From 2338d4c720089ae13d74467275b2f879faf02426 Mon Sep 17 00:00:00 2001
From: Byron Lathi <byron@byronlathi.com>
Date: Tue, 28 Apr 2026 22:17:42 -0700
Subject: [PATCH] Add some more tests

---
 sim/verilog6502_32bit_test.py | 81 ++++++++++++++++++++++++++++++++++-
 1 file changed, 80 insertions(+), 1 deletion(-)

diff --git a/sim/verilog6502_32bit_test.py b/sim/verilog6502_32bit_test.py
index 375acca..86cb441 100644
--- a/sim/verilog6502_32bit_test.py
+++ b/sim/verilog6502_32bit_test.py
@@ -2,10 +2,13 @@ import cocotb
 from cocotb.handle import Immediate
 
 from cocotb.clock import Clock
-from cocotb.triggers import Timer, RisingEdge
+from cocotb.triggers import Timer, RisingEdge, FallingEdge
 
 from collections import defaultdict
 
+import struct
+import random
+
 CLK_PERIOD = 5
 
 memory = defaultdict(int)
@@ -471,3 +474,79 @@ async def test_indirect_indexed(dut):
     ]
 
     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())
+    cocotb.start_soon(handle_memory(dut))
+
+    write_dword(0xfffffff4, 0x200)
+
+
+    def zp_indirect():
+        value = random.randint(0,255)
+        address = random.randint(0x300, 0xffffffff)
+
+        address_le = struct.pack("<I", address)
+
+        # lda #$0
+        # adc ($00)
+        # wai
+        write_bytes(0x200, [0xa9, 0x00, 0x72, 0x00, 0xcb])
+
+        write_bytes(0x00, address_le)
+        write_byte(address, value)
+
+        return value
+    
+    def absolute():
+        value = random.randint(0,255)
+        address = random.randint(0x300, 0xffffffff)
+
+        address_le = struct.pack("<I", address)
+
+        # lda $#0
+        # adc $address
+        # wai
+
+        write_bytes(0x200, [0xa9, 0x00, 0x6d])
+        write_bytes(0x203, address_le)
+        write_bytes(0x207, [0xcb])
+
+        write_byte(address, value)
+
+        return value
+
+    def indirect_x():
+        value = random.randint(0,255)
+        address = random.randint(0x300, 0xffffff00)
+        x_offset = random.randint(0,250)
+
+        address_le = struct.pack("<I", address)
+
+        # lda #$0
+        # ldx #x_offset
+        # adc ($00,x)
+        # wai
+
+        write_bytes(0x200, [0xa9, 0x00, 0xa2, x_offset, 0x61, 0x00, 0xcb])
+        write_bytes(x_offset, address_le)
+        write_byte(address, value)
+
+        return value
+
+    tests = [zp_indirect, absolute, indirect_x]
+
+    for test in tests:
+        value = test()
+
+        dut.RDY.value = Immediate(1)
+
+        dut.reset.value = Immediate(1)
+        for _ in range(10):
+            await RisingEdge(dut.clk)
+        dut.reset.value = 0
+
+        await FallingEdge(dut.RDY_O)
+
+        assert value == int(dut.A.value)
\ No newline at end of file