Building DynCall with generic makefiles
=======================================


Description
-----------

Makefile.generic is a simple and _hybrid_ make-based build system setup for dyncall, 
designed to work with with GNU and BSD make.

This build-flavour supports two operating modes: Embedded and Configure.

Project files are specified in Makefile.generic.


History
-------
During the integration of dyncall into the R package rdyncall, there
was a need for a clean simple build system that could be launched from R
and works with various make's such as GNU, BSD and sun make.


Generic Usage
-------------

[g|bsd]make [-f Makefile.generic] [all|clean|install|...] [INSTALL_TOP=<path>]


Embedded Mode
-------------
Makefile.generic makefiles are taken "as-is" without the need for extra configuration.

<VAR1>=<VALUE1> ... bsdmake -f Makefile.generic
<VAR1>=<VALUE1> ... gmake -f Makefile.generic

(Note that setting an env var as above (<VAR1>=<VALUE1>) before running a command is
shell specific. If your shell doesn't support this, set it according to the shell's
style.)

Example:
  dyncall libraries should compile fine on most platforms:
  
  BSDmake:
  $ bsdmake -f Makefile.generic

  GNUmake:
  $ make -f Makefile.generic

  The tests sometimes require special attention to additional 'usual' libraries
  such as math and dynamic linker run-time libs.
  $ LDFLAGS="-lm -ldl" make -f Makefile.generic


Configure Mode
--------------

Usage:

  cd <build-dir> # build-dir can be arbitrary
  ../<path-to-source>/configure [--prefix=<path>]
  make
  make install [DESTDIR=<path>]

The configure script 'configure' writes 'Makefile' files that 
include 'Makefile.generic' and setup variables such as 
VPATH, {SRC,BLD}{TOP,DIR}.

Two build types are supported: In-source and out-of-Source.

in-source builds:
Makefile's are created in parallel to the Makefile.generic files.

out-of-source builds:
the configure script is executed from a (possible empty) build directory. 
The source directory tree is duplicated into that directory.


Useful Variables
----------------

For libraries:
  CC, CFLAGS, CPPFLAGS
For tests:
  CXX, LDFLAGS

MAKE_CMD - The make tool (including -f flag) to run sub-directories.
SRCTOP   - Source top-level directory (defaults to relative top).
BLDTOP   - Build  top-level directory (defaults to SRCTOP).
SRCDIR   - Source directory (defaults to '.').
BLDDIR   - Build  directory (defaults to SRCDIR).

e.g. Makefile.generic in source-tree:

SRCTOP ?= ../../../ # relative path to source-top
BLDTOP ?= ${SRCTOP} # defaults for in-source builds
SRCDIR ?= .         # relative path to current directory
BLDDIR ?= ${BLDDIR} # relative path to current directory


Include Directories
-------------------
Use -I${SRCTOP}/... to refer to other include directories.


Link Directories
----------------
Use -L${BLDTOP}/... to refer to other build directories.


Plaform Notes:
--------------
Linux: 
- all: ok.
  make -f Makefile.generic all
- tests: need 'm' and 'dl' libs. 
  ( cd tests ; LDFLAGS="-lm -ldl" make -f Makefile.generic )
- see batch script: buildsys/scripts/batch-build-linux.sh

Minix: No dynload support. No '-fPIC' is allowed.
- dynload: unsupport, no dynamic linker present in Minix 3.
- dyn{call,callback}: ok, without '-fPIC'!
  ( cd dyncall ; CFLAGS= make -f Makefile.generic dyncall dyncallback )
- tests: ok
  ( cd test ; make -f Makefile.generic all-dyncall all-dyncallback )
- see batch script: buildsys/scripts/batch-build-minix.sh

NetBSD/FreeBSD:
- all: ok.
  make -f Makefile.generic all
- tests: need math lib:
  ( cd tests ; LDFLAGS="-lm" make -f Makefile.generic )

OpenBSD:
- all: ok.
  make -f Makefile.generic all
- tests: *.cpp implicit rule not set, therefore only c tests work:
  ( cd tests ; LDFLAGS="-lm" make -f Makefile.generic all-c )
- install: ok.

Haiku Alpha 2:
- dynload: elf.h header found, install system source for dynload support
- dyn{call,callback}: ok.
  make -f Makefile.generic dyncall dyncallback
- tests: ok
  ( cd test ; make -f Makefile.generic all-dyncall all-dyncallback )


Build notes related to dyncall:
-------------------------------

CFLAGS
  Use '-fPIC' for at least 64-bit systems and when you want the code to be 
  included as a shared library or module image.
LDFLAGS
  Use '-lm' for test/suite - it uses pow function.
  Use '-ldl' for dynload examples such as test/nm and test/resolve_self on Linux.


Feature:
--------
configure --prefix=<prefix> -> Makefile DESTDIR=variable
make -f Makefile.generic DESTDIR=<prefix>


Todo: 
-----
- sun's make: CXX does not exist.. no rule for *.cpp files but *.cc.

