-rw-rw-r--  1 gray        87822 Sep 25 15:14 881.zoo


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gnu881.inf
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    GNU881.INF
    
    Some info about these libraries
    
    Michael Ritzert
    Liebermannstr.8
    5309 Meckenheim
    Germany
    ritzert@dfg.dbp.de
    
    History: most of these routines have been ported to gcc from a
    library patch to AC-Fortran i've developed a while ago. There has
    been an intermediate version compatible to John Dunning's library to
    gcc 1.34 (thank You very much, John, for the initial ports of gcc!).
    The library runs with the original Atari sfp004 in MegaSTs and the
    Boards of Weide and Lischka. It has been tested with hardware
    accelerators (the 68000-hypercache and the hypercache 030). With the
    '030 in connection to an st-compatible 68881 card, the internal caches
    of the cpu have to be switched off, due to a (documented) bug in the
    caching logic of the 68030. See pro_VME's documentation.
    
    Features: 

    The library is more or less compatible to pml, which belongs to the
    gcc.1.37-distribution of Jwahar Bammi (Thanks a lot for the great
    work You, Eric and all the others spend in that tool). It has been
    used to compile sc 6.8 and gnuplot 2.0.
    
    The library addresses the coprocessor registers directly; there is
    no linef support. If You use it in connection with MiNT, please be
    careful to start ONLY ONE process that uses the fpu since nothing
    has been implemented to overcome the mutual exclusion problem!
    
    Error handling has been implemented in a very rudimentary way (well,
    I believe it's a bit better than in pml). I make use of the fact
    that the 68881 handles floating point exceptions in a self
    consistant manner: Overflows are represented by a signed infinity,
    operations leading to undefined results like 0/0 will be represented
    by a NAN (not a number) symbol. It is also signed; but i never saw a
    negative NAN appearing. In cases where it is (a) simple and (b) not
    time critical to check these conditions, this has been implemented.
    There is no exit on the appearence due to floating point exceptions,
    due to two reasons:
    (a) the 68881 is able to use these symbols in a logical and self
    consistent manner in the computations.
    (b) there are a lot of algorithms which are not very sensitive to,
    say, floating point overflows. It would not be wise to stop the
    computation in these cases. Anyway, the user should (and will be)
    informed about floating point exceptions.
    
    The IO routines have been extended to handle Infinities and NANs.
    The original printf crashes upon the appearence of a NAN. Now,
    +-Infinity or Not A Number is written to the device (better than
    FORTRAN's stars).
    
    This library CANNOT be used on systems with a real hardware
    interface between cpu and coprocessor, i.e., STs with a PAK20, a
    hypercache030 or other 68020/68030 cards with a 68881/68882 on
    board or the TT. On these boards, the line-f commands have to be used.
    
    Installation:
    
    Add the files 881.olb (32 bit int) and 88116.olb (16 bit int) to
    $GNULIB. Link with -l881 or -l88116.
    
    Conclusion:
    
    We are in urgend need of a standardized floating point interface for
    ALL Motorola based Ataris. A few months ago, it has been
    demonstrated in an article published in the c't magazine that a full
    line-f floating point interface can easily be implemented in any ST,
    even those, whose TOS abuses line-f.
    
    Enjoy,
    
    Michael Ritzert