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From: aburto@marlin.UUCP (Alfred A. Aburto)
Newsgroups: comp.sys.amiga
Subject: 68881 to C interface
Message-ID: <846@marlin.UUCP>
Date: Thu, 20-Nov-86 14:38:50 EST
Article-I.D.: marlin.846
Posted: Thu Nov 20 14:38:50 1986
Date-Received: Thu, 20-Nov-86 23:39:50 EST
Reply-To: aburto@marlin.UUCP (Alfred A. Aburto)
Distribution: net
Organization: Naval Ocean Systems Center, San Diego
Lines: 52
Keywords: 68020, 68881, Turbo-Amiga
Organizs: 68020, 68881, Turbo-Amiga, Lattice C, San Diego



Several people have asked me how one could talk to the 68020/68881 via
Lattice C.  The best solution of course would be an Amiga Lattice C compiler
version that supports the 68020/68881.  Next would be a software library
such as the mathffp.library and mathtrans.library which one could call from
C.  Finally one could write an assembly program which does 68020/68881
things that would be compiled and linked to work with a target C program. 

Its this latter approach that I can help with.  What I have is a bit of a
kludge but it does work.  A sample C test program is shown below and I'll
upload the Assembly program in a follow up message.

The sample C program :      
/**************************************/
/*  68020/68881 test program          */
/**************************************/

    extern  float  FPCP();            /* 68020/68881 Assembly program */
    main()
    {
        float ua, ub, uc, ud;
        int mc;

        mc = 1;
	ua = 0.5;
	ub = 1.75;
	uc = FPCP(mc, &ua, &ub);           /*  uc = ua + ub        */
	printf(" ua + ub = %f\n",uc);

        uc = FPCP(2, &ua, &ub);            /*  uc = ua - ub        */
	printf(" ua - ub = %f\n",uc);

        uc = FPCP(3, &ua, &ub);            /*  uc = ua * ub        */
	printf(" ua * ub = %f\n",uc);

        uc = FPCP(4, &ua, &ub);            /*  uc = ua / ub        */
	printf(" ua / ub = %f\n",uc);

        uc = FPCP(5, &ua);                 /*  uc = sin(ua)        */
	printf(" sin(ua) = %f\n",uc);

        uc = FPCP(6, &ua);                 /*  uc = cos(ua)        */
	printf(" cos(ua) = %f\n",uc);

        uc = FPCP(7, &ua, &ud);            /*  uc = sin(ua)        */
					   /*  ud = cos(ua)        */
   }
__________________________ end of program ____________________________

I'll upload the assembly program shortly........

Al Aburto