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https://github.com/mnaberez/py65.git
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Clean up code, tests still equally working (but still not yet the
klaus 65C02 one)
This commit is contained in:
kris
parent
254b2fb167
commit
0e7066a4e1
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@ -318,36 +318,43 @@ class MPU:
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adjust1 = 6
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decimalcarry = 1
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# the ALU outputs are not decimally adjusted
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# The ALU outputs are not yet decimally adjusted
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nibble0 = nibble0 & 0xf
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nibble1 = nibble1 & 0xf
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aluresult = (nibble1 << 4) + nibble0
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# the final A contents will be decimally adjusted
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# Partial result with only low nibble decimally adjusted
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nibble0 = (nibble0 + adjust0) & 0xf
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halfadjresult = (nibble1 << 4) + nibble0
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# the final A contents has both nibbles decimally adjusted
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nibble1 = (nibble1 + adjust1) & 0xf
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adjresult = (nibble1 << 4) + nibble0
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self.p &= ~(self.CARRY | self.OVERFLOW | self.NEGATIVE | self.ZERO)
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if flags_use_adjusted_result: # 65C02 and 65816
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if adjresult == 0:
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self.p |= self.ZERO
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else:
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self.p |= adjresult & self.NEGATIVE
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if decimalcarry == 1:
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self.p |= self.CARRY
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if (~(self.a ^ data) & (self.a ^ aluresult)) & self.NEGATIVE:
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self.p |= self.OVERFLOW
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# Z and N use adjusted (i.e. decimal) result
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zerores = adjresult
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negativeres = adjresult
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else: # 6502
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# Z uses unadjusted (i.e. binary) ALU result
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zerores = aluresult
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# N effectively uses ALU result with only low nibble
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# decimally adjusted - but see here for what is really going on
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# https://atariage.com/forums/topic/163876-flags-on-decimal-mode-on-the-nmos-6502/
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negativeres = halfadjresult
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if zerores == 0:
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self.p |= self.ZERO
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else:
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if aluresult == 0:
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self.p |= self.ZERO
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else:
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self.p |= aluresult & self.NEGATIVE
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if decimalcarry == 1:
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self.p |= self.CARRY
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if (~(self.a ^ data) & (self.a ^ aluresult)) & self.NEGATIVE:
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self.p |= self.OVERFLOW
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self.p |= negativeres & self.NEGATIVE
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if decimalcarry == 1:
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self.p |= self.CARRY
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if (~(self.a ^ data) & (self.a ^ aluresult)) & self.NEGATIVE:
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self.p |= self.OVERFLOW
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self.a = adjresult
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else:
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@ -412,8 +419,11 @@ class MPU:
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self.p |= (register_value - tbyte) & self.NEGATIVE
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def opSBC(self, x):
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self._opSBC(x, decimal_flags_use_adjusted_result=False)
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def _opSBC(self, x, decimal_flags_use_adjusted_result):
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if self.p & self.DECIMAL:
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self._opSBCDecimal(x)
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self._opSBCDecimal(x, decimal_flags_use_adjusted_result)
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return
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data = self.ByteAt(x())
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@ -430,47 +440,68 @@ class MPU:
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self.p |= data & self.NEGATIVE
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self.a = data
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def _opSBCDecimal(self, x):
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def _opSBCDecimal(self, x, flags_use_adjusted_result=False):
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"""SBC opcode in BCD mode.
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This is sufficiently different on 6502 and 65C02 to warrant a separate
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implementation, see e.g. http://6502.org/tutorials/decimal_mode.html#A
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See e.g. http://6502.org/tutorials/decimal_mode.html#A for details
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"""
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data = self.ByteAt(x())
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halfcarry = 1
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#
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# halfcarry = 1
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decimalcarry = 0
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adjust0 = 0
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adjust1 = 0
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# adjust0 = 0
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# adjust1 = 0
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#
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# nibble0 = (self.a & 0xf) + (~data & 0xf) + (self.p & self.CARRY)
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# if nibble0 <= 0xf:
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# halfcarry = 0
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# adjust0 = 10 # -0x6
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# nibble1 = ((self.a >> 4) & 0xf) + ((~data >> 4) & 0xf) + halfcarry
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# if nibble1 <= 0xf:
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# adjust1 = 10 << 4 # -0x60
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nibble0 = (self.a & 0xf) + (~data & 0xf) + (self.p & self.CARRY)
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if nibble0 <= 0xf:
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halfcarry = 0
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adjust0 = 10
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nibble1 = ((self.a >> 4) & 0xf) + ((~data >> 4) & 0xf) + halfcarry
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if nibble1 <= 0xf:
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adjust1 = 10 << 4
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# the ALU outputs are not decimally adjusted
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aluresult = self.a + (~data & self.byteMask) + \
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(self.p & self.CARRY)
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# the ALU outputs are not yet decimally adjusted
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aluresult = self.a + (~data & self.byteMask) + (self.p & self.CARRY)
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if aluresult > self.byteMask:
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decimalcarry = 1
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aluresult &= self.byteMask
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# but the final result will be adjusted
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nibble0 = (aluresult + adjust0) & 0xf
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nibble1 = ((aluresult + adjust1) >> 4) & 0xf
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AL = (self.a & 0xf) - (data & 0xf) + (self.p & self.CARRY) - 1
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# Update result for use in setting flags below
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adjresult = (nibble1 << 4) + nibble0
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if flags_use_adjusted_result: # Note: 65C02 but not 65816
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A = self.a - data + (self.p & self.CARRY) - 1
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assert (A & self.byteMask) == aluresult
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if A < 0:
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A -= 0x60
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if AL < 0:
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A -= 0x6
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else:
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# Note: 65816 apparently uses this logic instead of 65C02
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if AL < 0:
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AL = ((AL - 0x6) & 0xf) - 0x10
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A = (self.a & 0xf0) - (data & 0xf0) + AL
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if A < 0:
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A -= 0x60
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adjresult = A & self.byteMask
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if flags_use_adjusted_result: # 65C02 and 65816
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# Z and N use adjusted (i.e. decimal) result
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zerores = adjresult
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negativeres = adjresult
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else: # 6502
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# Z and N uses unadjusted (i.e. binary) ALU result
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zerores = aluresult
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negativeres = aluresult
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self.p &= ~(self.CARRY | self.ZERO | self.NEGATIVE | self.OVERFLOW)
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if aluresult == 0:
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if zerores == 0:
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self.p |= self.ZERO
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else:
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self.p |= aluresult & self.NEGATIVE
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self.p |= negativeres & self.NEGATIVE
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if decimalcarry == 1:
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self.p |= self.CARRY
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if ((self.a ^ data) & (self.a ^ aluresult)) & self.NEGATIVE:
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@ -66,73 +66,8 @@ class MPU(mpu6502.MPU):
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def opADC(self, x):
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return self._opADC(x, flags_use_adjusted_result=True)
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def _opSBCDecimal(self, x):
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"""SBC opcode in binary mode (non-BCD)"""
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data = self.ByteAt(x())
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decimalcarry = 0
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#adjust0 = 0
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#adjust1 = 0
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#nibble0 = (self.a & 0xf) + (~data & 0xf) + (self.p & self.CARRY)
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#if nibble0 <= 0xf:
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#halfcarry = 0
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#adjust0 = 10 # 0xa = -0x6
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#nibble1 = ((self.a >> 4) & 0xf) + ((~data >> 4) & 0xf) + halfcarry
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#if nibble1 <= 0xf:
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#adjust1 = 10 << 4 # -0x60
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# the ALU outputs are not decimally adjusted
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aluresult = self.a + (~data & self.byteMask) + \
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(self.p & self.CARRY)
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if aluresult > self.byteMask:
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decimalcarry = 1
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aluresult &= self.byteMask
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#A2 = (self.a + ~data + (self.p & self.CARRY))
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#print "A = %02X, %02X, A2 = %02X, a=%02X, data=%02X, alu=%02X" % (A, (A & self.byteMask), A2, self.a, data, aluresult)
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#assert A == A2
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# but the final result will be adjusted
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#nibble0 = (aluresult + adjust0) & 0xf
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#nibble1 = ((aluresult + adjust1) >> 4) & 0xf
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# Update result for use in setting flags below
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#adjresult = (nibble1 << 4) + nibble0
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A = self.a - data + (self.p & self.CARRY) - 1
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AL = (self.a & 0xf) - (data & 0xf) + (self.p & self.CARRY) - 1
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assert (A & self.byteMask) == aluresult
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# XXX
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if A < 0:
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#print A, A2
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#assert adjust1, (A, adjust1)
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A -= 0x60
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if AL < 0:
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#assert adjust0, (AL, adjust0)
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A -= 0x6
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#if (A & self.byteMask) != adjresult:
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# print "a=%02X data=%02X carry=%02X, res=%02X, adj=%02X" % (
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# self.a, data, self.p & self.CARRY, A & self.byteMask, adjresult)
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#assert False
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adjresult = A & self.byteMask
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self.p &= ~(self.CARRY | self.ZERO | self.NEGATIVE | self.OVERFLOW)
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if adjresult == 0:
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self.p |= self.ZERO
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else:
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self.p |= adjresult & self.NEGATIVE
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if decimalcarry == 1:
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self.p |= self.CARRY
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if ((self.a ^ data) & (self.a ^ aluresult)) & self.NEGATIVE:
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self.p |= self.OVERFLOW
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self.a = adjresult
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def opSBC(self, x):
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return self._opSBC(x, decimal_flags_use_adjusted_result=True)
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# instructions
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@ -67,13 +67,21 @@ class BinaryObjectTests(unittest.TestCase):
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if mpu.pc == old_pc or mpu.pc == 0x1003:
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break
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assert mpu.memory[0x0b] == 0
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if mpu.memory[0x0b] != 0:
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assert False, ("N1={:02x} N2={:02x} HA={:02x} HNVZC={:08b} DA={"
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":02x} DNVZC={:08b} AR={:02x} NF={:08b} VF={:08b} "
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"ZF={:08b} CF={:08b}".format(
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mpu.memory[0x00], mpu.memory[0x01], mpu.memory[0x02],
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mpu.memory[0x03], mpu.memory[0x04],mpu.memory[0x05], mpu.memory[0x06],
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mpu.memory[0x07],mpu.memory[0x08], mpu.memory[0x09],
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mpu.memory[0x0a]
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))
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class Functional6502Tests(BinaryObjectTests):
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def test6502DecimalTest(self):
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self._decimalTest("devices/bcd/6502_decimal_test.bin")
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def Xtest6502DecimalTest(self):
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self.decimalTest("devices/bcd/6502_decimal_test.bin")
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def _get_target_class(self):
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return py65.devices.mpu6502.MPU
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@ -82,7 +90,7 @@ class Functional6502Tests(BinaryObjectTests):
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class Functional65C02Tests(BinaryObjectTests):
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def test65C02DecimalTest(self):
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self._decimalTest("devices/bcd/65C02_decimal_test.bin")
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self.decimalTest("devices/bcd/65C02_decimal_test.bin")
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def _get_target_class(self):
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return py65.devices.mpu65c02.MPU
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