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Bankswitching for ROM banks now working OK. 

git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@2911 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba
This commit is contained in:
adavie 2014-06-06 23:29:00 +00:00
parent 68c3c42254
commit d0092580e0
2 changed files with 6 additions and 14 deletions
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18
src/emucore/CartDASH.cxx
View File

@ -65,7 +65,7 @@ void CartridgeDASH::reset() {
// We'll map the startup bank (0) from the image into the third 1K bank upon reset
bank(myStartBank);
bankROM(myStartBank);
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@ -90,18 +90,12 @@ void CartridgeDASH::install(System& system) {
// Setup the last segment (of 4, each 1K) to point to the first ROM slice
// Actually we DO NOT want "always". It's just on bootup, and can be out switched later
access.type = System::PA_READ;
for (uInt32 address = (0x2000 - ROM_BANK_SIZE); address < 0x2000; address += (1 << shift)) {
access.directPeekBase = &myImage[address & (ROM_BANK_SIZE - 1)]; // from base address 0x0000 in image
access.codeAccessBase = &myCodeAccessBase[address & (ROM_BANK_SIZE - 1)];
mySystem->setPageAccess(address >> shift, access);
// TODO: In this and other implementations we appear to be using "shift" as a system-dependant mangle for
// different access types (byte/int/32bit) on different architectures. I think I understand that much. However,
// I have an issue with how these loops are encoded in all the bank schemes I've seen. The issue being that
// the loop inits set some address (e.g., 0x1800) and then add a shifted value to it every loop. But when
// they want to get the downshifted value, they just shift down the whole value. Which will also shift down that base address
// and that makes no sense at all to me. I don't understand it.
}
// Initialise bank values for the 4x 1K bank areas
@ -182,7 +176,6 @@ bool CartridgeDASH::bankRAM(uInt8 bank) {
bankInUse[bankNumber] = (Int16) (BITMASK_ROMRAM | currentBank); // Record which bank switched in (marked as RAM)
bankInUse[bankNumber + 4] = (Int16) (BITMASK_ROMRAM | currentBank); // Record which (write) bank switched in (marked as RAM)
// Setup the page access methods for the current bank
System::PageAccess access(0, 0, 0, this, System::PA_READ);
@ -218,21 +211,22 @@ bool CartridgeDASH::bankROM(uInt8 bank) {
uInt16 shift = mySystem->pageShift();
uInt16 bankNumber = ((bank >> BANK_BITS) & 3) << 1; // which bank # we are switching TO (BITS D6,D7)
uInt16 bankNumber = (bank >> BANK_BITS) & 3; // which bank # we are switching TO (BITS D6,D7)
uInt16 currentBank = bank & BIT_BANK_MASK; // Wrap around/restrict to valid range
// Map ROM bank image into the system into the correct slot
// Memory map is 1K slots at 0x1000, 0x1400, 0x1800, 0x1C00
// Each ROM uses 2 consecutive 512 byte slots
bankInUse[bankNumber] = bankInUse[bankNumber + 1] = (Int16) currentBank; // Record which bank switched in (as ROM)
bankInUse[bankNumber * 2] = bankInUse[bankNumber * 2 + 1] = (Int16) currentBank; // Record which bank switched in (as ROM)
uInt32 startCurrentBank = currentBank << ROM_BANK_TO_POWER; // Effectively *1K
// Setup the page access methods for the current bank
System::PageAccess access(0, 0, 0, this, System::PA_READ);
for (uInt32 address = 0x1000; address < 0x1000 + ROM_BANK_SIZE; address += (1 << shift)) {
uInt32 base = 0x1000 + (bankNumber << ROM_BANK_TO_POWER);
for (uInt32 address = base; address < base + ROM_BANK_SIZE; address += (1 << shift)) {
access.directPeekBase = &myImage[startCurrentBank + (address & (ROM_BANK_SIZE - 1))];
access.codeAccessBase = &myCodeAccessBase[startCurrentBank + (address & (ROM_BANK_SIZE - 1))];
mySystem->setPageAccess(address >> shift, access);

2
src/emucore/CartDASH.hxx
View File

@ -283,8 +283,6 @@ private:
static const Int16 BANK_UNDEFINED = -1; // bank is undefined and inaccessible
uInt16 myCurrentBank;
uInt8 myRAM[RAM_TOTAL_SIZE];
};