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Refactor code and comments for TIA and RIOT 'page access' stuff.

This commit is contained in:
Stephen Anthony 2017-09-15 21:22:10 -02:30
parent 5f68b0565d
commit ca69e2ed73
2 changed files with 23 additions and 18 deletions
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31
src/emucore/M6532.cxx
View File

@ -150,10 +150,15 @@ void M6532::installDelegate(System& system, Device& device)
// All accesses are to the given device
System::PageAccess access(&device, System::PA_READWRITE);
// We're installing in a 2600 system
for(int address = 0; address < 8192; address += (1 << System::PAGE_SHIFT))
if((address & 0x1080) == 0x0080)
mySystem->setPageAccess(address >> System::PAGE_SHIFT, access);
// Map all peek/poke to mirrors of RIOT address space to this class
// That is, all mirrors of ZP RAM ($80 - $FF) and IO ($280 - $29F) in the
// lower 4K of the 2600 address space are mapped here
// The two types of addresses are differentiated in peek/poke as follows:
// (addr & 0x0200) == 0x0000 is ZP RAM (A9 is 0)
// (addr & 0x0200) != 0x0000 is IO (A9 is 1)
for(uInt16 addr = 0; addr < 0x1000; addr += (1 << System::PAGE_SHIFT))
if((addr & 0x0080) == 0x0080)
mySystem->setPageAccess(addr >> System::PAGE_SHIFT, access);
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@ -161,11 +166,10 @@ uInt8 M6532::peek(uInt16 addr)
{
updateEmulation();
// Access RAM directly. Originally, accesses to RAM could bypass
// this method and its pages could be installed directly into the
// system. However, certain cartridges (notably 4A50) can mirror
// the RAM address space, making it necessary to chain accesses.
if((addr & 0x1080) == 0x0080 && (addr & 0x0200) == 0x0000)
// A9 distinguishes I/O registers from ZP RAM
// A9 = 1 is read from I/O
// A9 = 0 is read from RAM
if((addr & 0x0200) == 0x0000)
return myRAM[addr & 0x007f];
switch(addr & 0x07)
@ -230,11 +234,10 @@ bool M6532::poke(uInt16 addr, uInt8 value)
{
updateEmulation();
// Access RAM directly. Originally, accesses to RAM could bypass
// this method and its pages could be installed directly into the
// system. However, certain cartridges (notably 4A50) can mirror
// the RAM address space, making it necessary to chain accesses.
if((addr & 0x1080) == 0x0080 && (addr & 0x0200) == 0x0000)
// A9 distinguishes I/O registers from ZP RAM
// A9 = 1 is write to I/O
// A9 = 0 is write to RAM
if((addr & 0x0200) == 0x0000)
{
myRAM[addr & 0x007f] = value;
return true;

10
src/emucore/tia/TIA.cxx
View File

@ -177,10 +177,12 @@ void TIA::installDelegate(System& system, Device& device)
// All accesses are to the given device
System::PageAccess access(&device, System::PA_READWRITE);
// We're installing in a 2600 system
for(uInt32 i = 0; i < 8192; i += (1 << System::PAGE_SHIFT))
if((i & 0x1080) == 0x0000)
mySystem->setPageAccess(i >> System::PAGE_SHIFT, access);
// Map all peek/poke to mirrors of TIA address space to this class
// That is, all mirrors of ($00 - $3F) in the lower 4K of the 2600
// address space are mapped here
for(uInt16 addr = 0; addr < 0x1000; addr += (1 << System::PAGE_SHIFT))
if((addr & 0x0080) == 0x0000)
mySystem->setPageAccess(addr >> System::PAGE_SHIFT, access);
mySystem->m6502().setOnHaltCallback(
[this] () {