Offset Size Meaning
32 1 byte FIQ status bit mask
36 3 bytes FIQ status bit offset
48 1 byte IRQ status bit mask
52 3 bytes IRQ status bit offset
The offsets are in the cards identity space, which is only 8 bits wide for the first 16 bytes (i.e. only low byte is used for the first 16 words).
Status offsets are signed 24 bit numbers, offset from the base of podules in the memory map - with the access cycle speed encoded in bits 19-20. Bits 14-15 (slot number) should be zero. A negative offset means that the status register is in module space.
The bit mask should have only a single bit set.
If you have to have interrupt status pointers because of a chunk directory but do not wish to relocate the status bits from the default location (low byte of the ECId) you would set both offset fields to point to the low byte, with masks of 4 and 1 for FIQ and IRQ respectively.
[sh-index] Back to list of manuals
|
| |
