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Added 65C02 instruction SBC (ZP).

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This commit is contained in:
Mike Naberezny 2009-04-08 19:21:54 -07:00
parent 97c024ae0d
commit 51638732a7
2 changed files with 72 additions and 1 deletions
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5
src/py65/devices/mpu65c02.py
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@ -142,3 +142,8 @@ class MPU(NMOS6502):
self.opTRB(self.AbsoluteAddr)
self.pc += 2
@instruction(name="SBC", mode="zpi", cycles=5)
def if2(self):
self.opSBC(self.ZeroPageIndirectAddr)
self.pc += 1

68
src/py65/tests/devices/test_mpu65c02.py
View File

@ -280,7 +280,73 @@ class MPUTests(unittest.TestCase, Common6502Tests):
self.assertEquals(0x00, mpu.memory[0xFEED])
self.assertEquals(0x00, mpu.a)
self.assertEquals(flags, mpu.flags)
# SBC Zero Page, Indirect
def test_sbc_zp_indirect_all_zeros_and_no_borrow_is_zero(self):
mpu = self._make_mpu()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x00
self._write(mpu.memory, 0x0000, (0xF2, 0x10)) #=> SBC ($10)
self._write(mpu.memory, 0x0010, (0xED, 0xFE)) #=> Vector to $FEED
mpu.memory[0xFEED] = 0x00
mpu.step()
self.assertEquals(0x0002, mpu.pc)
self.assertEquals(5, mpu.processorCycles)
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_indirect_downto_zero_no_borrow_sets_z_clears_n(self):
mpu = self._make_mpu()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags |= mpu.CARRY # borrow = 0
mpu.a = 0x01
self._write(mpu.memory, 0x0000, (0xF2, 0x10)) #=> SBC ($10)
self._write(mpu.memory, 0x0010, (0xED, 0xFE)) #=> Vector to $FEED
mpu.memory[0xFEED] = 0x01
mpu.step()
self.assertEquals(0x0002, mpu.pc)
self.assertEquals(5, mpu.processorCycles)
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_indirect_downto_zero_with_borrow_sets_z_clears_n(self):
mpu = self._make_mpu()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x01
self._write(mpu.memory, 0x0000, (0xF2, 0x10)) #=> SBC ($10)
self._write(mpu.memory, 0x0010, (0xED, 0xFE)) #=> Vector to $FEED
mpu.memory[0xFEED] = 0x00
mpu.step()
self.assertEquals(0x0002, mpu.pc)
self.assertEquals(5, mpu.processorCycles)
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_indirect_downto_four_with_borrow_clears_z_n(self):
mpu = self._make_mpu()
mpu.flags &= ~(mpu.DECIMAL)
mpu.flags &= ~(mpu.CARRY) # borrow = 1
mpu.a = 0x07
self._write(mpu.memory, 0x0000, (0xF2, 0x10)) #=> SBC ($10)
self._write(mpu.memory, 0x0010, (0xED, 0xFE)) #=> Vector to $FEED
mpu.memory[0xFEED] = 0x02
mpu.step()
self.assertEquals(0x0002, mpu.pc)
self.assertEquals(5, mpu.processorCycles)
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)
# STZ Zero Page
def test_stz_zp_stores_zero(self):