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LC: Support write-enabling LC via single 'INC abs' and similar RMW opcodes (#700)

This commit is contained in:
tomcw 2019-10-08 22:12:35 +01:00
parent 7265dee506
commit 9994635e13
2 changed files with 31 additions and 0 deletions
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30
source/LanguageCard.cpp
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@ -29,6 +29,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#include "StdAfx.h"
#include "Applewin.h"
#include "CPU.h" // GH#700
#include "LanguageCard.h"
#include "Log.h"
#include "Memory.h"
@ -74,6 +75,10 @@ BYTE __stdcall LanguageCardUnit::IO(WORD PC, WORD uAddr, BYTE bWrite, BYTE uValu
{
memmode |= MF_WRITERAM; // UTAIIe:5-23
}
else if (bWrite && pLC->GetLastRamWrite() && pLC->IsOpcodeRMWabs(uAddr)) // GH#700
{
memmode |= MF_WRITERAM;
}
}
else
{
@ -98,6 +103,31 @@ BYTE __stdcall LanguageCardUnit::IO(WORD PC, WORD uAddr, BYTE bWrite, BYTE uValu
return bWrite ? 0 : MemReadFloatingBus(nExecutedCycles);
}
// GH#700: INC $C083/C08B (RMW) to write enable the LC
bool LanguageCardUnit::IsOpcodeRMWabs(WORD addr)
{
BYTE param1 = mem[(regs.pc - 2) & 0xffff];
BYTE param2 = mem[(regs.pc - 1) & 0xffff];
if (param1 != (addr & 0xff) || param2 != 0xC0)
return false;
BYTE opcode = mem[(regs.pc - 3) & 0xffff];
if (opcode == 0xEE || // INC abs
opcode == 0xCE || // DEC abs
opcode == 0x6E || // ROR abs
opcode == 0x4E || // LSR abs
opcode == 0x2E || // ROL abs
opcode == 0x0E) // ASL abs
return true;
if ((GetMainCpu() == CPU_65C02) && (
opcode == 0x1C || // TRB abs
opcode == 0x0C)) // TSB abs
return true;
return false;
}
//-------------------------------------
LanguageCardSlot0::LanguageCardSlot0(void)

1
source/LanguageCard.h
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@ -19,6 +19,7 @@ public:
BOOL GetLastRamWrite(void) { return m_uLastRamWrite; }
void SetLastRamWrite(BOOL count) { m_uLastRamWrite = count; }
SS_CARDTYPE GetMemoryType(void) { return m_type; }
bool IsOpcodeRMWabs(WORD addr);
static BYTE __stdcall IO(WORD PC, WORD uAddr, BYTE bWrite, BYTE uValue, ULONG nExecutedCycles);