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Added unit tests for SBC.

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This commit is contained in:
Mike Naberezny 2009-02-26 20:30:58 -08:00
parent 22b46111b7
commit d860053ea3
2 changed files with 459 additions and 2 deletions
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1
TODO
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@ -2,7 +2,6 @@ Instructions needing unit tests:
cmp cmp
cpx cpx
cpy cpy
sbc
Better error messages when assembling fails. Better error messages when assembling fails.

460
src/py65/tests/test_mpu6502.py
View File

@ -3464,7 +3464,7 @@ class MPUTests(unittest.TestCase):
self.assertEquals(0xC004, mpu.pc) self.assertEquals(0xC004, mpu.pc)
self.assertEquals(0xFF, mpu.sp) self.assertEquals(0xFF, mpu.sp)
# SBC # SBC Absolute
def test_sbc_abs_all_zeros_and_no_borrow_is_zero(self): def test_sbc_abs_all_zeros_and_no_borrow_is_zero(self):
mpu = MPU() mpu = MPU()
@ -3518,6 +3518,464 @@ class MPUTests(unittest.TestCase):
self.assertEquals(0, mpu.flags & mpu.ZERO) self.assertEquals(0, mpu.flags & mpu.ZERO)
self.assertEquals(mpu.CARRY, mpu.CARRY) self.assertEquals(mpu.CARRY, mpu.CARRY)
# SBC Zero Page
def test_sbc_zp_all_zeros_and_no_borrow_is_zero(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x00
mpu.memory[0x0000:0x0001] = (0xE5, 0x10) #=> SBC $10
mpu.memory[0x0010] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_zp_downto_zero_no_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xE5, 0x10) #=> SBC $10
mpu.memory[0x0010] = 0x01
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_zp_downto_zero_with_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xE5, 0x10) #=> SBC $10
mpu.memory[0x0010] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_zp_downto_four_with_borrow_clears_z_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x07
mpu.memory[0x0000:0x0001] = (0xE5, 0x10) #=> SBC $10
mpu.memory[0x0010] = 0x02
mpu.step()
self.assertEquals(0x04, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(0, mpu.flags & mpu.ZERO)
self.assertEquals(mpu.CARRY, mpu.CARRY)
# SBC Immediate
def test_sbc_imm_all_zeros_and_no_borrow_is_zero(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x00
mpu.memory[0x0000:0x0001] = (0xE9, 0x00) #=> SBC #$00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_imm_downto_zero_no_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xE9, 0x01) #=> SBC #$01
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_imm_downto_zero_with_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xE9, 0x00) #=> SBC #$00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_imm_downto_four_with_borrow_clears_z_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x07
mpu.memory[0x0000:0x0001] = (0xE9, 0x02) #=> SBC #$02
mpu.step()
self.assertEquals(0x04, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(0, mpu.flags & mpu.ZERO)
self.assertEquals(mpu.CARRY, mpu.CARRY)
# SBC Absolute, X-Indexed
def test_sbc_abs_x_all_zeros_and_no_borrow_is_zero(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x00
mpu.memory[0x0000:0x0002] = (0xFD, 0xE0, 0xFE) #=> SBC $FEE0,X
mpu.x = 0x0D
mpu.memory[0xFEED] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_abs_x_downto_zero_no_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x01
mpu.memory[0x0000:0x0002] = (0xFD, 0xE0, 0xFE) #=> SBC $FEE0,X
mpu.x = 0x0D
mpu.memory[0xFEED] = 0x01
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_abs_x_downto_zero_with_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x01
mpu.memory[0x0000:0x0002] = (0xFD, 0xE0, 0xFE) #=> SBC $FEE0,X
mpu.x = 0x0D
mpu.memory[0xFEED] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_abs_x_downto_four_with_borrow_clears_z_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x07
mpu.memory[0x0000:0x0002] = (0xFD, 0xE0, 0xFE) #=> SBC $FEE0,X
mpu.x = 0x0D
mpu.memory[0xFEED] = 0x02
mpu.step()
self.assertEquals(0x04, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(0, mpu.flags & mpu.ZERO)
self.assertEquals(mpu.CARRY, mpu.CARRY)
# SBC Absolute, Y-Indexed
def test_sbc_abs_y_all_zeros_and_no_borrow_is_zero(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x00
mpu.memory[0x0000:0x0002] = (0xF9, 0xE0, 0xFE) #=> SBC $FEE0,Y
mpu.y = 0x0D
mpu.memory[0xFEED] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_abs_y_downto_zero_no_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x01
mpu.memory[0x0000:0x0002] = (0xF9, 0xE0, 0xFE) #=> SBC $FEE0,Y
mpu.y = 0x0D
mpu.memory[0xFEED] = 0x01
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_abs_y_downto_zero_with_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x01
mpu.memory[0x0000:0x0002] = (0xF9, 0xE0, 0xFE) #=> SBC $FEE0,Y
mpu.y = 0x0D
mpu.memory[0xFEED] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_abs_y_downto_four_with_borrow_clears_z_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x07
mpu.memory[0x0000:0x0002] = (0xF9, 0xE0, 0xFE) #=> SBC $FEE0,Y
mpu.y = 0x0D
mpu.memory[0xFEED] = 0x02
mpu.step()
self.assertEquals(0x04, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(0, mpu.flags & mpu.ZERO)
self.assertEquals(mpu.CARRY, mpu.CARRY)
# SBC Indirect, Indexed (X)
def test_sbc_ind_x_all_zeros_and_no_borrow_is_zero(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x00
mpu.memory[0x0000:0x0001] = (0xE1, 0x10) #=> SBC ($10,X)
mpu.memory[0x0013:0x0014] = (0xED, 0xFE) #=> Vector to $FEED
mpu.x = 0x03
mpu.memory[0xFEED] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_ind_x_downto_zero_no_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xE1, 0x10) #=> SBC ($10,X)
mpu.memory[0x0013:0x0014] = (0xED, 0xFE) #=> Vector to $FEED
mpu.x = 0x03
mpu.memory[0xFEED] = 0x01
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_ind_x_downto_zero_with_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xE1, 0x10) #=> SBC ($10,X)
mpu.memory[0x0013:0x0014] = (0xED, 0xFE) #=> Vector to $FEED
mpu.x = 0x03
mpu.memory[0xFEED] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_ind_x_downto_four_with_borrow_clears_z_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x07
mpu.memory[0x0000:0x0001] = (0xE1, 0x10) #=> SBC ($10,X)
mpu.memory[0x0013:0x0014] = (0xED, 0xFE) #=> Vector to $FEED
mpu.x = 0x03
mpu.memory[0xFEED] = 0x02
mpu.step()
self.assertEquals(0x04, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(0, mpu.flags & mpu.ZERO)
self.assertEquals(mpu.CARRY, mpu.CARRY)
def test_sbc_ind_x_all_zeros_and_no_borrow_is_zero(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x00
mpu.memory[0x0000:0x0001] = (0xE1, 0x10) #=> SBC ($10,X)
mpu.memory[0x0013:0x0014] = (0xED, 0xFE) #=> Vector to $FEED
mpu.x = 0x03
mpu.memory[0xFEED] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_ind_x_downto_zero_no_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xE1, 0x10) #=> SBC ($10,X)
mpu.memory[0x0013:0x0014] = (0xED, 0xFE) #=> Vector to $FEED
mpu.x = 0x03
mpu.memory[0xFEED] = 0x01
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_ind_x_downto_zero_with_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xE1, 0x10) #=> SBC ($10,X)
mpu.memory[0x0013:0x0014] = (0xED, 0xFE) #=> Vector to $FEED
mpu.x = 0x03
mpu.memory[0xFEED] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_ind_x_downto_four_with_borrow_clears_z_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x07
mpu.memory[0x0000:0x0001] = (0xE1, 0x10) #=> SBC ($10,X)
mpu.memory[0x0013:0x0014] = (0xED, 0xFE) #=> Vector to $FEED
mpu.x = 0x03
mpu.memory[0xFEED] = 0x02
mpu.step()
self.assertEquals(0x04, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(0, mpu.flags & mpu.ZERO)
self.assertEquals(mpu.CARRY, mpu.CARRY)
# SBC Indexed, Indirect (Y)
def test_sbc_ind_y_all_zeros_and_no_borrow_is_zero(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x00
mpu.y = 0x03
mpu.memory[0x0000:0x0001] = (0xF1, 0x10) #=> SBC ($10),Y
mpu.memory[0x0013:0x0014] = (0xED, 0xFE) #=> Vector to $FEED
mpu.memory[0xFEED + mpu.y] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_ind_y_downto_zero_no_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xF1, 0x10) #=> SBC ($10),Y
mpu.memory[0x0010:0x0011] = (0xED, 0xFE) #=> Vector to $FEED
mpu.memory[0xFEED + mpu.y] = 0x01
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_ind_y_downto_zero_with_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xF1, 0x10) #=> SBC ($10),Y
mpu.memory[0x0010:0x0011] = (0xED, 0xFE) #=> Vector to $FEED
mpu.memory[0xFEED + mpu.y] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_ind_y_downto_four_with_borrow_clears_z_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x07
mpu.memory[0x0000:0x0001] = (0xF1, 0x10) #=> SBC ($10),Y
mpu.memory[0x0010:0x0011] = (0xED, 0xFE) #=> Vector to $FEED
mpu.memory[0xFEED + mpu.y] = 0x02
mpu.step()
self.assertEquals(0x04, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(0, mpu.flags & mpu.ZERO)
self.assertEquals(mpu.CARRY, mpu.CARRY)
# SBC Zero Page, X-Indexed
def test_sbc_zp_x_all_zeros_and_no_borrow_is_zero(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x00
mpu.memory[0x0000:0x0001] = (0xF5, 0x10) #=> SBC $10,X
mpu.x = 0x0D
mpu.memory[0x001D] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_zp_x_downto_zero_no_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xF5, 0x10) #=> SBC $10,X
mpu.x = 0x0D
mpu.memory[0x001D] = 0x01
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_zp_x_downto_zero_with_borrow_sets_z_clears_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x01
mpu.memory[0x0000:0x0001] = (0xF5, 0x10) #=> SBC $10,X
mpu.x = 0x0D
mpu.memory[0x001D] = 0x00
mpu.step()
self.assertEquals(0x00, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(mpu.CARRY, mpu.CARRY)
self.assertEquals(mpu.ZERO, mpu.flags & mpu.ZERO)
def test_sbc_zp_x_downto_four_with_borrow_clears_z_n(self):
mpu = MPU()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x07
mpu.memory[0x0000:0x0001] = (0xF5, 0x10) #=> SBC $10,X
mpu.x = 0x0D
mpu.memory[0x001D] = 0x02
mpu.step()
self.assertEquals(0x04, mpu.a)
self.assertEquals(0, mpu.flags & mpu.NEGATIVE)
self.assertEquals(0, mpu.flags & mpu.ZERO)
self.assertEquals(mpu.CARRY, mpu.CARRY)
# SEC # SEC