All versions of MicroEMACS are built from the two sets of source files. One set is independent of operating system and terminal, and the other set is dependent.

Compile time options for the independent modules are selected by setting compilation switches in def.h, and then letting conditional compilation do the right thing.

The dependent modules are briefly described below.

Operating System

MicroEMACS runs on several operating systems, including Linux, FreeBSD, and Windows. Support code for other operating systems has been lost (in the distant past, these included CP/M-86 and MS-DOS on the DEC Rainbow, VMS on the VAX, CP/M-68K, GEMDOS, and FlexOS V60/68K/286). The following modules contain code dependencies on the operating system:

• ttyio.c - low level terminal I/O; independent of terminal type.

• spawn.c - subjob creation.

• fileio.c - low level file handling.

• bcopy.s or bcopy.asm - fast byte copy and fill functions.

Adding a new operating system consists mostly of changing these files, and the header file sysdef.h.

Terminal Support

MicroEMACS supports several kinds of terminals: those supporting ncurses or termcap, and the native Windows text console (the code for real-mode PC displays and OS/2 terminal windows has been lost). The following modules contain code dependencies on the terminal type:

• tty.c - high-level terminal support.

• ttyio.c - low-level terminal support.

• ttykbd.c - keyboard dependencies and extensions.

Changing terminal type consists mostly of changing these files, and the header file ttydef.h These files are located in separate per-terminal subdirectories of the tty directory.

Some terminals have memory mapped displays, or interfaces that act as such. These include ncurses and Windows text consoles. Support for these displays is enabled by setting the MEMMAP switch in ttydef.h to 1. This eliminates the fancy Gosling screen update code in display.c, and enables writing directly to screen memory (or to a screen buffer that the terminal interface library later writes to the screen).

To support a new memory-mapped display, you must provide a putline function for writing lines to the display. On old DOS-base systems, this code was written in assembly language, but on modern terminals it is written in C and placed in tty.c.

Building with GCC

To build MicroEMACs on Linux, FreeBSD, or Windows using Cygwin or MinGW, use these commands:

mkdir obj
cd obj
../configure
make # gmake on FreeBSD

You can supply one or more optional parameters to the configure command:

--with-termcap

Use this option to make MicroEMACS use the terminfo / termcap libraries for screen management, instead of the default ncursesw library. This option will not work on Windows.

--enable-debug

Use this option to compile and build MicroEMACS with debugging information, so that it can be debugged with gdb.

--with-ruby

Use this option to build support for Ruby extensions into MicroEMACS. This option will not work on Windows or FreeBSD. See the Ruby Extensions section for more information.

--with-pcre2

Use this option to use the PCRE2 library for Perl-compatible regular expressions, instead of the default Henry Spencer (circa 1986) regular expressions.