esp.c: implement DMA Transfer Pad command for DATA phases

The Transfer Pad command is used to either drop incoming FIFO data during the
DATA IN phase or generate a series of zero bytes in the FIFO during the DATA
OUT phase.

Implement the DMA Transfer Pad command for the DATA phases which is used by
the NeXTCube firmware in the DATA IN phase to ignore part of the incoming SCSI
data as it is copied into memory.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Helge Deller <deller@gmx.de>
Tested-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20240112125420.514425-85-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
1 file changed