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1998-08-11 Dave Love <d.love@dl.ac.uk> * README: Update from Craig. From-SVN: r21672
110 lines
5.4 KiB
Plaintext
110 lines
5.4 KiB
Plaintext
1998-08-11
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This directory contains the libf2c library packaged for use with g77
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to configure and build automatically (in principle!) as part of the
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top-level configure and make steps. g77 names this library `libg2c'
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to avoid conflicts with existing copies of `libf2c' on a system.
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Some small changes have been made vis-a-vis the netlib distribution of
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libf2c, which comes from <ftp:bell-labs.com/netlib/f2c/> and is maintained
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(excellently) by David M. Gay <dmg@bell-labs.com>. See the Notice files
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for copyright information. We usually try to get g77-specific changes
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rolled back into the libf2c distribution.
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Files that come directly from netlib are either maintained in the
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libf2c directory under their original names or, if they are not pertinent
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for g77's version of libf2c, under their original names with `.netlib'
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appended. For example, permissions.netlib is a copy of f2c's top-level
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`permissions' file in the netlib distribution. In this case, it applies
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only to the relevant portions of the libF77/ and libI77/ directories; it
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does not apply to the libU77/ directory, which is distributed under
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different licensing arrangements. Similarly, the `makefile.netlib' files
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in the libF77/ and libI77/ subdirectories are copies of the respective
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`makefile' files in the netlib distribution, but are not used when
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building g77's version of libf2c.
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The README.netlib files in libF77/ and libI77/ thus might be
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interesting, but should not be taken as guidelines for how to
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configure and build libf2c in g77's distribution.
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* Read permissions.netlib for licensing conditions that apply to
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distributing programs containing portions of code in the libF77/ and
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libI77/ subdirectories. Also read disclaimer.netlib.
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* Read libU77/COPYING.LIB for licensing conditions that apply to
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distributing programs containing portions of code in the libU77/
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subdirectory.
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Among the user-visible changes (choices) g77 makes in its version of libf2c:
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- f2c.h configured to default to padding unformatted direct reads
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(#define Pad_UDread), because that's the behavior most users
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expect.
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- f2c.h configured to default to outputting leading zeros before
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decimal points in formatted and list-directed output, to be compatible
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with many other compilers (#define WANT_LEAD_0). Either way is
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standard-conforming, however, and you should try to avoid writing
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code that assumes one format or another.
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- dtime_() and etime_() are from Dave Love's libU77, not from
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netlib's libF77.
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- Routines that are intended to be called directly via user code
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(as in `CALL EXIT', but not the support routines for `OPEN')
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have been renamed from `<name>' to `G77_<name>_0'. This, in
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combination with g77 recognizing these names as intrinsics and
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calling them directly by those names, reduces the likelihood of
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interface mismatches occurring due to use of compiler options
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that change code generation, and permits use of these names as
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both intrinsics and user-supplied routines in applications (as
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required by the Fortran standards). f2cext.c contains "jacket"
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routines named `<name>' that call `G77_<name>_0', to support
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code that relies on calling the relevant routines as `EXTERNAL'
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routines.
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Note that the `_0' in the name denotes version 0 of the *interface*,
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not the *implementation*, of a routine. The interface of a
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given routine *must not change* -- instead, introduce a new copy
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of the code, with an increment (e.g. `_1') suffix, having the
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new interface. Whether the previous interface is maintained is
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not as important as ensuring the routine implementing the new
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interface is never successfully linked to a call in existing,
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e.g. previously compiled, code that expects the old interface.
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- Version.c in the subdirectories contains g77-specific version
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information and a routine (per subdirectory) to print both the
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netlib and g77 version information when called. The `g77 -v'
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command is designed to trigger this, by compiling, linking, and
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running a small program that calls the routines in sequence.
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- libF77/main.c no longer contains the actual code to copy the
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argc and argv values into globals or to set up the signal-handling
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environment. These have been removed to libF77/setarg.c and
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libF77/setsig.c, respectively. libF77/main.c contains procedure
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calls to the new code in place of the code itself. This should
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simplify linking executables with a main() function other than
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that in libF77/main.c (such as one written by the user in C or
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C++). See the g77 documentation for more information.
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- Complex-arithmetic support routines in libF77/ take a different approach
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to avoiding problems resulting from aliased input and output arguments,
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which should avoid particularly unusual alias problems that netlib
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libf2c might suffer from.
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- libF77/signal_.c supports systems with 64-bit pointers and 32-bit
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integers.
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- I/O routines in libI77/ have code to detect attempts to do recursive
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I/O more "directly", mainly to lead to a clearer diagnostic than
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typically occurs under such conditions.
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- Formatted-I/O routines in libI77/ have code to pretty-print a FORMAT
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string when printing a fatal diagnostic involving formatted I/O.
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- libI77/open.c supports a more robust, perhaps more secure, method
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of naming temporary files on some systems.
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- Some g77-specific handling of building under Microsoft operating
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systems exists, mainly in libI77/.
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