Re: [Qemu-devel] [PATCH v2 0/5] target/m68k: implement 680x0 FPU (part 3)

[Peter Maydell]

On 29 November 2017 at 13:42, Laurent Vivier <address@hidden> wrote:
> these functions come from:
>
> http://previous.alternative-system.com/
>
> http://svn.code.sf.net/p/previous/code/trunk/src/softfloat/softfloat.c
>
> This is also a modified softfloat, release 2b
> which is BSD license if I'm correct.

We can't use softfloat2b code (the part of the license that goes
"USE OF THIS SOFTWARE IS RESTRICTED TO PERSONS
AND ORGANIZATIONS [...] WHO FURTHERMORE EFFECTIVELY INDEMNIFY JOHN
HAUSER AND THE INTERNATIONAL COMPUTER SCIENCE INSTITUTE" isn't
GPL compatible).

We can use softfloat2a code, which doesn't have that indemnity clause.

> http://svn.code.sf.net/p/previous/code/trunk/src/softfloat/README.txt
>
> and MAME is GPL:
> http://mamedev.org/legal.html
>
> and Previous is a fork of Hatari (GPL), a fork of UAE (GPL)
> https://hatari.tuxfamily.org/index.html
>
> This code has also been copied to WinUAE (GPL), where softfloat has been
> copied from QEMU:
> https://github.com/tonioni/WinUAE/blob/master/softfloat/softfloat.cpp

Yes, lots of projects used the softfloat2b code without realising
it wasn't GPL compatible (including QEMU -- we had a painful job
to fix things up and convert to the 2a codebase a while back).

> But I think the bad news comes later:
>
> all the other functions (sin, cos, tan, log, exp, ...) found in previous
> (softfloat_fpsp.c) are "derived" from NeXT library FPSP:
>
> http://svn.code.sf.net/p/previous/code/trunk/src/softfloat/softfloat_fpsp.c
>
> /*============================================================================
>
>  This C source file is an extension to the SoftFloat IEC/IEEE Floating-point
>  Arithmetic Package, Release 2a.
>
>  Written by Andreas Grabher for Previous, NeXT Computer Emulator.
>
> =============================================================================*/
> ...
> /*----------------------------------------------------------------------------
> | Algorithms for transcendental functions supported by MC68881 and MC68882
> | mathematical coprocessors. The functions are derived from FPSP library.
> *----------------------------------------------------------------------------*/
>
> FPSP library can be found:
>
> https://ftp.nice.ch/pub/next/developer/hardware/m68k/
>
> And the assembly source code is not free at all:
>
> https://ftp.nice.ch/pub/next/developer/hardware/m68k/_libFPSP.1.p2.N.s/l_fpsp.h
>
>
> |               Copyright (C) Motorola, Inc. 1991
> |                       All Rights Reserved
> |
> |       THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
> |       The copyright notice above does not evidence any
> |       actual or intended publication of such source code.
>
>
> So I'm wondering what license apply to the C version found in "Previous".

Good question. It's clearly not copied code (since the FPSP library is
all native m68k assembly), but presumably it's the same algorithms
transliterated into C...

thanks
-- PMM