Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mit-eddie!apollo!oj
From: oj@apollo.COM (Ellis Oliver Jones)
Newsgroups: comp.sys.apollo
Subject: Re: GPR Colour Maps
Message-ID: <4442004a.d5b2@apollo.COM>
Date: 6 Jul 89 13:11:00 GMT
References: <8907051320.AA03260@umix.cc.umich.edu>
Reply-To: oj@apollo.com  (Ollie Jones)
Organization: Apollo Computer, Chelmsford, MA
Lines: 22

In article <8907051320.AA03260@umix.cc.umich.edu> FERGUSON@TMASL.EXXON.COM writes:
>
>     I know that changing a color map requires that the display is
>     acquired. Otherwise, you'll get a status error back.
True, but this is not a problem in borrow mode.
>
>     The arguments for gpr_$set_color_map(start,num_entries,map,status);
>     are kind of funny. The 'start' is a long (or 4-byte) integer, the
>     'num_entries' is a short (16-bit) integer, the 'map' is an array
>     of long integers, and status is finally a status_$t, or 4-bytes.
Yes.  If you're using C and SR10 or later, you can have an easier time
with this by using /usr/apollo/include/gpr.h instead of /sys/ins/gpr.ins.c .
The .h files have function prototypes (hooray) and allow the compiler
to get the data types right, or at least error-check them.
>
>     ... two-byte integers were used whenever possible to save
>     time (this is my theory, not gospel).
I wouldn't sanctify this business by referring to our dirty laundry
as "gospel."  :-)  Your theory is correct, though.  Two-byte integers
also save some address space.

/Ollie Jones (speaking for myself, not necessarily for HP)