void cpuSetUpInterrupt(ULO new_interrupt_level)
{
UWO vector_offset = (UWO) (0x60 + new_interrupt_level*4);
ULO vector_address = memoryReadLong(cpuGetVbr() + vector_offset);
cpuActivateSSP(); // Switch to using ssp or msp. Loads a7 and preserves usp if we came from user-mode.
cpuStackFrameGenerate(vector_offset, cpuGetPC()); // This will end up on msp if master is enabled, or on the ssp/isp if not.
cpuSetSR(cpuGetSR() & 0x38ff); // Clear interrupt level
cpuSetSR(cpuGetSR() | 0x2000); // Set supervisor mode
cpuSetSR(cpuGetSR() | (UWO)(new_interrupt_level << 8)); // Set interrupt level
#ifdef CPU_INSTRUCTION_LOGGING
cpuCallInterruptLoggingFunc(new_interrupt_level, vector_address);
#endif
if (cpuGetModelMajor() >= 2 && cpuGetModelMajor() < 6)
{
if (cpuGetFlagMaster())
{ // If the cpu was in master mode, preserve msp, and switch to using ssp (isp) in a7.
ULO oldA7 = cpuGetAReg(7);
cpuSetMspDirect(oldA7);
cpuSetAReg(7, cpuGetSspDirect());
cpuFrame1(vector_offset, cpuGetPC()); // Make the throwaway frame on ssp/isp
cpuSetSR(cpuGetSR() & 0xefff); // Clear master bit
}
}
cpuInitializeFromNewPC(vector_address);
cpuSetStop(FALSE);
cpuSetRaiseInterrupt(FALSE);
}
/// <summary>
/// Returns the interrupt stack pointer. ssp is used as isp.
/// </summary>
ULO cpuGetIspAutoMap(void)
{
if (cpuGetFlagSupervisor() && !cpuGetFlagMaster())
{
return cpuGetAReg(7);
}
return cpuGetSspDirect();
}
ULO cpuActivateSSP(void)
{
ULO currentSP = cpuGetAReg(7);
// check supervisor bit number (bit 13) within the system byte of the status register
if (!cpuGetFlagSupervisor())
{
// we are in user mode, thus save user stack pointer (USP)
cpuSetUspDirect(currentSP);
currentSP = cpuGetSspDirect();
if (cpuGetModelMajor() >= 2)
{
if (cpuGetFlagMaster())
{
currentSP = cpuGetMspDirect();
}
}
cpuSetAReg(7, currentSP);
}
return currentSP;
}
ULO cpuGetSspAutoMap(void) {return (cpuGetFlagSupervisor()) ? cpuGetAReg(7) : cpuGetSspDirect();}
