Cleanup of SCSI phase change code, and adjustment of bus settle delays.

[mactcp]

This is code cleanup around SCSI phase changes, and a couple of delays added to meet the 400ns bus settle delays in the SCSI specifications. Timing was measured on an oscilloscope.

I'm not seeing any performance impact, positive or negative, which is expected. I measured the time to receive a 10 byte command from an LC III+ at around 160us. I think that is mostly the BlueSCSI waiting on the Mac, so adding small delays didn't seem to make any difference to performance.

Tested on an LC III+ and a Quadra 650.

One thing I will note, I removed this line of code in messaging out handling:
memset(m_msb, 0x00, sizeof(m_msb));
Clearing the whole 2K buffer like that seemed unnecessary, and takes about 4us. That definitely stood out on the scope, but only impacts initiators that have a message out phase (Quadra and faster Macs).

[erichelgeson]

Hey @mactcp - thanks again, been busy but I'm planning to review & test this tomorrow.

[erichelgeson]

Worked well in my testing, looks good!