No problem.
I think I can better help you if you outlined the spec for the 64-bit field
and told me what exactly you wanted to do with it, but I'll try to help based
on what you've told me so far...
Currently, masking a uint64 does not work (at least I couldn't do it
on my machine).
You can only mask an int up to 32 bits. So, you would have to define
two 32-bit fields
and adjust the masks accordingly.
For your most recent example, you can do something like:
-- 24-bit integer in upper 32 bits of 64-bit flags
fields.shred_foo = ProtoField.uint32("shred.foo", "Foo field",
base.DEC, nil, 0x00FFFFFF)
-- read-only bit at bit 1 of 64-bit flags
fields.shred_rd = ProtoField.bool("shred.rd", "Read only", base.DEC, nil, 0x02)
[...]
local OFFSET_FLAGS = offset+8
local OFFSET_FLAGS_LSB = OFFSET_FLAGS+7
subtree:add(fields.shred_foo, buf(OFFSET_FLAGS, 4))
subtree:add(fields.shred_rd, buf(OFFSET_FLAGS_LSB, 1))