ : FETCH;
 
         ABSX0   : state <= ABSX1;
-        ABSX1   : state <= (CO | store | write_back) ? ABSX2 : FETCH;
-        ABSX2   : state <= write_back ? READ : FETCH;
+        ABSX1   : state <= ABSX2;
+        ABSX2   : state <= ABSX3;
+        ABSX3   : state <= (CO | store | write_back) ? ABSX4 : FETCH;
+        ABSX4   : state <= write_back ? READ : FETCH;
 
         JMPIX0  : state <= JMPIX1;
         JMPIX1  : state <= CO ? JMPIX2 : JMP0;