From ec311c879ea26d0a36cb5b885cc6b28c5dd19584 Mon Sep 17 00:00:00 2001
From: Mike Naberezny <mike@naberezny.com>
Date: Wed, 22 Jan 2014 22:56:02 -0800
Subject: [PATCH] Remove page wrap bug from JMP indirect on 65C02

---
 py65/devices/mpu65c02.py            |  5 +++++
 py65/tests/devices/test_mpu6502.py  | 27 ++++++++++++++++-----------
 py65/tests/devices/test_mpu65c02.py | 11 +++++++++++
 3 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/py65/devices/mpu65c02.py b/py65/devices/mpu65c02.py
index ee0b000..ad07605 100644
--- a/py65/devices/mpu65c02.py
+++ b/py65/devices/mpu65c02.py
@@ -279,6 +279,11 @@ class MPU(mpu6502.MPU):
     def inst_0x3a(self):
         self.opDECR(None)
 
+    @instruction(name="JMP", mode="ind", cycles=6)
+    def inst_0x6c(self):
+        ta = self.WordAt(self.pc)
+        self.pc = self.WordAt(ta)
+
     @instruction(name="JMP", mode="iax", cycles=6)
     def inst_0x7c(self):
         self.pc = self.WordAt(self.IndirectAbsXAddr())
diff --git a/py65/tests/devices/test_mpu6502.py b/py65/tests/devices/test_mpu6502.py
index 9c63b12..50270d6 100644
--- a/py65/tests/devices/test_mpu6502.py
+++ b/py65/tests/devices/test_mpu6502.py
@@ -2648,16 +2648,18 @@ class Common6502Tests:
         self.assertEqual(0x80, mpu.y)
         self.assertEqual(mpu.NEGATIVE, mpu.p & mpu.NEGATIVE)
 
-    # JMP
+    # JMP Absolute
 
-    def test_jmp_jumps_to_absolute_address(self):
+    def test_jmp_abs_jumps_to_absolute_address(self):
         mpu = self._make_mpu()
         # $0000 JMP $ABCD
         self._write(mpu.memory, 0x0000, (0x4C, 0xCD, 0xAB))
         mpu.step()
         self.assertEqual(0xABCD, mpu.pc)
 
-    def test_jmp_jumps_to_indirect_address(self):
+    # JMP Indirect
+
+    def test_jmp_ind_jumps_to_indirect_address(self):
         mpu = self._make_mpu()
         # $0000 JMP ($ABCD)
         self._write(mpu.memory, 0x0000, (0x6C, 0x00, 0x02))
@@ -5669,6 +5671,17 @@ class MPUTests(unittest.TestCase, Common6502Tests):
         self.assertEqual(mpu.BREAK, mpu.p & mpu.BREAK)
         self.assertEqual(0, mpu.p & mpu.DECIMAL)
 
+    # JMP Indirect
+
+    def test_jmp_jumps_to_address_with_page_wrap_bug(self):
+        mpu = self._make_mpu()
+        mpu.memory[0x00ff] = 0
+        # $0000 JMP ($00)
+        self._write(mpu.memory, 0, (0x6c, 0xff, 0x00))
+        mpu.step()
+        self.assertEqual(0x6c00, mpu.pc)
+        self.assertEqual(5, mpu.processorCycles)
+
     # Test page wrapping
 
     def test_zeropage_indexed_ind_wrap(self):
@@ -5709,14 +5722,6 @@ class MPUTests(unittest.TestCase, Common6502Tests):
         mpu.step()
         self.assertEqual(0x31, mpu.a)
 
-    def test_indirect_wrap(self):
-        mpu = self._make_mpu()
-        mpu.memory[0x00ff] = 0
-        # $0000 JMP ($00)
-        self._write(mpu.memory, 0, (0x6c, 0xff, 0x00))
-        mpu.step()
-        self.assertEqual(0x6c00, mpu.pc)
-
     def _get_target_class(self):
         return py65.devices.mpu6502.MPU
 
diff --git a/py65/tests/devices/test_mpu65c02.py b/py65/tests/devices/test_mpu65c02.py
index 7133801..bd088fe 100644
--- a/py65/tests/devices/test_mpu65c02.py
+++ b/py65/tests/devices/test_mpu65c02.py
@@ -475,6 +475,17 @@ class MPUTests(unittest.TestCase, Common6502Tests):
         self.assertEqual(mpu.NEGATIVE, mpu.p & mpu.NEGATIVE)
         self.assertEqual(0, mpu.p & mpu.ZERO)
 
+    # JMP Indirect
+
+    def test_jmp_ind_does_not_have_page_wrap_bug(self):
+        mpu = self._make_mpu()
+        self._write(mpu.memory, 0x10FF, (0xCD, 0xAB))
+        # $0000 JMP ($10FF)
+        self._write(mpu.memory, 0, (0x6c, 0xFF, 0x10))
+        mpu.step()
+        self.assertEqual(0xABCD, mpu.pc)
+        self.assertEqual(6, mpu.processorCycles)
+
     # JMP Indirect Absolute X-Indexed
 
     def test_jmp_iax_jumps_to_address(self):