GNU make is required, and all of the examples herein assume that GNU make is
being used.  If your native make is not GNU, substitute gmake for make.

A C99 compiler is required to build Bocfel; or at least a compiler that supports
the C99 features that are used.  These include, but are probably not limited to,
VLAs, snprintf(), mixed declarations and code, fixed-width integers, and
compound literals.

Officially supported compilers are handled in compiler.mk.  If you get Bocfel
working with another compiler, I would be happy to add it to compiler.mk.  Note
that Bocfel has a few requirements (beyond C99) from its compilers.  Compilers
are expected to support the following rather standard Unix command-line
arguments, and are expected to work as linkers, as well:
-D - define a macro
-L - define a library search path
-l - specify a library to link
-o - specify the output file name
-g - build with debugging symbols
-c - compile but don't link, producing a .o file from a .c file
-O - Optimize (but this can be changed via the $OPT variable)

Compilers are also expected to understand optimization flags while they are
linking; modern compilers can do link-time optimization, and generally require
the same flags when compiling and linking (the system linker is usually not
smart enough to handle the link-time optimized object files).

The character set used is required to be compatible with ASCII.  This is not a
particularly onerous requirement; but if I ever have access to a system that
supports a wildly different character set, I would be willing to think about
extending support beyond ASCII.  For now, though, it is much easier to assume
ASCII, because almost everybody uses a character set that is compatible with it,
including the Z-machine.

A 32-bit system is probably a requirement.  I have tried to avoid the assumption
that "int" is 32 bits, and it is entirely possible that I have succeeded and a
system with 16-bit ints would work properly.  However, there are some lookup
tables that are 65K each, which would probably cause fits for 16-bit systems.
As with the ASCII requirement, if I ever happen upon a 16-bit system with a C99
compiler, I will probably try to get Bocfel working with it. 

I make use of fixed-width types such as uint8_t and uint16_t.  As a practical
side-effect, Bocfel requires a system with 8-, 16-, and 32-bit 2's complement
integers.  This is likely not a problem.

-------------------------------------------------------------------------------

There are two main types of build: Glk and non-Glk.  Glk builds use libraries
based on Andrew Plotkin's Glk standard for I/O.  Glk builds can be full-
featured, including timed input and cursor control, allowing games like Border
Zone and Seastalker to run as intended.  Non-Glk builds use nothing but standard
C functions.  This has the advantage of running on systems where Glk has not
been ported, but the disadvantage of missing important features.  Non-Glk builds
are generally not useful.

The first thing to do is edit config.mk and set $PLATFORM to the proper value.
See the comments in that file for an explanation.  There are other variables
that may be set through config.mk, each of which has comments explaining its
use.

To build a non-Glk interpreter, simply run:
make GLK=

The $GLK variable may also be set through config.mk.

Glk builds are slightly more involved.  For most Glk libraries (e.g. glkterm(w),
xglk, cheapglk, Windows Glk), you will want to unpack the source distribution
into the current directory (the one containing Bocfel's source), and then build
it.  After this is done, simply run
make GLK=glktermw

to build a Glk-enabled interpreter (where glktermw is the name of the directory
into which the Glk library was unpacked).  Note that the Windows Glk
distribution does not unpack into its own directory, so you will want to change
into the winglk directory before unpacking it.

The presence of a file called Make.<glk_library_name> in the Glk library
directory is required.  Most Glk libraries will include this, but at least
Windows Glk does not.  I have included a Make.winglk that should be sufficient
to build a Windows Glk-enabled interpreter, at least with MinGW.

Bocfel can also be built against Gargoyle's Glk implementation, taking full
advantage of extra features it provides.  Ben Cressey, Gargoyle's maintainer,
has imported Bocfel into the Gargoyle source repository, so the easiest way to
obtain Gargoyle support is to check out the latest version of Gargoyle's source
code; see http://code.google.com/p/garglk/source/checkout.  If you would prefer
to use Bocfel's build system to build against Gargoyle as you would any other
Glk library, read on.

The build process for Gargoyle is slightly more involved.  Gargoyle includes a
full-featured Glk library, but it is not designed for external use.  However,
getting a Gargoyle- (or rather, a garglk-) enabled build is not too difficult.

The first step is to get and install the Jam build tool from
http://www.perforce.com/jam/jam.html.  Your vendor may provide a jam package or
port; consult its documentation.

Next, get a copy of the Gargoyle source code from http://garglk.googlecode.com/.
Extract it somewhere (it need not be in the current directory).  Enter the
directory and run jam.  From the build/<youros>.release/garglk directory, copy
the files libgarglk.so and libgarglkmain.a to the directory "gargoyle" (which
contains a Make.gargoyle file) in the Bocfel source distribution.  Then copy the
files garglk/glk.h, garglk/glkstart.h, and garglk/gi_blorb.h from Gargoyle to
Bocfel's gargoyle directory.  You can now build a garglk-enabled interpreter:
make GLK=gargoyle

If you do not already have Gargoyle installed, you will need to install the
library libgarglk.so somewhere in your library search path.  I would, however,
recommend just installing Gargoyle.  If you do this, you will want to build the
source code of the same version that you install.  If you don't, it's possible
(although unlikely) that ABI or API changes in Gargoyle will cause problems.

Bocfel is built and tested against the development version of Gargoyle, so
ideally this would be the version to build against.  However, Gargoyle does, by
and large, implement a standard API, so the version should not make a large
difference.  There are a few Gargoyle-specific extensions that can possibly
change, but they have been stable apart from one change over the past couple of
years.  The current (2010.1) release of Gargoyle should work, but the only
officially supported version is whatever was current as of this version of
Bocfel's release.

-------------------------------------------------------------------------------

Glk is very portable, and there is very little system-specific code that is
needed.  However, there is a small amount.  Some libraries are, conventionally,
considered to be Unix (cheapglk, xglk, and glkterm(w)); one Windows (Windows
Glk, naturally).  Bocfel needs to know what kind of platform it is running on in
order to provide a few system-specific functions, and it uses this information
to decide what kind of Glk library is in use.  While it is theoretically
possible (for example) for a Unix-based Glk library to use a non Unix-style Glk
startup, I have no desire to require users to set both their OS and Glk
platforms.  Thus a Windows user who desires to use cheapglk (assuming it builds
on Windows) is out of luck, for example.  I consider this to be acceptable
because I expect garglk to be the preferred Glk implementation, and even if it's
not, most Glk uses will work.  When building with garglk, Unix-style Glk startup
is forced, because this is what garglk uses, regardless of platform.
