int
sgl_frem (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2,
	  sgl_floating_point * dstptr, unsigned int *status)
{
	register unsigned int opnd1, opnd2, result;
	register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount;
	register boolean roundup = FALSE;

	opnd1 = *srcptr1;
	opnd2 = *srcptr2;
	/*
	 * check first operand for NaN's or infinity
	 */
	if ((opnd1_exponent = Sgl_exponent(opnd1)) == SGL_INFINITY_EXPONENT) {
		if (Sgl_iszero_mantissa(opnd1)) {
			if (Sgl_isnotnan(opnd2)) {
				/* invalid since first operand is infinity */
				if (Is_invalidtrap_enabled()) 
                                	return(INVALIDEXCEPTION);
                                Set_invalidflag();
                                Sgl_makequietnan(result);
				*dstptr = result;
				return(NOEXCEPTION);
			}
		}
		else {
                	/*
                 	 * is NaN; signaling or quiet?
                 	 */
                	if (Sgl_isone_signaling(opnd1)) {
                        	/* trap if INVALIDTRAP enabled */
                        	if (Is_invalidtrap_enabled()) 
                            		return(INVALIDEXCEPTION);
                        	/* make NaN quiet */
                        	Set_invalidflag();
                        	Sgl_set_quiet(opnd1);
                	}
			/* 
			 * is second operand a signaling NaN? 
			 */
			else if (Sgl_is_signalingnan(opnd2)) {
                        	/* trap if INVALIDTRAP enabled */
                        	if (Is_invalidtrap_enabled()) 
                            		return(INVALIDEXCEPTION);
                        	/* make NaN quiet */
                        	Set_invalidflag();
                        	Sgl_set_quiet(opnd2);
                		*dstptr = opnd2;
                		return(NOEXCEPTION);
			}
                	/*
                 	 * return quiet NaN
                 	 */
                	*dstptr = opnd1;
                	return(NOEXCEPTION);
		}
	} 
	/*
	 * check second operand for NaN's or infinity
	 */
	if ((opnd2_exponent = Sgl_exponent(opnd2)) == SGL_INFINITY_EXPONENT) {
		if (Sgl_iszero_mantissa(opnd2)) {
			/*
			 * return first operand
			 */
                	*dstptr = opnd1;
			return(NOEXCEPTION);
		}
                /*
                 * is NaN; signaling or quiet?
                 */
                if (Sgl_isone_signaling(opnd2)) {
                        /* trap if INVALIDTRAP enabled */
                        if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                        /* make NaN quiet */
                        Set_invalidflag();
                        Sgl_set_quiet(opnd2);
                }
                /*
                 * return quiet NaN
                 */
                *dstptr = opnd2;
                return(NOEXCEPTION);
	}
	/*
	 * check second operand for zero
	 */
	if (Sgl_iszero_exponentmantissa(opnd2)) {
		/* invalid since second operand is zero */
		if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                Set_invalidflag();
                Sgl_makequietnan(result);
		*dstptr = result;
		return(NOEXCEPTION);
	}

	/* 
	 * get sign of result
	 */
	result = opnd1;  

	/* 
	 * check for denormalized operands
	 */
	if (opnd1_exponent == 0) {
		/* check for zero */
		if (Sgl_iszero_mantissa(opnd1)) {
			*dstptr = opnd1;
			return(NOEXCEPTION);
		}
		/* normalize, then continue */
		opnd1_exponent = 1;
		Sgl_normalize(opnd1,opnd1_exponent);
	}
	else {
		Sgl_clear_signexponent_set_hidden(opnd1);
	}
	if (opnd2_exponent == 0) {
		/* normalize, then continue */
		opnd2_exponent = 1;
		Sgl_normalize(opnd2,opnd2_exponent);
	}
	else {
		Sgl_clear_signexponent_set_hidden(opnd2);
	}

	/* find result exponent and divide step loop count */
	dest_exponent = opnd2_exponent - 1;
	stepcount = opnd1_exponent - opnd2_exponent;

	/*
	 * check for opnd1/opnd2 < 1
	 */
	if (stepcount < 0) {
		/*
		 * check for opnd1/opnd2 > 1/2
		 *
		 * In this case n will round to 1, so 
		 *    r = opnd1 - opnd2 
		 */
		if (stepcount == -1 && Sgl_isgreaterthan(opnd1,opnd2)) {
			Sgl_all(result) = ~Sgl_all(result);   /* set sign */
			/* align opnd2 with opnd1 */
			Sgl_leftshiftby1(opnd2); 
			Sgl_subtract(opnd2,opnd1,opnd2);
			/* now normalize */
                	while (Sgl_iszero_hidden(opnd2)) {
                        	Sgl_leftshiftby1(opnd2);
                        	dest_exponent--;
			}
			Sgl_set_exponentmantissa(result,opnd2);
			goto testforunderflow;
		}
		/*
		 * opnd1/opnd2 <= 1/2
		 *
		 * In this case n will round to zero, so 
		 *    r = opnd1
		 */
		Sgl_set_exponentmantissa(result,opnd1);
		dest_exponent = opnd1_exponent;
		goto testforunderflow;
	}

	/*
	 * Generate result
	 *
	 * Do iterative subtract until remainder is less than operand 2.
	 */
	while (stepcount-- > 0 && Sgl_all(opnd1)) {
		if (Sgl_isnotlessthan(opnd1,opnd2))
			Sgl_subtract(opnd1,opnd2,opnd1);
		Sgl_leftshiftby1(opnd1);
	}
	/*
	 * Do last subtract, then determine which way to round if remainder 
	 * is exactly 1/2 of opnd2 
	 */
	if (Sgl_isnotlessthan(opnd1,opnd2)) {
		Sgl_subtract(opnd1,opnd2,opnd1);
		roundup = TRUE;
	}
	if (stepcount > 0 || Sgl_iszero(opnd1)) {
		/* division is exact, remainder is zero */
		Sgl_setzero_exponentmantissa(result);
		*dstptr = result;
		return(NOEXCEPTION);
	}

	/* 
	 * Check for cases where opnd1/opnd2 < n 
	 *
	 * In this case the result's sign will be opposite that of
	 * opnd1.  The mantissa also needs some correction.
	 */
	Sgl_leftshiftby1(opnd1);
	if (Sgl_isgreaterthan(opnd1,opnd2)) {
		Sgl_invert_sign(result);
		Sgl_subtract((opnd2<<1),opnd1,opnd1);
	}
	/* check for remainder being exactly 1/2 of opnd2 */
	else if (Sgl_isequal(opnd1,opnd2) && roundup) { 
		Sgl_invert_sign(result);
	}

	/* normalize result's mantissa */
        while (Sgl_iszero_hidden(opnd1)) {
                dest_exponent--;
                Sgl_leftshiftby1(opnd1);
        }
	Sgl_set_exponentmantissa(result,opnd1);

        /* 
         * Test for underflow
         */
    testforunderflow:
	if (dest_exponent <= 0) {
                /* trap if UNDERFLOWTRAP enabled */
                if (Is_underflowtrap_enabled()) {
                        /*
                         * Adjust bias of result
                         */
                        Sgl_setwrapped_exponent(result,dest_exponent,unfl);
			*dstptr = result;
			/* frem is always exact */
			return(UNDERFLOWEXCEPTION);
                }
                /*
                 * denormalize result or set to signed zero
                 */
                if (dest_exponent >= (1 - SGL_P)) {
			Sgl_rightshift_exponentmantissa(result,1-dest_exponent);
                }
                else {
			Sgl_setzero_exponentmantissa(result);
		}
	}
	else Sgl_set_exponent(result,dest_exponent);
	*dstptr = result;
	return(NOEXCEPTION);
}
示例#2
0
int
sgl_fmpy(
    sgl_floating_point *srcptr1,
    sgl_floating_point *srcptr2,
    sgl_floating_point *dstptr,
    unsigned int *status)
{
    register unsigned int opnd1, opnd2, opnd3, result;
    register int dest_exponent, count;
    register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE;
    boolean is_tiny;

    opnd1 = *srcptr1;
    opnd2 = *srcptr2;
    /*
     * set sign bit of result
     */
    if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) Sgl_setnegativezero(result);
    else Sgl_setzero(result);
    /*
     * check first operand for NaN's or infinity
     */
    if (Sgl_isinfinity_exponent(opnd1)) {
        if (Sgl_iszero_mantissa(opnd1)) {
            if (Sgl_isnotnan(opnd2)) {
                if (Sgl_iszero_exponentmantissa(opnd2)) {
                    /*
                     * invalid since operands are infinity
                     * and zero
                     */
                    if (Is_invalidtrap_enabled())
                        return(INVALIDEXCEPTION);
                    Set_invalidflag();
                    Sgl_makequietnan(result);
                    *dstptr = result;
                    return(NOEXCEPTION);
                }
                /*
                 * return infinity
                 */
                Sgl_setinfinity_exponentmantissa(result);
                *dstptr = result;
                return(NOEXCEPTION);
            }
        }
        else {
            /*
             * is NaN; signaling or quiet?
             */
            if (Sgl_isone_signaling(opnd1)) {
                /* trap if INVALIDTRAP enabled */
                if (Is_invalidtrap_enabled())
                    return(INVALIDEXCEPTION);
                /* make NaN quiet */
                Set_invalidflag();
                Sgl_set_quiet(opnd1);
            }
            /*
             * is second operand a signaling NaN?
             */
            else if (Sgl_is_signalingnan(opnd2)) {
                /* trap if INVALIDTRAP enabled */
                if (Is_invalidtrap_enabled())
                    return(INVALIDEXCEPTION);
                /* make NaN quiet */
                Set_invalidflag();
                Sgl_set_quiet(opnd2);
                *dstptr = opnd2;
                return(NOEXCEPTION);
            }
            /*
             * return quiet NaN
             */
            *dstptr = opnd1;
            return(NOEXCEPTION);
        }
    }
    /*
     * check second operand for NaN's or infinity
     */
    if (Sgl_isinfinity_exponent(opnd2)) {
        if (Sgl_iszero_mantissa(opnd2)) {
            if (Sgl_iszero_exponentmantissa(opnd1)) {
                /* invalid since operands are zero & infinity */
                if (Is_invalidtrap_enabled())
                    return(INVALIDEXCEPTION);
                Set_invalidflag();
                Sgl_makequietnan(opnd2);
                *dstptr = opnd2;
                return(NOEXCEPTION);
            }
            /*
             * return infinity
             */
            Sgl_setinfinity_exponentmantissa(result);
            *dstptr = result;
            return(NOEXCEPTION);
        }
        /*
         * is NaN; signaling or quiet?
         */
        if (Sgl_isone_signaling(opnd2)) {
            /* trap if INVALIDTRAP enabled */
            if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);

            /* make NaN quiet */
            Set_invalidflag();
            Sgl_set_quiet(opnd2);
        }
        /*
         * return quiet NaN
         */
        *dstptr = opnd2;
        return(NOEXCEPTION);
    }
    /*
     * Generate exponent
     */
    dest_exponent = Sgl_exponent(opnd1) + Sgl_exponent(opnd2) - SGL_BIAS;

    /*
     * Generate mantissa
     */
    if (Sgl_isnotzero_exponent(opnd1)) {
        /* set hidden bit */
        Sgl_clear_signexponent_set_hidden(opnd1);
    }
    else {
        /* check for zero */
        if (Sgl_iszero_mantissa(opnd1)) {
            Sgl_setzero_exponentmantissa(result);
            *dstptr = result;
            return(NOEXCEPTION);
        }
        /* is denormalized, adjust exponent */
        Sgl_clear_signexponent(opnd1);
        Sgl_leftshiftby1(opnd1);
        Sgl_normalize(opnd1,dest_exponent);
    }
    /* opnd2 needs to have hidden bit set with msb in hidden bit */
    if (Sgl_isnotzero_exponent(opnd2)) {
        Sgl_clear_signexponent_set_hidden(opnd2);
    }
    else {
        /* check for zero */
        if (Sgl_iszero_mantissa(opnd2)) {
            Sgl_setzero_exponentmantissa(result);
            *dstptr = result;
            return(NOEXCEPTION);
        }
        /* is denormalized; want to normalize */
        Sgl_clear_signexponent(opnd2);
        Sgl_leftshiftby1(opnd2);
        Sgl_normalize(opnd2,dest_exponent);
    }

    /* Multiply two source mantissas together */

    Sgl_leftshiftby4(opnd2);     /* make room for guard bits */
    Sgl_setzero(opnd3);
    /*
     * Four bits at a time are inspected in each loop, and a
     * simple shift and add multiply algorithm is used.
     */
    for (count=1; count<SGL_P; count+=4) {
        stickybit |= Slow4(opnd3);
        Sgl_rightshiftby4(opnd3);
        if (Sbit28(opnd1)) Sall(opnd3) += (Sall(opnd2) << 3);
        if (Sbit29(opnd1)) Sall(opnd3) += (Sall(opnd2) << 2);
        if (Sbit30(opnd1)) Sall(opnd3) += (Sall(opnd2) << 1);
        if (Sbit31(opnd1)) Sall(opnd3) += Sall(opnd2);
        Sgl_rightshiftby4(opnd1);
    }
    /* make sure result is left-justified */
    if (Sgl_iszero_sign(opnd3)) {
        Sgl_leftshiftby1(opnd3);
    }
    else {
        /* result mantissa >= 2. */
        dest_exponent++;
    }
    /* check for denormalized result */
    while (Sgl_iszero_sign(opnd3)) {
        Sgl_leftshiftby1(opnd3);
        dest_exponent--;
    }
    /*
     * check for guard, sticky and inexact bits
     */
    stickybit |= Sgl_all(opnd3) << (SGL_BITLENGTH - SGL_EXP_LENGTH + 1);
    guardbit = Sbit24(opnd3);
    inexact = guardbit | stickybit;

    /* re-align mantissa */
    Sgl_rightshiftby8(opnd3);

    /*
     * round result
     */
    if (inexact && (dest_exponent>0 || Is_underflowtrap_enabled())) {
        Sgl_clear_signexponent(opnd3);
        switch (Rounding_mode()) {
        case ROUNDPLUS:
            if (Sgl_iszero_sign(result))
                Sgl_increment(opnd3);
            break;
        case ROUNDMINUS:
            if (Sgl_isone_sign(result))
                Sgl_increment(opnd3);
            break;
        case ROUNDNEAREST:
            if (guardbit) {
                if (stickybit || Sgl_isone_lowmantissa(opnd3))
                    Sgl_increment(opnd3);
            }
        }
        if (Sgl_isone_hidden(opnd3)) dest_exponent++;
    }
    Sgl_set_mantissa(result,opnd3);

    /*
     * Test for overflow
     */
    if (dest_exponent >= SGL_INFINITY_EXPONENT) {
        /* trap if OVERFLOWTRAP enabled */
        if (Is_overflowtrap_enabled()) {
            /*
             * Adjust bias of result
             */
            Sgl_setwrapped_exponent(result,dest_exponent,ovfl);
            *dstptr = result;
            if (inexact)
                if (Is_inexacttrap_enabled())
                    return(OVERFLOWEXCEPTION | INEXACTEXCEPTION);
                else Set_inexactflag();
            return(OVERFLOWEXCEPTION);
        }
        inexact = TRUE;
        Set_overflowflag();
        /* set result to infinity or largest number */
        Sgl_setoverflow(result);
    }
    /*
     * Test for underflow
     */
    else if (dest_exponent <= 0) {
        /* trap if UNDERFLOWTRAP enabled */
        if (Is_underflowtrap_enabled()) {
            /*
             * Adjust bias of result
             */
            Sgl_setwrapped_exponent(result,dest_exponent,unfl);
            *dstptr = result;
            if (inexact)
                if (Is_inexacttrap_enabled())
                    return(UNDERFLOWEXCEPTION | INEXACTEXCEPTION);
                else Set_inexactflag();
            return(UNDERFLOWEXCEPTION);
        }

        /* Determine if should set underflow flag */
        is_tiny = TRUE;
        if (dest_exponent == 0 && inexact) {
            switch (Rounding_mode()) {
            case ROUNDPLUS:
                if (Sgl_iszero_sign(result)) {
                    Sgl_increment(opnd3);
                    if (Sgl_isone_hiddenoverflow(opnd3))
                        is_tiny = FALSE;
                    Sgl_decrement(opnd3);
                }
                break;
            case ROUNDMINUS:
                if (Sgl_isone_sign(result)) {
                    Sgl_increment(opnd3);
                    if (Sgl_isone_hiddenoverflow(opnd3))
                        is_tiny = FALSE;
                    Sgl_decrement(opnd3);
                }
                break;
            case ROUNDNEAREST:
                if (guardbit && (stickybit ||
                                 Sgl_isone_lowmantissa(opnd3))) {
                    Sgl_increment(opnd3);
                    if (Sgl_isone_hiddenoverflow(opnd3))
                        is_tiny = FALSE;
                    Sgl_decrement(opnd3);
                }
                break;
            }
        }

        /*
         * denormalize result or set to signed zero
         */
        stickybit = inexact;
        Sgl_denormalize(opnd3,dest_exponent,guardbit,stickybit,inexact);

        /* return zero or smallest number */
        if (inexact) {
            switch (Rounding_mode()) {
            case ROUNDPLUS:
                if (Sgl_iszero_sign(result)) {
                    Sgl_increment(opnd3);
                }
                break;
            case ROUNDMINUS:
                if (Sgl_isone_sign(result)) {
                    Sgl_increment(opnd3);
                }
                break;
            case ROUNDNEAREST:
                if (guardbit && (stickybit ||
                                 Sgl_isone_lowmantissa(opnd3))) {
                    Sgl_increment(opnd3);
                }
                break;
            }
            if (is_tiny) Set_underflowflag();
        }
        Sgl_set_exponentmantissa(result,opnd3);
    }
    else Sgl_set_exponent(result,dest_exponent);
    *dstptr = result;

    /* check for inexact */
    if (inexact) {
        if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
        else Set_inexactflag();
    }
    return(NOEXCEPTION);
}
示例#3
0
文件: sfadd.c 项目: 1x23/unifi-gpl
/*
 * Single_add: add two single precision values.
 */
int
sgl_fadd(
    sgl_floating_point *leftptr,
    sgl_floating_point *rightptr,
    sgl_floating_point *dstptr,
    unsigned int *status)
    {
    register unsigned int left, right, result, extent;
    register unsigned int signless_upper_left, signless_upper_right, save;
    
    
    register int result_exponent, right_exponent, diff_exponent;
    register int sign_save, jumpsize;
    register boolean inexact = FALSE;
    register boolean underflowtrap;
        
    /* Create local copies of the numbers */
    left = *leftptr;
    right = *rightptr;

    /* A zero "save" helps discover equal operands (for later),  *
     * and is used in swapping operands (if needed).             */
    Sgl_xortointp1(left,right,/*to*/save);

    /*
     * check first operand for NaN's or infinity
     */
    if ((result_exponent = Sgl_exponent(left)) == SGL_INFINITY_EXPONENT)
	{
	if (Sgl_iszero_mantissa(left)) 
	    {
	    if (Sgl_isnotnan(right)) 
		{
		if (Sgl_isinfinity(right) && save!=0) 
		    {
		    /* 
		     * invalid since operands are opposite signed infinity's
		     */
		    if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                    Set_invalidflag();
                    Sgl_makequietnan(result);
		    *dstptr = result;
		    return(NOEXCEPTION);
		    }
		/*
	 	 * return infinity
	 	 */
		*dstptr = left;
		return(NOEXCEPTION);
		}
	    }
	else 
	    {
            /*
             * is NaN; signaling or quiet?
             */
            if (Sgl_isone_signaling(left)) 
		{
               	/* trap if INVALIDTRAP enabled */
		if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
        	/* make NaN quiet */
        	Set_invalidflag();
        	Sgl_set_quiet(left);
        	}
	    /* 
	     * is second operand a signaling NaN? 
	     */
	    else if (Sgl_is_signalingnan(right)) 
		{
        	/* trap if INVALIDTRAP enabled */
               	if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
		/* make NaN quiet */
		Set_invalidflag();
		Sgl_set_quiet(right);
		*dstptr = right;
		return(NOEXCEPTION);
		}
	    /*
 	     * return quiet NaN
 	     */
 	    *dstptr = left;
 	    return(NOEXCEPTION);
	    }
	} /* End left NaN or Infinity processing */
    /*
     * check second operand for NaN's or infinity
     */
    if (Sgl_isinfinity_exponent(right)) 
	{
	if (Sgl_iszero_mantissa(right)) 
	    {
	    /* return infinity */
	    *dstptr = right;
	    return(NOEXCEPTION);
	    }
        /*
         * is NaN; signaling or quiet?
         */
        if (Sgl_isone_signaling(right)) 
	    {
            /* trap if INVALIDTRAP enabled */
	    if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
	    /* make NaN quiet */
	    Set_invalidflag();
	    Sgl_set_quiet(right);
	    }
	/*
	 * return quiet NaN
 	 */
	*dstptr = right;
	return(NOEXCEPTION);
    	} /* End right NaN or Infinity processing */

    /* Invariant: Must be dealing with finite numbers */

    /* Compare operands by removing the sign */
    Sgl_copytoint_exponentmantissa(left,signless_upper_left);
    Sgl_copytoint_exponentmantissa(right,signless_upper_right);

    /* sign difference selects add or sub operation. */
    if(Sgl_ismagnitudeless(signless_upper_left,signless_upper_right))
	{
	/* Set the left operand to the larger one by XOR swap *
	 *  First finish the first word using "save"          */
	Sgl_xorfromintp1(save,right,/*to*/right);
	Sgl_xorfromintp1(save,left,/*to*/left);
	result_exponent = Sgl_exponent(left);
	}
    /* Invariant:  left is not smaller than right. */ 

    if((right_exponent = Sgl_exponent(right)) == 0)
        {
	/* Denormalized operands.  First look for zeroes */
	if(Sgl_iszero_mantissa(right)) 
	    {
	    /* right is zero */
	    if(Sgl_iszero_exponentmantissa(left))
		{
		/* Both operands are zeros */
		if(Is_rounding_mode(ROUNDMINUS))
		    {
		    Sgl_or_signs(left,/*with*/right);
		    }
		else
		    {
		    Sgl_and_signs(left,/*with*/right);
		    }
		}
	    else 
		{
		/* Left is not a zero and must be the result.  Trapped
		 * underflows are signaled if left is denormalized.  Result
		 * is always exact. */
		if( (result_exponent == 0) && Is_underflowtrap_enabled() )
		    {
		    /* need to normalize results mantissa */
	    	    sign_save = Sgl_signextendedsign(left);
		    Sgl_leftshiftby1(left);
		    Sgl_normalize(left,result_exponent);
		    Sgl_set_sign(left,/*using*/sign_save);
		    Sgl_setwrapped_exponent(left,result_exponent,unfl);
		    *dstptr = left;
		    return(UNDERFLOWEXCEPTION);
		    }
		}
	    *dstptr = left;
	    return(NOEXCEPTION);
	    }

	/* Neither are zeroes */
	Sgl_clear_sign(right);	/* Exponent is already cleared */
	if(result_exponent == 0 )
	    {
	    /* Both operands are denormalized.  The result must be exact
	     * and is simply calculated.  A sum could become normalized and a
	     * difference could cancel to a true zero. */
	    if( (/*signed*/int) save < 0 )
		{
		Sgl_subtract(left,/*minus*/right,/*into*/result);
		if(Sgl_iszero_mantissa(result))
		    {
		    if(Is_rounding_mode(ROUNDMINUS))
			{
			Sgl_setone_sign(result);
			}
		    else
			{
			Sgl_setzero_sign(result);
			}
		    *dstptr = result;
		    return(NOEXCEPTION);
		    }
		}
	    else
		{
		Sgl_addition(left,right,/*into*/result);
		if(Sgl_isone_hidden(result))
		    {
		    *dstptr = result;
		    return(NOEXCEPTION);
		    }
		}
	    if(Is_underflowtrap_enabled())
		{
		/* need to normalize result */
	    	sign_save = Sgl_signextendedsign(result);
		Sgl_leftshiftby1(result);
		Sgl_normalize(result,result_exponent);
		Sgl_set_sign(result,/*using*/sign_save);
                Sgl_setwrapped_exponent(result,result_exponent,unfl);
		*dstptr = result;
		return(UNDERFLOWEXCEPTION);
		}
	    *dstptr = result;
	    return(NOEXCEPTION);
	    }
	right_exponent = 1;	/* Set exponent to reflect different bias
				 * with denomalized numbers. */
	}
    else
	{
	Sgl_clear_signexponent_set_hidden(right);
	}
    Sgl_clear_exponent_set_hidden(left);
    diff_exponent = result_exponent - right_exponent;

    /* 
     * Special case alignment of operands that would force alignment 
     * beyond the extent of the extension.  A further optimization
     * could special case this but only reduces the path length for this
     * infrequent case.
     */
    if(diff_exponent > SGL_THRESHOLD)
	{
	diff_exponent = SGL_THRESHOLD;
	}
    
    /* Align right operand by shifting to right */
    Sgl_right_align(/*operand*/right,/*shifted by*/diff_exponent,
     /*and lower to*/extent);

    /* Treat sum and difference of the operands separately. */
    if( (/*signed*/int) save < 0 )
	{
	/*
	 * Difference of the two operands.  Their can be no overflow.  A
	 * borrow can occur out of the hidden bit and force a post
	 * normalization phase.
	 */
	Sgl_subtract_withextension(left,/*minus*/right,/*with*/extent,/*into*/result);
	if(Sgl_iszero_hidden(result))
	    {
	    /* Handle normalization */
	    /* A straight foward algorithm would now shift the result
	     * and extension left until the hidden bit becomes one.  Not
	     * all of the extension bits need participate in the shift.
	     * Only the two most significant bits (round and guard) are
	     * needed.  If only a single shift is needed then the guard
	     * bit becomes a significant low order bit and the extension
	     * must participate in the rounding.  If more than a single 
	     * shift is needed, then all bits to the right of the guard 
	     * bit are zeros, and the guard bit may or may not be zero. */
	    sign_save = Sgl_signextendedsign(result);
            Sgl_leftshiftby1_withextent(result,extent,result);

            /* Need to check for a zero result.  The sign and exponent
	     * fields have already been zeroed.  The more efficient test
	     * of the full object can be used.
	     */
    	    if(Sgl_iszero(result))
		/* Must have been "x-x" or "x+(-x)". */
		{
		if(Is_rounding_mode(ROUNDMINUS)) Sgl_setone_sign(result);
		*dstptr = result;
		return(NOEXCEPTION);
		}
	    result_exponent--;
	    /* Look to see if normalization is finished. */
	    if(Sgl_isone_hidden(result))
		{
		if(result_exponent==0)
		    {
		    /* Denormalized, exponent should be zero.  Left operand *
 		     * was normalized, so extent (guard, round) was zero    */
		    goto underflow;
		    }
		else
		    {
		    /* No further normalization is needed. */
		    Sgl_set_sign(result,/*using*/sign_save);
	    	    Ext_leftshiftby1(extent);
		    goto round;
		    }
		}

	    /* Check for denormalized, exponent should be zero.  Left    * 
	     * operand was normalized, so extent (guard, round) was zero */
	    if(!(underflowtrap = Is_underflowtrap_enabled()) &&
	       result_exponent==0) goto underflow;

	    /* Shift extension to complete one bit of normalization and
	     * update exponent. */
	    Ext_leftshiftby1(extent);

	    /* Discover first one bit to determine shift amount.  Use a
	     * modified binary search.  We have already shifted the result
	     * one position right and still not found a one so the remainder
	     * of the extension must be zero and simplifies rounding. */
	    /* Scan bytes */
	    while(Sgl_iszero_hiddenhigh7mantissa(result))
		{
		Sgl_leftshiftby8(result);
		if((result_exponent -= 8) <= 0  && !underflowtrap)
		    goto underflow;
		}
	    /* Now narrow it down to the nibble */
	    if(Sgl_iszero_hiddenhigh3mantissa(result))
		{
		/* The lower nibble contains the normalizing one */
		Sgl_leftshiftby4(result);
		if((result_exponent -= 4) <= 0 && !underflowtrap)
		    goto underflow;
		}
	    /* Select case were first bit is set (already normalized)
	     * otherwise select the proper shift. */
	    if((jumpsize = Sgl_hiddenhigh3mantissa(result)) > 7)
		{
		/* Already normalized */
		if(result_exponent <= 0) goto underflow;
		Sgl_set_sign(result,/*using*/sign_save);
		Sgl_set_exponent(result,/*using*/result_exponent);
		*dstptr = result;
		return(NOEXCEPTION);
		}
	    Sgl_sethigh4bits(result,/*using*/sign_save);
	    switch(jumpsize) 
		{
		case 1:
		    {
		    Sgl_leftshiftby3(result);
		    result_exponent -= 3;
		    break;
		    }
		case 2:
		case 3:
		    {
		    Sgl_leftshiftby2(result);
		    result_exponent -= 2;
		    break;
		    }
		case 4:
		case 5:
		case 6:
		case 7:
		    {
		    Sgl_leftshiftby1(result);
		    result_exponent -= 1;
		    break;
		    }
		}
	    if(result_exponent > 0) 
		{
		Sgl_set_exponent(result,/*using*/result_exponent);
		*dstptr = result;
		return(NOEXCEPTION); /* Sign bit is already set */
		}
	    /* Fixup potential underflows */
	  underflow:
	    if(Is_underflowtrap_enabled())
		{
		Sgl_set_sign(result,sign_save);
                Sgl_setwrapped_exponent(result,result_exponent,unfl);
		*dstptr = result;
		/* inexact = FALSE; */
		return(UNDERFLOWEXCEPTION);
		}
	    /* 
	     * Since we cannot get an inexact denormalized result,
	     * we can now return.
	     */
	    Sgl_right_align(result,/*by*/(1-result_exponent),extent);
	    Sgl_clear_signexponent(result);
	    Sgl_set_sign(result,sign_save);
	    *dstptr = result;
	    return(NOEXCEPTION);
	    } /* end if(hidden...)... */
	/* Fall through and round */
	} /* end if(save < 0)... */
    else 
	{
	/* Add magnitudes */
	Sgl_addition(left,right,/*to*/result);
	if(Sgl_isone_hiddenoverflow(result))
	    {
	    /* Prenormalization required. */
	    Sgl_rightshiftby1_withextent(result,extent,extent);
	    Sgl_arithrightshiftby1(result);
	    result_exponent++;
	    } /* end if hiddenoverflow... */
	} /* end else ...add magnitudes... */
    
    /* Round the result.  If the extension is all zeros,then the result is
     * exact.  Otherwise round in the correct direction.  No underflow is
     * possible. If a postnormalization is necessary, then the mantissa is
     * all zeros so no shift is needed. */
  round:
    if(Ext_isnotzero(extent))
	{
	inexact = TRUE;
	switch(Rounding_mode())
	    {
	    case ROUNDNEAREST: /* The default. */
	    if(Ext_isone_sign(extent))
		{
		/* at least 1/2 ulp */
		if(Ext_isnotzero_lower(extent)  ||
		  Sgl_isone_lowmantissa(result))
		    {
		    /* either exactly half way and odd or more than 1/2ulp */
		    Sgl_increment(result);
		    }
		}
	    break;

	    case ROUNDPLUS:
	    if(Sgl_iszero_sign(result))
		{
		/* Round up positive results */
		Sgl_increment(result);
		}
	    break;
	    
	    case ROUNDMINUS:
	    if(Sgl_isone_sign(result))
		{
		/* Round down negative results */
		Sgl_increment(result);
		}
	    
	    case ROUNDZERO:;
	    /* truncate is simple */
	    } /* end switch... */
	if(Sgl_isone_hiddenoverflow(result)) result_exponent++;
	}
    if(result_exponent == SGL_INFINITY_EXPONENT)
        {
        /* Overflow */
        if(Is_overflowtrap_enabled())
	    {
	    Sgl_setwrapped_exponent(result,result_exponent,ovfl);
	    *dstptr = result;
	    if (inexact)
		if (Is_inexacttrap_enabled())
		    return(OVERFLOWEXCEPTION | INEXACTEXCEPTION);
		else Set_inexactflag();
	    return(OVERFLOWEXCEPTION);
	    }
        else
	    {
	    Set_overflowflag();
	    inexact = TRUE;
	    Sgl_setoverflow(result);
	    }
	}
    else Sgl_set_exponent(result,result_exponent);
    *dstptr = result;
    if(inexact) 
	if(Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
	else Set_inexactflag();
    return(NOEXCEPTION);
    }
示例#4
0
int
sgl_frem (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2,
	  sgl_floating_point * dstptr, unsigned int *status)
{
	register unsigned int opnd1, opnd2, result;
	register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount;
	register boolean roundup = FALSE;

	opnd1 = *srcptr1;
	opnd2 = *srcptr2;
	if ((opnd1_exponent = Sgl_exponent(opnd1)) == SGL_INFINITY_EXPONENT) {
		if (Sgl_iszero_mantissa(opnd1)) {
			if (Sgl_isnotnan(opnd2)) {
				
				if (Is_invalidtrap_enabled()) 
                                	return(INVALIDEXCEPTION);
                                Set_invalidflag();
                                Sgl_makequietnan(result);
				*dstptr = result;
				return(NOEXCEPTION);
			}
		}
		else {
                	if (Sgl_isone_signaling(opnd1)) {
                        	
                        	if (Is_invalidtrap_enabled()) 
                            		return(INVALIDEXCEPTION);
                        	
                        	Set_invalidflag();
                        	Sgl_set_quiet(opnd1);
                	}
			else if (Sgl_is_signalingnan(opnd2)) {
                        	
                        	if (Is_invalidtrap_enabled()) 
                            		return(INVALIDEXCEPTION);
                        	
                        	Set_invalidflag();
                        	Sgl_set_quiet(opnd2);
                		*dstptr = opnd2;
                		return(NOEXCEPTION);
			}
                	*dstptr = opnd1;
                	return(NOEXCEPTION);
		}
	} 
	if ((opnd2_exponent = Sgl_exponent(opnd2)) == SGL_INFINITY_EXPONENT) {
		if (Sgl_iszero_mantissa(opnd2)) {
                	*dstptr = opnd1;
			return(NOEXCEPTION);
		}
                if (Sgl_isone_signaling(opnd2)) {
                        
                        if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                        
                        Set_invalidflag();
                        Sgl_set_quiet(opnd2);
                }
                *dstptr = opnd2;
                return(NOEXCEPTION);
	}
	if (Sgl_iszero_exponentmantissa(opnd2)) {
		
		if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                Set_invalidflag();
                Sgl_makequietnan(result);
		*dstptr = result;
		return(NOEXCEPTION);
	}

	result = opnd1;  

	if (opnd1_exponent == 0) {
		
		if (Sgl_iszero_mantissa(opnd1)) {
			*dstptr = opnd1;
			return(NOEXCEPTION);
		}
		
		opnd1_exponent = 1;
		Sgl_normalize(opnd1,opnd1_exponent);
	}
	else {
		Sgl_clear_signexponent_set_hidden(opnd1);
	}
	if (opnd2_exponent == 0) {
		
		opnd2_exponent = 1;
		Sgl_normalize(opnd2,opnd2_exponent);
	}
	else {
		Sgl_clear_signexponent_set_hidden(opnd2);
	}

	
	dest_exponent = opnd2_exponent - 1;
	stepcount = opnd1_exponent - opnd2_exponent;

	if (stepcount < 0) {
		if (stepcount == -1 && Sgl_isgreaterthan(opnd1,opnd2)) {
			Sgl_all(result) = ~Sgl_all(result);   
			
			Sgl_leftshiftby1(opnd2); 
			Sgl_subtract(opnd2,opnd1,opnd2);
			
                	while (Sgl_iszero_hidden(opnd2)) {
                        	Sgl_leftshiftby1(opnd2);
                        	dest_exponent--;
			}
			Sgl_set_exponentmantissa(result,opnd2);
			goto testforunderflow;
		}
		Sgl_set_exponentmantissa(result,opnd1);
		dest_exponent = opnd1_exponent;
		goto testforunderflow;
	}

	while (stepcount-- > 0 && Sgl_all(opnd1)) {
		if (Sgl_isnotlessthan(opnd1,opnd2))
			Sgl_subtract(opnd1,opnd2,opnd1);
		Sgl_leftshiftby1(opnd1);
	}
	if (Sgl_isnotlessthan(opnd1,opnd2)) {
		Sgl_subtract(opnd1,opnd2,opnd1);
		roundup = TRUE;
	}
	if (stepcount > 0 || Sgl_iszero(opnd1)) {
		
		Sgl_setzero_exponentmantissa(result);
		*dstptr = result;
		return(NOEXCEPTION);
	}

	Sgl_leftshiftby1(opnd1);
	if (Sgl_isgreaterthan(opnd1,opnd2)) {
		Sgl_invert_sign(result);
		Sgl_subtract((opnd2<<1),opnd1,opnd1);
	}
	
	else if (Sgl_isequal(opnd1,opnd2) && roundup) { 
		Sgl_invert_sign(result);
	}

	
        while (Sgl_iszero_hidden(opnd1)) {
                dest_exponent--;
                Sgl_leftshiftby1(opnd1);
        }
	Sgl_set_exponentmantissa(result,opnd1);

    testforunderflow:
	if (dest_exponent <= 0) {
                
                if (Is_underflowtrap_enabled()) {
                        Sgl_setwrapped_exponent(result,dest_exponent,unfl);
			*dstptr = result;
			
			return(UNDERFLOWEXCEPTION);
                }
                if (dest_exponent >= (1 - SGL_P)) {
			Sgl_rightshift_exponentmantissa(result,1-dest_exponent);
                }
                else {
			Sgl_setzero_exponentmantissa(result);
		}
	}
	else Sgl_set_exponent(result,dest_exponent);
	*dstptr = result;
	return(NOEXCEPTION);
}
示例#5
0
int
sgl_fdiv (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2,
	  sgl_floating_point * dstptr, unsigned int *status)
{
	register unsigned int opnd1, opnd2, opnd3, result;
	register int dest_exponent, count;
	register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE;
	boolean is_tiny;

	opnd1 = *srcptr1;
	opnd2 = *srcptr2;
	/* 
	 * set sign bit of result 
	 */
	if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) Sgl_setnegativezero(result);  
	else Sgl_setzero(result);
	/*
	 * check first operand for NaN's or infinity
	 */
	if (Sgl_isinfinity_exponent(opnd1)) {
		if (Sgl_iszero_mantissa(opnd1)) {
			if (Sgl_isnotnan(opnd2)) {
				if (Sgl_isinfinity(opnd2)) {
					/* 
					 * invalid since both operands 
					 * are infinity 
					 */
					if (Is_invalidtrap_enabled()) 
                                		return(INVALIDEXCEPTION);
                                	Set_invalidflag();
                                	Sgl_makequietnan(result);
					*dstptr = result;
					return(NOEXCEPTION);
				}
				/*
			 	 * return infinity
			 	 */
				Sgl_setinfinity_exponentmantissa(result);
				*dstptr = result;
				return(NOEXCEPTION);
			}
		}
		else {
                	/*
                 	 * is NaN; signaling or quiet?
                 	 */
                	if (Sgl_isone_signaling(opnd1)) {
                        	/* trap if INVALIDTRAP enabled */
                        	if (Is_invalidtrap_enabled()) 
                            		return(INVALIDEXCEPTION);
                        	/* make NaN quiet */
                        	Set_invalidflag();
                        	Sgl_set_quiet(opnd1);
                	}
			/* 
			 * is second operand a signaling NaN? 
			 */
			else if (Sgl_is_signalingnan(opnd2)) {
                        	/* trap if INVALIDTRAP enabled */
                        	if (Is_invalidtrap_enabled())
                            		return(INVALIDEXCEPTION);
                        	/* make NaN quiet */
                        	Set_invalidflag();
                        	Sgl_set_quiet(opnd2);
                		*dstptr = opnd2;
                		return(NOEXCEPTION);
			}
                	/*
                 	 * return quiet NaN
                 	 */
                	*dstptr = opnd1;
                	return(NOEXCEPTION);
		}
	}
	/*
	 * check second operand for NaN's or infinity
	 */
	if (Sgl_isinfinity_exponent(opnd2)) {
		if (Sgl_iszero_mantissa(opnd2)) {
			/*
			 * return zero
			 */
			Sgl_setzero_exponentmantissa(result);
			*dstptr = result;
			return(NOEXCEPTION);
		}
                /*
                 * is NaN; signaling or quiet?
                 */
                if (Sgl_isone_signaling(opnd2)) {
                        /* trap if INVALIDTRAP enabled */
                        if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                        /* make NaN quiet */
                        Set_invalidflag();
                        Sgl_set_quiet(opnd2);
                }
                /*
                 * return quiet NaN
                 */
                *dstptr = opnd2;
                return(NOEXCEPTION);
	}
	/*
	 * check for division by zero
	 */
	if (Sgl_iszero_exponentmantissa(opnd2)) {
		if (Sgl_iszero_exponentmantissa(opnd1)) {
			/* invalid since both operands are zero */
			if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                        Set_invalidflag();
                        Sgl_makequietnan(result);
			*dstptr = result;
			return(NOEXCEPTION);
		}
		if (Is_divisionbyzerotrap_enabled())
                        return(DIVISIONBYZEROEXCEPTION);
                Set_divisionbyzeroflag();
                Sgl_setinfinity_exponentmantissa(result);
		*dstptr = result;
		return(NOEXCEPTION);
	}
	/*
	 * Generate exponent 
	 */
	dest_exponent = Sgl_exponent(opnd1) - Sgl_exponent(opnd2) + SGL_BIAS;

	/*
	 * Generate mantissa
	 */
	if (Sgl_isnotzero_exponent(opnd1)) {
		/* set hidden bit */
		Sgl_clear_signexponent_set_hidden(opnd1);
	}
	else {
		/* check for zero */
		if (Sgl_iszero_mantissa(opnd1)) {
			Sgl_setzero_exponentmantissa(result);
			*dstptr = result;
			return(NOEXCEPTION);
		}
                /* is denormalized; want to normalize */
                Sgl_clear_signexponent(opnd1);
                Sgl_leftshiftby1(opnd1);
		Sgl_normalize(opnd1,dest_exponent);
	}
	/* opnd2 needs to have hidden bit set with msb in hidden bit */
	if (Sgl_isnotzero_exponent(opnd2)) {
		Sgl_clear_signexponent_set_hidden(opnd2);
	}
	else {
                /* is denormalized; want to normalize */
                Sgl_clear_signexponent(opnd2);
                Sgl_leftshiftby1(opnd2);
		while(Sgl_iszero_hiddenhigh7mantissa(opnd2)) {
			Sgl_leftshiftby8(opnd2);
			dest_exponent += 8;
		}
		if(Sgl_iszero_hiddenhigh3mantissa(opnd2)) {
			Sgl_leftshiftby4(opnd2);
			dest_exponent += 4;
		}
		while(Sgl_iszero_hidden(opnd2)) {
			Sgl_leftshiftby1(opnd2);
			dest_exponent += 1;
		}
	}

	/* Divide the source mantissas */

	/*
	 * A non_restoring divide algorithm is used.
	 */
	Sgl_subtract(opnd1,opnd2,opnd1);
	Sgl_setzero(opnd3);
	for (count=1;count<=SGL_P && Sgl_all(opnd1);count++) {
		Sgl_leftshiftby1(opnd1);
		Sgl_leftshiftby1(opnd3);
		if (Sgl_iszero_sign(opnd1)) {
			Sgl_setone_lowmantissa(opnd3);
			Sgl_subtract(opnd1,opnd2,opnd1);
		}
		else Sgl_addition(opnd1,opnd2,opnd1);
	}
	if (count <= SGL_P) {
		Sgl_leftshiftby1(opnd3);
		Sgl_setone_lowmantissa(opnd3);
		Sgl_leftshift(opnd3,SGL_P-count);
		if (Sgl_iszero_hidden(opnd3)) {
			Sgl_leftshiftby1(opnd3);
			dest_exponent--;
		}
	}
	else {
		if (Sgl_iszero_hidden(opnd3)) {
			/* need to get one more bit of result */
			Sgl_leftshiftby1(opnd1);
			Sgl_leftshiftby1(opnd3);
			if (Sgl_iszero_sign(opnd1)) {
				Sgl_setone_lowmantissa(opnd3);
				Sgl_subtract(opnd1,opnd2,opnd1);
			}
			else Sgl_addition(opnd1,opnd2,opnd1);
			dest_exponent--;
		}
		if (Sgl_iszero_sign(opnd1)) guardbit = TRUE;
		stickybit = Sgl_all(opnd1);
	}
	inexact = guardbit | stickybit;

	/* 
	 * round result 
	 */
	if (inexact && (dest_exponent > 0 || Is_underflowtrap_enabled())) {
		Sgl_clear_signexponent(opnd3);
		switch (Rounding_mode()) {
			case ROUNDPLUS: 
				if (Sgl_iszero_sign(result)) 
					Sgl_increment_mantissa(opnd3);
				break;
			case ROUNDMINUS: 
				if (Sgl_isone_sign(result)) 
					Sgl_increment_mantissa(opnd3);
				break;
			case ROUNDNEAREST:
				if (guardbit) {
			   	if (stickybit || Sgl_isone_lowmantissa(opnd3))
			      	    Sgl_increment_mantissa(opnd3);
				}
		}
		if (Sgl_isone_hidden(opnd3)) dest_exponent++;
	}
	Sgl_set_mantissa(result,opnd3);

        /* 
         * Test for overflow
         */
	if (dest_exponent >= SGL_INFINITY_EXPONENT) {
                /* trap if OVERFLOWTRAP enabled */
                if (Is_overflowtrap_enabled()) {
                        /*
                         * Adjust bias of result
                         */
                        Sgl_setwrapped_exponent(result,dest_exponent,ovfl);
                        *dstptr = result;
                        if (inexact) 
                            if (Is_inexacttrap_enabled())
                                return(OVERFLOWEXCEPTION | INEXACTEXCEPTION);
                            else Set_inexactflag();
                        return(OVERFLOWEXCEPTION);
                }
		Set_overflowflag();
                /* set result to infinity or largest number */
		Sgl_setoverflow(result);
		inexact = TRUE;
	}
        /* 
         * Test for underflow
         */
	else if (dest_exponent <= 0) {
                /* trap if UNDERFLOWTRAP enabled */
                if (Is_underflowtrap_enabled()) {
                        /*
                         * Adjust bias of result
                         */
                        Sgl_setwrapped_exponent(result,dest_exponent,unfl);
                        *dstptr = result;
                        if (inexact) 
                            if (Is_inexacttrap_enabled())
                                return(UNDERFLOWEXCEPTION | INEXACTEXCEPTION);
                            else Set_inexactflag();
                        return(UNDERFLOWEXCEPTION);
                }

		/* Determine if should set underflow flag */
		is_tiny = TRUE;
		if (dest_exponent == 0 && inexact) {
			switch (Rounding_mode()) {
			case ROUNDPLUS: 
				if (Sgl_iszero_sign(result)) {
					Sgl_increment(opnd3);
					if (Sgl_isone_hiddenoverflow(opnd3))
                			    is_tiny = FALSE;
					Sgl_decrement(opnd3);
				}
				break;
			case ROUNDMINUS: 
				if (Sgl_isone_sign(result)) {
					Sgl_increment(opnd3);
					if (Sgl_isone_hiddenoverflow(opnd3))
                			    is_tiny = FALSE;
					Sgl_decrement(opnd3);
				}
				break;
			case ROUNDNEAREST:
				if (guardbit && (stickybit || 
				    Sgl_isone_lowmantissa(opnd3))) {
				      	Sgl_increment(opnd3);
					if (Sgl_isone_hiddenoverflow(opnd3))
                			    is_tiny = FALSE;
					Sgl_decrement(opnd3);
				}
				break;
			}
		}

                /*
                 * denormalize result or set to signed zero
                 */
		stickybit = inexact;
		Sgl_denormalize(opnd3,dest_exponent,guardbit,stickybit,inexact);

		/* return rounded number */ 
		if (inexact) {
			switch (Rounding_mode()) {
			case ROUNDPLUS:
				if (Sgl_iszero_sign(result)) {
					Sgl_increment(opnd3);
				}
				break;
			case ROUNDMINUS: 
				if (Sgl_isone_sign(result))  {
					Sgl_increment(opnd3);
				}
				break;
			case ROUNDNEAREST:
				if (guardbit && (stickybit || 
				    Sgl_isone_lowmantissa(opnd3))) {
			      		Sgl_increment(opnd3);
				}
				break;
			}
                	if (is_tiny) Set_underflowflag();
                }
		Sgl_set_exponentmantissa(result,opnd3);
	}
	else Sgl_set_exponent(result,dest_exponent);
	*dstptr = result;
	/* check for inexact */
	if (inexact) {
		if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
		else  Set_inexactflag();
	}
	return(NOEXCEPTION);
}
示例#6
0
int
sgl_fsub(
	    sgl_floating_point *leftptr,
	    sgl_floating_point *rightptr,
	    sgl_floating_point *dstptr,
	    unsigned int *status)
    {
    register unsigned int left, right, result, extent;
    register unsigned int signless_upper_left, signless_upper_right, save;
    
    register int result_exponent, right_exponent, diff_exponent;
    register int sign_save, jumpsize;
    register boolean inexact = FALSE, underflowtrap;
        
    
    left = *leftptr;
    right = *rightptr;

    Sgl_xortointp1(left,right,save);

    if ((result_exponent = Sgl_exponent(left)) == SGL_INFINITY_EXPONENT)
	{
	if (Sgl_iszero_mantissa(left)) 
	    {
	    if (Sgl_isnotnan(right)) 
		{
		if (Sgl_isinfinity(right) && save==0) 
		    {
		    if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                    Set_invalidflag();
                    Sgl_makequietnan(result);
		    *dstptr = result;
		    return(NOEXCEPTION);
		    }
		*dstptr = left;
		return(NOEXCEPTION);
		}
	    }
	else 
	    {
            if (Sgl_isone_signaling(left)) 
		{
               	
		if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
        	
        	Set_invalidflag();
        	Sgl_set_quiet(left);
        	}
	    else if (Sgl_is_signalingnan(right)) 
		{
        	
               	if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
		
		Set_invalidflag();
		Sgl_set_quiet(right);
		*dstptr = right;
		return(NOEXCEPTION);
		}
 	    *dstptr = left;
 	    return(NOEXCEPTION);
	    }
	} 
    if (Sgl_isinfinity_exponent(right)) 
	{
	if (Sgl_iszero_mantissa(right)) 
	    {
	    
	    Sgl_invert_sign(right);
	    *dstptr = right;
	    return(NOEXCEPTION);
	    }
        if (Sgl_isone_signaling(right)) 
	    {
            
	    if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
	    
	    Set_invalidflag();
	    Sgl_set_quiet(right);
	    }
	*dstptr = right;
	return(NOEXCEPTION);
    	} 

    

    
    Sgl_copytoint_exponentmantissa(left,signless_upper_left);
    Sgl_copytoint_exponentmantissa(right,signless_upper_right);

    
    if(Sgl_ismagnitudeless(signless_upper_left,signless_upper_right))
	{
	Sgl_xorfromintp1(save,right,right);
	Sgl_xorfromintp1(save,left,left);
	result_exponent = Sgl_exponent(left);
	Sgl_invert_sign(left);
	}
     

    if((right_exponent = Sgl_exponent(right)) == 0)
        {
	
	if(Sgl_iszero_mantissa(right)) 
	    {
	    
	    if(Sgl_iszero_exponentmantissa(left))
		{
		
		Sgl_invert_sign(right);
		if(Is_rounding_mode(ROUNDMINUS))
		    {
		    Sgl_or_signs(left,right);
		    }
		else
		    {
		    Sgl_and_signs(left,right);
		    }
		}
	    else 
		{
		if( (result_exponent == 0) && Is_underflowtrap_enabled() )
		    {
		    
	    	    sign_save = Sgl_signextendedsign(left);
		    Sgl_leftshiftby1(left);
		    Sgl_normalize(left,result_exponent);
		    Sgl_set_sign(left,sign_save);
                    Sgl_setwrapped_exponent(left,result_exponent,unfl);
		    *dstptr = left;
		    
		    return(UNDERFLOWEXCEPTION);
		    }
		}
	    *dstptr = left;
	    return(NOEXCEPTION);
	    }

	
	Sgl_clear_sign(right);	
	if(result_exponent == 0 )
	    {
	    if( (int) save >= 0 )
		{
		Sgl_subtract(left,right,result);
		if(Sgl_iszero_mantissa(result))
		    {
		    if(Is_rounding_mode(ROUNDMINUS))
			{
			Sgl_setone_sign(result);
			}
		    else
			{
			Sgl_setzero_sign(result);
			}
		    *dstptr = result;
		    return(NOEXCEPTION);
		    }
		}
	    else
		{
		Sgl_addition(left,right,result);
		if(Sgl_isone_hidden(result))
		    {
		    *dstptr = result;
		    return(NOEXCEPTION);
		    }
		}
	    if(Is_underflowtrap_enabled())
		{
		
	    	sign_save = Sgl_signextendedsign(result);
		Sgl_leftshiftby1(result);
		Sgl_normalize(result,result_exponent);
		Sgl_set_sign(result,sign_save);
                Sgl_setwrapped_exponent(result,result_exponent,unfl);
		*dstptr = result;
		
		return(UNDERFLOWEXCEPTION);
		}
	    *dstptr = result;
	    return(NOEXCEPTION);
	    }
	right_exponent = 1;	
	}
    else
	{
	Sgl_clear_signexponent_set_hidden(right);
	}
    Sgl_clear_exponent_set_hidden(left);
    diff_exponent = result_exponent - right_exponent;

    if(diff_exponent > SGL_THRESHOLD)
	{
	diff_exponent = SGL_THRESHOLD;
	}
    
    
    Sgl_right_align(right,diff_exponent,
      extent);

    
    if( (int) save >= 0 )
	{
	Sgl_subtract_withextension(left,right,extent,result);
	if(Sgl_iszero_hidden(result))
	    {
	    
	    sign_save = Sgl_signextendedsign(result);
            Sgl_leftshiftby1_withextent(result,extent,result);

    	    if(Sgl_iszero(result))
		
		{
		if(Is_rounding_mode(ROUNDMINUS)) Sgl_setone_sign(result);
		*dstptr = result;
		return(NOEXCEPTION);
		}
	    result_exponent--;
	    
	    if(Sgl_isone_hidden(result))
		{
		if(result_exponent==0)
		    {
		    goto underflow;
		    }
		else
		    {
		    
		    Sgl_set_sign(result,sign_save);
	    	    Ext_leftshiftby1(extent);
		    goto round;
		    }
		}

	    if(!(underflowtrap = Is_underflowtrap_enabled()) &&
	       result_exponent==0) goto underflow;

	    Ext_leftshiftby1(extent);

	    
	    while(Sgl_iszero_hiddenhigh7mantissa(result))
		{
		Sgl_leftshiftby8(result);
		if((result_exponent -= 8) <= 0  && !underflowtrap)
		    goto underflow;
		}
	    
	    if(Sgl_iszero_hiddenhigh3mantissa(result))
		{
		
		Sgl_leftshiftby4(result);
		if((result_exponent -= 4) <= 0 && !underflowtrap)
		    goto underflow;
		}
	    if((jumpsize = Sgl_hiddenhigh3mantissa(result)) > 7)
		{
		
		if(result_exponent <= 0) goto underflow;
		Sgl_set_sign(result,sign_save);
		Sgl_set_exponent(result,result_exponent);
		*dstptr = result;
		return(NOEXCEPTION);
		}
	    Sgl_sethigh4bits(result,sign_save);
	    switch(jumpsize) 
		{
		case 1:
		    {
		    Sgl_leftshiftby3(result);
		    result_exponent -= 3;
		    break;
		    }
		case 2:
		case 3:
		    {
		    Sgl_leftshiftby2(result);
		    result_exponent -= 2;
		    break;
		    }
		case 4:
		case 5:
		case 6:
		case 7:
		    {
		    Sgl_leftshiftby1(result);
		    result_exponent -= 1;
		    break;
		    }
		}
	    if(result_exponent > 0) 
		{
		Sgl_set_exponent(result,result_exponent);
		*dstptr = result;	
		return(NOEXCEPTION);
		}
	    
	  underflow:
	    if(Is_underflowtrap_enabled())
		{
		Sgl_set_sign(result,sign_save);
                Sgl_setwrapped_exponent(result,result_exponent,unfl);
		*dstptr = result;
		
		return(UNDERFLOWEXCEPTION);
		}
	    Sgl_right_align(result,(1-result_exponent),extent);
	    Sgl_clear_signexponent(result);
	    Sgl_set_sign(result,sign_save);
	    *dstptr = result;
	    return(NOEXCEPTION);
	    } 
	
	} 
    else 
	{
	
	Sgl_addition(left,right,result);
	if(Sgl_isone_hiddenoverflow(result))
	    {
	    
	    Sgl_rightshiftby1_withextent(result,extent,extent);
	    Sgl_arithrightshiftby1(result);
	    result_exponent++;
	    } 
	} 
    
  round:
    if(Ext_isnotzero(extent))
	{
	inexact = TRUE;
	switch(Rounding_mode())
	    {
	    case ROUNDNEAREST: 
	    if(Ext_isone_sign(extent))
		{
		
		if(Ext_isnotzero_lower(extent)  ||
		  Sgl_isone_lowmantissa(result))
		    {
		    
		    Sgl_increment(result);
		    }
		}
	    break;

	    case ROUNDPLUS:
	    if(Sgl_iszero_sign(result))
		{
		
		Sgl_increment(result);
		}
	    break;
	    
	    case ROUNDMINUS:
	    if(Sgl_isone_sign(result))
		{
		
		Sgl_increment(result);
		}
	    
	    case ROUNDZERO:;
	    
	    } 
	if(Sgl_isone_hiddenoverflow(result)) result_exponent++;
	}
    if(result_exponent == SGL_INFINITY_EXPONENT)
        {
        
        if(Is_overflowtrap_enabled())
	    {
	    Sgl_setwrapped_exponent(result,result_exponent,ovfl);
	    *dstptr = result;
	    if (inexact)
		if (Is_inexacttrap_enabled())
		    return(OVERFLOWEXCEPTION | INEXACTEXCEPTION);
		else Set_inexactflag();
	    return(OVERFLOWEXCEPTION);
	    }
        else
	    {
	    Set_overflowflag();
	    inexact = TRUE;
	    Sgl_setoverflow(result);
	    }
	}
    else Sgl_set_exponent(result,result_exponent);
    *dstptr = result;
    if(inexact) 
	if(Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
	else Set_inexactflag();
    return(NOEXCEPTION);
    }