dividend and divisor are supposed to be a twos compliment numbers.
Fix OV calculation. Previously, it was using power_setsoov which I think is only for add and subtract operations.
Fix CR calculation. It depends on the remainder, not the quotient.
dividend is supposed to be a twos compliment number.
Fix test for dividend = -0x80000000 and divisor = -1. Previously, the test was assuming dividend was a 32-bit value from rA.
Fix OV calculation. Previously, it was using power_setsoov which I think is only for add and subtract operations.
Fix CR calculation. It depends on the remainder, not the quotient.
For MPC601 CPUs, all values of rA return 64 though the manual says undefined values of rA produce undefined results.
For non-MPC601 CPUs, if this instruction is included (such as for risu DPPC) then return results that are obtained from a G4 running Mac OS 9.2.2.
Making a negative value positive requires unary negate operator rather than binary and operator since negative numbers are stored using twos compliment.
If ov is set then clear overflow when overflow doesn't happen.
- Rename DEC to DEC_S and add DEC_U.
- MQ, RTCL_U, RTCU_U, and DEC_U should cause an illegal instruction program exception for non-MPC601 CPUs. The exception handler of classic Mac OS uses this to emulate the instruction.
- For mtspr, the SPRs RTCL_U, RTCU_U, and DEC_U are treated as no-op on MPC601.
- For debugging, use the supervisor instead of the user SPR number as the index for storing the values for RTC, TB, and DEC.
- For debugging, RTC, TB, and DEC should be updated after each access. Previously, mfspr and mtspr would only update the half of RTC and TB that was being accessed instead of both halves.
Accessing an SPR with bit 4 set (> 15) requires supervisor privilege and should cause a supervisor-level instruction exception (privileged instruction type program exception).
The first option is a flag that enables MPC601 (POWER) instructions for CPUs that are not MPC601.
This can be useful for the following reasons:
1) To produce results similar to classic Mac OS which emulates MPC601 instructions on CPUs that don't implement MPC601 instructions. This option is used to compare the risu traces produced in Mac OS 9 on a G3 or G4 with DPPC.
2) May increase performance in apps that use POWER instructions on emulated machines with CPUs that are not MPC601. It is not known if any such apps exist but there could be since Apple included MPC601 emulation in classic Mac OS.
I don't know if the compiler is smart enough to figure out that ((guest_va & 0xFFF) + sizeof(T)) > 0x1000) is always false when sizeof(T) == 1 so we'll add a check for sizeof(T) > 1.
Last step of CMD_COMPLETE_STEPS includes INTSTAT_SO to indicate to CurioSCSIController::fsmCompleting that it returned both a status byte and a message byte in the FIFO.
- For pdm/amic, real_dma_xfer is called when SCSI_DMA_Ctrl has the run bit set.
- For tnt/grandcentral, dma_wait is called when the DBDMA is started (run bit is set). It will call real_dma_xfer when the phase and sequence are DATA_IN/RCV_DATA or DATA_OUT/SEND_DATA.
- dma_wait and real_dma_xfer uses a one shot timer instead of a loop to continue doing DMA while also giving time to the CPU. This and the above changes handles the case where the DBDMA is started before setting up the transfer phase and sequence.
- dma_stop will stop the one shot timer when the DBDMA channel is stopped.
