/*
    Copyright (C) 1995-1997 AROS - The Amiga Replacement OS
    $Id: sdivmod32.c,v 1.2 1997/02/03 02:58:31 ldp Exp $

    Desc: SDivMod32 - Divide two 32 bit numbers.
    Lang: english
*/
#include "utility_intern.h"

/*****************************************************************************

    NAME */
#include <proto/utility.h>

        AROS_LH2(QUAD, SDivMod32,

/*  SYNOPSIS */
        AROS_LHA(LONG, dividend, D0),
        AROS_LHA(LONG, divisor, D1),

/*  LOCATION */
        struct UtilityBase *, UtilityBase, 25, Utility)

/*  FUNCTION
        Calculates the 32-bit signed division of dividend by divisor. That
        is dividend / divisor. Will return both the quotient and the
        remainder.

    INPUTS
        dividend    -   The number to divide.
        divisor     -   The to divide by.

    RESULT
        For m68k assembly programmers:
            D0: quotient
            D1: remainder
        Others:
            The quotient is returned in the high 32 bits of the result.
            The remainder in the low 32 bits.

    NOTES
        The utility.library math functions are unlike all other utility
        functions in that they don't require the library base to be
        loaded in register A6, and they also save the values of the
        address registers A0/A1.

        This function is mainly to support assembly programers, and is
        probably of limited use to higher-level language programmers.

    EXAMPLE

    BUGS
        It is very hard for a C programmer to obtain the value of the
        remainder. In fact, its pretty near impossible.

    SEE ALSO
        SMult32(), SMult64(), UDivMod32(), UMult32(), UMult64()

    INTERNALS
        This may be handled by code in config/$(KERNEL).

    HISTORY
        29-10-95    digulla automatically created from
                            utility_lib.fd and clib/utility_protos.h

*****************************************************************************/
{
    AROS_LIBFUNC_INIT

    return dividend / divisor;

#if 0
#error Sorry, but the SDivMod32() emulation code does NOT work...
    /*
        This does NOT work. Do not even try and use this code...
    */

    UWORD a,b,c,d;
    QUAD result;
    LONG quo, rem;
    BOOL neg;

    /* Fix everything up so that -ve signs don't vanish */
    if(dividend < 0)
    {
        neg = 1; dividend = -dividend;
    }
    else
        neg = 0;

    if(divisor < 0)
    {
        neg ^= 1; divisor = -divisor;
    }

    a = dividend >> 16;
    b = dividend & 0xFFFF;
    c = divisor >> 16;
    d = divisor & 0xFFFF;

    /* See if the numerator is 32 bits or 16... */
    if(a == 0)
    {
        /* 16 bits */
        if(c != 0)
        {
            /* 16/32 -> quo = 0; rem = dividend */
            quo = 0;
            rem = dividend;
        }
        else
        {
            /* 16/16 -> can be done in native div */
            quo = b / d;
            rem = b % d;
        }
    }
    else
    {
        /* 32 bit numerator */
        if(c != 0)
        {
            /* 32 bit denominator, quo ~= a/c */
            quo = a/c;
        }
        else
        {
            /* 16 bit denominator, quo ~= (a/d) * 65536 */
            quo = (a / d) << 16;
        }
        /* Get the error */
        rem = dividend - UMult32(quo,divisor);

        /* Take the remainder down to zero */
        while(rem > 0)
        {
            quo++;
            rem -= divisor;
        }

        /* However a -ve remainder is silly,
           this also catches the case when the remainder is < 0 from the
           guess
        */
        while(rem < 0)
        {
            quo--;
            rem += divisor;
        }
    }

    return result;

#endif

    AROS_LIBFUNC_EXIT
} /* SDivMod32 */