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it all makes sense now...

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This commit is contained in:
Jaklyy
2024-06-09 19:10:43 -04:00
parent b90d5c2320
commit ae0824fdd3
3 changed files with 36 additions and 64 deletions
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71
src/ARM.cpp
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@ -286,47 +286,6 @@ void ARM::SetupCodeMem(u32 addr)
}
}
void ARMv5::BuggedJumpTo32(const u32 addr)
{
// ldrd to pc
// behavior seems to be related to if a bugged 8/16 bit write has prefetch aborted (does any p.abort work?)
// switching to thumb mode only seems to work the first time an ldrd pc is executed after one of the above aborts?
// also it can restore cpsr but only if the PU is disabled (?????????????????????????????????????)
if (BuggyJump == 1)
{
BuggyJump = 2;
if (CP15Control & (1<<15))
JumpTo(addr & ~0x1, !(CP15Control & 1));
else
JumpTo(addr, !(CP15Control & 1));
}
else
{
JumpTo(addr & ~0x1, !(CP15Control & 1));
}
}
void ARMv5::BuggedJumpTo(const u32 addr)
{
// 16 and 8 bit loads (signed instructions included) to pc
// if they're misaligned they'll prefetch abort
// but they can only prefetch abort once, every time afterwards will succeed (more testing needed)
// if the lsb is set they will try to switch to thumb state, though it'll fail if they haven't prefetch aborted yet
if ((BuggyJump == 0) && (addr & 0x3))
{
if (addr & 0x1) CPSR |= 0x20;
BuggyJump = 1;
PrefetchAbort();
return;
}
if (CP15Control & (1<<15))
JumpTo(addr & ~0x1);
else
JumpTo(addr);
}
void ARMv5::JumpTo(u32 addr, bool restorecpsr)
{
if (restorecpsr)
@ -395,14 +354,25 @@ void ARMv5::JumpTo(u32 addr, bool restorecpsr)
NDS.MonitorARM9Jump(addr);
}
void ARMv4::BuggedJumpTo32(const u32 addr)
void ARMv5::JumpTo8_16Bit(const u32 addr)
{
JumpTo(addr & ~1); // todo
}
void ARMv4::BuggedJumpTo(const u32 addr)
{
JumpTo(addr & ~1); // todo
// 8 and 16 loads (signed included) to pc
if (!(CP15Control & 0x1))
{
// if the pu is disabled it behaves like a normal jump
JumpTo((CP15Control & (1<<15)) ? (addr & ~0x1) : addr);
}
else
{
if (addr & 0x3)
{
// if the pu is enabled it will always prefetch abort if not word aligned
// although it will still attempt (and fail) to enter thumb mode if enabled
if ((addr & 0x1) && !(CP15Control & (1<<15))) CPSR |= 0x20;
PrefetchAbort();
}
else JumpTo(addr);
}
}
void ARMv4::JumpTo(u32 addr, bool restorecpsr)
@ -449,6 +419,11 @@ void ARMv4::JumpTo(u32 addr, bool restorecpsr)
}
}
void ARMv4::JumpTo8_16Bit(const u32 addr)
{
JumpTo(addr & ~1); // checkme?
}
void ARM::RestoreCPSR()
{
u32 oldcpsr = CPSR;