var/adm/acct and acct.h comp_t type?

[George A. Planansky]

We need to do accounting by "project" and intend to do that by having
users assume appropriate group id's, such that each project is represented
by a unique gid.  So I need to recover that gid value from the
/var/adm/acct file, and since "sa" does not give the gid value, I have to
go in and get it and the other values that accton records in that file.  

Accton builds the acct file using a structure given in the <sys/acct.h>
file.  One of the types in this structure is a comp_t type, a 16-bit
representation of some sort of "floating-point" number, with a 3-bit octal
base 8 exponent and a 13 bit fraction.  

Questions:

1. how is that comp_t type number built?  Is there a conversion function
for it in one of the libraries?  Where is it described?  Or, where is
accton better described, or its source?

2. in what units (seconds/60 ?) are the times reckoned?

3. in what units are the memory use and disk access reckoned?

4. more generally, what is out there, to do accounting beyond "sa" and
"ac".  Rather than re-invent the roller, I'd be obliged to know about some
wheels.

I can receive email as:  gplan at ra.umb.edu.
Otherwise I am George Planansky, at:  Atmosphere Environment Research, 
840 Memorial Drive, Cambridge, MA 02138 USA;  phone (617) 547-6207.