---------------------------------------------------------------------------
Anonymous FTP server:	cher.media.mit.edu (18.85.0.47)
This file:		pub/projects/interactive-c/as11/as11_ic.README
Last updated:		October 7, 1995
Maintained by:          Randy Sargent (rsargent@media.mit.edu)
---------------------------------------------------------------------------

Information about as11_ic and as11_cpp:

as11_cpp is required to assemble the file pcode.asm.

as11_ic is required to assemble objects that IC can dynamically link
in (".icb" files)

As of today, as11_ic and as11_cpp exist under UNIX and MS-DOS.  They are
currently implemented as shell scripts, and make use of a C preprocessor.

The unix versions of as11_icb and as11_cpp can be found in the as11
sources.  

The MS-DOS versions of as11_ic and as11_cpp are in
pub/projects/interactive-c/ms-dos/pcode_pc.zip (big thanks to Kent
Farnsworth!)

More information about how as11_cpp and as11_ic work:

as11_cpp is a shell script which calls a somewhat modified version of
motorola's freeware assembler, as11.  It doesn't work on all machines,
so you might need to frob with it a bit.  If worse comes to worse, you
can try running the preprocessor on the files and manually take out
all the '#' lines the preprocessor spits out, so you'll be compatible
with the unmodified as11.  It is possible on a IBM PC to manually do
this as well.

as11_ic is a shell script which simply assembles the input file at two
different locations.

pass 1: ZERO_PAGE_START=$10 MAIN_START=$8020
pass 2: ZERO_PAGE_START=$13 MAIN_START=$872B

It just calls as11_cpp twice, with different defines each time:

as11_cpp $argv -DZERO_PAGE_START=\$10 -DMAIN_START=\$8020
as11_cpp $argv -DZERO_PAGE_START=\$13 -DMAIN_START=\$872B - cre >/tmp/$$.cre

It runs the assembler the second time with the "cre" flags to create
the symbol listing at the end.

The output of as11_icb, a .icb file, is simply the two .s19 outputs
concatenated, with symbols of the second at the end.  When IC loads
this file, it compares the two different .s19 parts of the .icb to
determine how to relocate the .icb binary -arbitrarily- in memory.
OK, this is gross, but it beat hacking motorola's assembler to output
relocation information, which was my first attempt.  IC allocates some
space in zero page and some space in the upper 32K on the fly, and
puts parts of the .icb file in each.  IC then looks at the symbol
table, and records symbols starting with procedure_ or variable_ (I
don't remember if those are the exact prefixes) and sticks them in the
C symbol table.

Note that some c preprocessors are incompatible with some assembly
constructs, such as:

 #'f 

for which they will give "Unterminated character constant" or a
similar message.  If you have access to gcc, use "gcc -E -traditional"
and it should work fine.

Good luck!

Randy Sargent  rsargent@media.mit.edu
October 7, 1995