From c650a0dc0cd9235207ecbae168af6189d1a2905d Mon Sep 17 00:00:00 2001
From: Mike Naberezny <mike@maintainable.com>
Date: Sun, 20 Jul 2008 04:24:45 +0000
Subject: [PATCH] Fixed bug in EOR and added unit tests.

---
 TODO.txt    |   1 -
 mpu.py      |   4 +-
 mpu_test.py | 212 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 213 insertions(+), 4 deletions(-)

diff --git a/TODO.txt b/TODO.txt
index 85afbc8..53bd5ed 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -4,6 +4,5 @@ Instructions needing unit tests:
   cpx
   cpy
   dec
-  eor
   inc
   sbc
diff --git a/mpu.py b/mpu.py
index d2e6a25..59e7fd9 100644
--- a/mpu.py
+++ b/mpu.py
@@ -240,8 +240,8 @@ class MPU:
     self.RAM[addr] = tbyte & 0xFF
 
   def opEOR(self, x):
-    self.a^=self.ByteAt(x())
-    self.FlagsNZ(a)
+    self.a ^= self.ByteAt(x())
+    self.FlagsNZ(self.a)
 
   def opADC(self, x):
     data=self.ByteAt(x())
diff --git a/mpu_test.py b/mpu_test.py
index 0016920..f3e10ca 100644
--- a/mpu_test.py
+++ b/mpu_test.py
@@ -1279,7 +1279,217 @@ class MPUTests(unittest.TestCase):
     self.assertEquals(0x0001, mpu.pc)
     self.assertEquals(0x00, mpu.y)
     self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
-    
+  
+  # EOR Absolute
+  
+  def test_eor_absolute_flips_bits_over_setting_z_flag(self):
+    mpu = MPU()
+    mpu.a = 0xFF
+    mpu.memory[0x0000:0x0002] = (0x4D, 0xCD, 0xAB)
+    mpu.memory[0xABCD] = 0xFF
+    mpu.step()
+    self.assertEquals(0x0003, mpu.pc)
+    self.assertEquals(0x00, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0xABCD])
+    self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
+
+  def test_eor_absolute_flips_bits_over_setting_n_flag(self):
+    mpu = MPU()
+    mpu.a = 0x00
+    mpu.memory[0x0000:0x0002] = (0x4D, 0xCD, 0xAB)
+    mpu.memory[0xABCD] = 0xFF
+    mpu.step()    
+    self.assertEquals(0x0003, mpu.pc)
+    self.assertEquals(0xFF, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0xABCD])
+    self.assertEquals(mpu.NEGATIVE, mpu.flags & mpu.NEGATIVE)
+    self.assertEquals(0, mpu.flags & mpu.ZERO)
+
+  # EOR Zero Page
+  
+  def test_eor_zp_flips_bits_over_setting_z_flag(self):
+    mpu = MPU()
+    mpu.a = 0xFF
+    mpu.memory[0x0000:0x0001] = (0x45, 0x10)
+    mpu.memory[0x0010] = 0xFF
+    mpu.step()
+    self.assertEquals(0x0002, mpu.pc)
+    self.assertEquals(0x00, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0x0010])
+    self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
+
+  def test_eor_zp_flips_bits_over_setting_n_flag(self):
+    mpu = MPU()
+    mpu.a = 0x00
+    mpu.memory[0x0000:0x0002] = (0x45, 0x10)
+    mpu.memory[0x0010] = 0xFF
+    mpu.step()    
+    self.assertEquals(0x0002, mpu.pc)
+    self.assertEquals(0xFF, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0x0010])
+    self.assertEquals(mpu.NEGATIVE, mpu.flags & mpu.NEGATIVE)
+    self.assertEquals(0, mpu.flags & mpu.ZERO)
+
+  # EOR Immediate
+  
+  def test_eor_immediate_flips_bits_over_setting_z_flag(self):
+    mpu = MPU()
+    mpu.a = 0xFF
+    mpu.memory[0x0000:0x0001] = (0x49, 0xFF)
+    mpu.step()
+    self.assertEquals(0x0002, mpu.pc)
+    self.assertEquals(0x00, mpu.a)
+    self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
+
+  def test_eor_immediate_flips_bits_over_setting_n_flag(self):
+    mpu = MPU()
+    mpu.a = 0x00
+    mpu.memory[0x0000:0x0002] = (0x49, 0xFF)
+    mpu.step()    
+    self.assertEquals(0x0002, mpu.pc)
+    self.assertEquals(0xFF, mpu.a)
+    self.assertEquals(mpu.NEGATIVE, mpu.flags & mpu.NEGATIVE)
+    self.assertEquals(0, mpu.flags & mpu.ZERO)
+
+  # EOR Absolute, X-Indexed
+  
+  def test_eor_absolute_x_indexed_flips_bits_over_setting_z_flag(self):
+    mpu = MPU()
+    mpu.a = 0xFF
+    mpu.x = 0x03
+    mpu.memory[0x0000:0x0002] = (0x5D, 0xCD, 0xAB)
+    mpu.memory[0xABCD + mpu.x] = 0xFF
+    mpu.step()
+    self.assertEquals(0x0003, mpu.pc)
+    self.assertEquals(0x00, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0xABCD + mpu.x])
+    self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
+
+  def test_eor_absolute_x_indexed_flips_bits_over_setting_n_flag(self):
+    mpu = MPU()
+    mpu.a = 0x00
+    mpu.x = 0x03
+    mpu.memory[0x0000:0x0002] = (0x5D, 0xCD, 0xAB)
+    mpu.memory[0xABCD + mpu.x] = 0xFF
+    mpu.step()    
+    self.assertEquals(0x0003, mpu.pc)
+    self.assertEquals(0xFF, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0xABCD + mpu.x])
+    self.assertEquals(mpu.NEGATIVE, mpu.flags & mpu.NEGATIVE)
+    self.assertEquals(0, mpu.flags & mpu.ZERO)
+
+  # EOR Absolute, Y-Indexed
+  
+  def test_eor_absolute_y_indexed_flips_bits_over_setting_z_flag(self):
+    mpu = MPU()
+    mpu.a = 0xFF
+    mpu.y = 0x03
+    mpu.memory[0x0000:0x0002] = (0x59, 0xCD, 0xAB)
+    mpu.memory[0xABCD + mpu.y] = 0xFF
+    mpu.step()
+    self.assertEquals(0x0003, mpu.pc)
+    self.assertEquals(0x00, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0xABCD + mpu.y])
+    self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
+
+  def test_eor_absolute_y_indexed_flips_bits_over_setting_n_flag(self):
+    mpu = MPU()
+    mpu.a = 0x00
+    mpu.y = 0x03
+    mpu.memory[0x0000:0x0002] = (0x59, 0xCD, 0xAB)
+    mpu.memory[0xABCD + mpu.y] = 0xFF
+    mpu.step()    
+    self.assertEquals(0x0003, mpu.pc)
+    self.assertEquals(0xFF, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0xABCD + mpu.y])
+    self.assertEquals(mpu.NEGATIVE, mpu.flags & mpu.NEGATIVE)
+    self.assertEquals(0, mpu.flags & mpu.ZERO)
+
+  # EOR Indirect, Indexed (X)
+
+  def test_eor_indirect_indexed_x_flips_bits_over_setting_z_flag(self):
+    mpu = MPU()
+    mpu.a = 0xFF
+    mpu.x = 0x03
+    mpu.memory[0x0000:0x0001] = (0x41, 0x10) #=> EOR ($0010,X)
+    mpu.memory[0x0013:0x0014] = (0xCD, 0xAB) #=> Vector to $ABCD
+    mpu.memory[0xABCD] = 0xFF
+    mpu.step()
+    self.assertEquals(0x0002, mpu.pc)
+    self.assertEquals(0x00, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0xABCD])
+    self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
+
+  def test_eor_indirect_indexed_x_flips_bits_over_setting_n_flag(self):
+    mpu = MPU()
+    mpu.a = 0x00
+    mpu.x = 0x03
+    mpu.memory[0x0000:0x0001] = (0x41, 0x10) #=> EOR ($0010,X)
+    mpu.memory[0x0013:0x0014] = (0xCD, 0xAB) #=> Vector to $ABCD
+    mpu.memory[0xABCD] = 0xFF
+    mpu.step()
+    self.assertEquals(0x0002, mpu.pc)
+    self.assertEquals(0xFF, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0xABCD])
+    self.assertEquals(mpu.NEGATIVE, mpu.flags & mpu.NEGATIVE)
+    self.assertEquals(0, mpu.flags & mpu.ZERO)      
+
+  # EOR Indexed, Indirect (Y)
+  
+  def test_eor_indexed_indirect_y_flips_bits_over_setting_z_flag(self):
+    mpu = MPU()
+    mpu.a = 0xFF
+    mpu.y = 0x03
+    mpu.memory[0x0000:0x0001] = (0x51, 0x10) #=> EOR ($0010),Y
+    mpu.memory[0x0010:0x0011] = (0xCD, 0xAB) #=> Vector to $ABCD
+    mpu.memory[0xABCD + mpu.y] = 0xFF
+    mpu.step()
+    self.assertEquals(0x0002, mpu.pc)
+    self.assertEquals(0x00, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0xABCD + mpu.y])
+    self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)    
+
+  def test_eor_indexed_indirect_y_flips_bits_over_setting_n_flag(self):
+    mpu = MPU()
+    mpu.a = 0x00
+    mpu.y = 0x03
+    mpu.memory[0x0000:0x0001] = (0x51, 0x10) #=> EOR ($0010),Y
+    mpu.memory[0x0010:0x0011] = (0xCD, 0xAB) #=> Vector to $ABCD
+    mpu.memory[0xABCD + mpu.y] = 0xFF
+    mpu.step()
+    self.assertEquals(0x0002, mpu.pc)
+    self.assertEquals(0xFF, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0xABCD + mpu.y])
+    self.assertEquals(mpu.NEGATIVE, mpu.flags & mpu.NEGATIVE)
+    self.assertEquals(0, mpu.flags & mpu.ZERO)      
+
+  # EOR Zero Page, X-Indexed
+  
+  def test_eor_zp_x_indexed_flips_bits_over_setting_z_flag(self):
+    mpu = MPU()
+    mpu.a = 0xFF
+    mpu.x = 0x03
+    mpu.memory[0x0000:0x0001] = (0x55, 0x10)
+    mpu.memory[0x0010 + mpu.x] = 0xFF
+    mpu.step()
+    self.assertEquals(0x0002, mpu.pc)
+    self.assertEquals(0x00, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0x0010 + mpu.x])
+    self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
+
+  def test_eor_zp_x_indexed_flips_bits_over_setting_n_flag(self):
+    mpu = MPU()
+    mpu.a = 0x00
+    mpu.x = 0x03
+    mpu.memory[0x0000:0x0002] = (0x55, 0x10)
+    mpu.memory[0x0010 + mpu.x] = 0xFF
+    mpu.step()    
+    self.assertEquals(0x0002, mpu.pc)
+    self.assertEquals(0xFF, mpu.a)
+    self.assertEquals(0xFF, mpu.memory[0x0010 + mpu.x])
+    self.assertEquals(mpu.NEGATIVE, mpu.flags & mpu.NEGATIVE)
+    self.assertEquals(0, mpu.flags & mpu.ZERO)
+        
   # INX
 
   def test_inx_increments_x(self):