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fix #663 (illegal segment access)

This commit is contained in:
thrust26 2020-06-12 12:48:15 +02:00
parent dc3324e083
commit 9cf4686bc2
2 changed files with 35 additions and 8 deletions
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26
src/emucore/CartEnhanced.cxx
View File

@ -155,8 +155,7 @@ uInt8 CartridgeEnhanced::peek(uInt16 address)
// This is a read access to a write port! // This is a read access to a write port!
// Reading from the write port triggers an unwanted write // Reading from the write port triggers an unwanted write
// The RAM banks follow the ROM banks and are half the size of a ROM bank // The RAM banks follow the ROM banks and are half the size of a ROM bank
return peekRAM(myRAM[((myCurrentSegOffset[(peekAddress & ROM_MASK) >> myBankShift] - mySize) >> 1) + address], return peekRAM(myRAM[ramAddressSegmentOffset(peekAddress) + address], peekAddress);
peekAddress);
} }
address &= ROM_MASK; address &= ROM_MASK;
@ -168,8 +167,7 @@ uInt8 CartridgeEnhanced::peek(uInt16 address)
return peekRAM(myRAM[address], peekAddress); return peekRAM(myRAM[address], peekAddress);
} }
return myImage[myCurrentSegOffset[(peekAddress & ROM_MASK) >> myBankShift] return myImage[romAddressSegmentOffset(peekAddress) + (peekAddress & myBankMask)];
+ (peekAddress & myBankMask)];
} }
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@ -190,7 +188,7 @@ bool CartridgeEnhanced::poke(uInt16 address, uInt8 value)
{ {
address &= myRamMask; address &= myRamMask;
// The RAM banks follow the ROM banks and are half the size of a ROM bank // The RAM banks follow the ROM banks and are half the size of a ROM bank
pokeRAM(myRAM[((myCurrentSegOffset[(pokeAddress & ROM_MASK) >> myBankShift] - mySize) >> 1) + address], pokeRAM(myRAM[ramAddressSegmentOffset(pokeAddress) + address],
pokeAddress, value); pokeAddress, value);
return true; return true;
} }
@ -300,10 +298,22 @@ bool CartridgeEnhanced::bank(uInt16 bank, uInt16 segment)
return myBankChanged = true; return myBankChanged = true;
} }
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
uInt16 CartridgeEnhanced::romAddressSegmentOffset(uInt16 address) const
{
return myCurrentSegOffset[((address & ROM_MASK) >> myBankShift) % myBankSegs];
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
uInt16 CartridgeEnhanced::ramAddressSegmentOffset(uInt16 address) const
{
return uInt16(myCurrentSegOffset[((address & ROM_MASK) >> myBankShift) % myBankSegs] - mySize) >> 1;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
uInt16 CartridgeEnhanced::getBank(uInt16 address) const uInt16 CartridgeEnhanced::getBank(uInt16 address) const
{ {
return myCurrentSegOffset[(address & ROM_MASK) >> myBankShift] >> myBankShift; return romAddressSegmentOffset(address) >> myBankShift;
} }
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@ -335,7 +345,7 @@ bool CartridgeEnhanced::patch(uInt16 address, uInt8 value)
{ {
if(isRamBank(address)) if(isRamBank(address))
{ {
myRAM[((myCurrentSegOffset[(address & ROM_MASK) >> myBankShift] - mySize) >> 1) + (address & myRamMask)] = value; myRAM[ramAddressSegmentOffset(address) + (address & myRamMask)] = value;
} }
else else
{ {
@ -347,7 +357,7 @@ bool CartridgeEnhanced::patch(uInt16 address, uInt8 value)
myRAM[address & myRamMask] = value; myRAM[address & myRamMask] = value;
} }
else else
myImage[myCurrentSegOffset[(address & ROM_MASK) >> myBankShift] + (address & myBankMask)] = value; myImage[romAddressSegmentOffset(address) + (address & myBankMask)] = value;
} }
return myBankChanged = true; return myBankChanged = true;

17
src/emucore/CartEnhanced.hxx
View File

@ -256,6 +256,7 @@ class CartridgeEnhanced : public Cartridge
@param address The address to check @param address The address to check
@param value The optional value used to determine the bank switched to @param value The optional value used to determine the bank switched to
@return True if a bank switch happened. @return True if a bank switch happened.
*/ */
virtual bool checkSwitchBank(uInt16 address, uInt8 value = 0) = 0; virtual bool checkSwitchBank(uInt16 address, uInt8 value = 0) = 0;
@ -268,6 +269,22 @@ class CartridgeEnhanced : public Cartridge
*/ */
virtual uInt16 getStartBank() const { return 0; } virtual uInt16 getStartBank() const { return 0; }
/**
Get the ROM offset of the segment of the given address
@param address The address to get the offset for
@return The calculated offset
*/
uInt16 romAddressSegmentOffset(uInt16 address) const;
/**
Get the RAM offset of the segment of the given address
@param address The address to get the offset for
@return The calculated offset
*/
uInt16 ramAddressSegmentOffset(uInt16 address) const;
private: private:
// Following constructors and assignment operators not supported // Following constructors and assignment operators not supported
CartridgeEnhanced() = delete; CartridgeEnhanced() = delete;