Add another level of alignment because SEQ_SUB is inside SEQ_GEQ. Like this:

SEQ_GEQ
    SEQ_SUB

I am in favor of keeping this pair of "{}".

I'll indent it by a single additional space only, to be visually different from the statment in the if-clause. I have another change with a deep logcial stack of AND/ORed checks, which would end up way too far to the right if a half-tab (4 spaces) were used per bracket-level.

Just observation: this isn't a stylistic change. However it seems safe since both predicates of OR dereference tp.

Indeed; on closer examination, I should do a "sbavail() > SEQ_SUB(,), as the former is a uint, and the latter a int, which can not become larger than 2^30-2^14.