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/*

 * Copyright (C) 2005 Josef Cejka

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include<sftypes.h>

#include<add.h>

#include<comparison.h>

/** Add two Float32 numbers with same signs

 */

float32 addFloat32(float32 a, float32 b)

{

	int expdiff;

	__u32 exp1, exp2,frac1, frac2;

	expdiff = a.parts.exp - b.parts.exp;

	if (expdiff < 0) {

		if (isFloat32NaN(b)) {

			/* TODO: fix SigNaN */

			if (isFloat32SigNaN(b)) {

			};

			return b;

		};

		if (b.parts.exp == FLOAT32_MAX_EXPONENT) { 

			return b;

		}

		frac1 = b.parts.fraction;

		exp1 = b.parts.exp;

		frac2 = a.parts.fraction;

		exp2 = a.parts.exp;

		expdiff *= -1;

	} else {

		if ((isFloat32NaN(a)) || (isFloat32NaN(b))) {

			/* TODO: fix SigNaN */

			if (isFloat32SigNaN(a) || isFloat32SigNaN(b)) {

			};

			return (isFloat32NaN(a)?a:b);

		};

		if (a.parts.exp == FLOAT32_MAX_EXPONENT) { 

			return a;

		}

		frac1 = a.parts.fraction;

		exp1 = a.parts.exp;

		frac2 = b.parts.fraction;

		exp2 = b.parts.exp;

	};

	if (exp1 == 0) {

		/* both are denormalized */

		frac1 += frac2;

		if (frac1 & FLOAT32_HIDDEN_BIT_MASK ) {

			/* result is not denormalized */

			a.parts.exp = 1;

		};

		a.parts.fraction = frac1;

		return a;

	};

	frac1 |= FLOAT32_HIDDEN_BIT_MASK; /* add hidden bit */

	if (exp2 == 0) {

		/* second operand is denormalized */

		--expdiff;

	} else {

		/* add hidden bit to second operand */

		frac2 |= FLOAT32_HIDDEN_BIT_MASK; 

	};

	/* create some space for rounding */

	frac1 <<= 6;

	frac2 <<= 6;

	if (expdiff < (FLOAT32_FRACTION_SIZE + 2) ) {

		frac2 >>= expdiff;

		frac1 += frac2;

		};

	if (frac1 & (FLOAT32_HIDDEN_BIT_MASK << 7) ) {

		++exp1;

		frac1 >>= 1;

	};

	/* rounding - if first bit after fraction is set then round up */

	frac1 += (0x1 << 5);

	if (frac1 & (FLOAT32_HIDDEN_BIT_MASK << 7)) { 

		/* rounding overflow */

		++exp1;

		frac1 >>= 1;

	};

	if ((exp1 == FLOAT32_MAX_EXPONENT ) || (exp2 > exp1)) {

			/* overflow - set infinity as result */

			a.parts.exp = FLOAT32_MAX_EXPONENT;

			a.parts.fraction = 0;

			return a;

			}

	a.parts.exp = exp1;

	/*Clear hidden bit and shift */

	a.parts.fraction = ((frac1 >> 6) & (~FLOAT32_HIDDEN_BIT_MASK)) ; 

	return a;

}

/** Add two Float64 numbers with same signs

 */

float64 addFloat64(float64 a, float64 b)

{

	int expdiff;

	__u32 exp1, exp2;

	__u64 frac1, frac2;

	expdiff = a.parts.exp - b.parts.exp;

	if (expdiff < 0) {

		if (isFloat64NaN(b)) {

			/* TODO: fix SigNaN */

			if (isFloat64SigNaN(b)) {

			};

			return b;

		};

		/* b is infinity and a not */	

		if (b.parts.exp == FLOAT64_MAX_EXPONENT ) { 

			return b;

		}

		frac1 = b.parts.fraction;

		exp1 = b.parts.exp;

		frac2 = a.parts.fraction;

		exp2 = a.parts.exp;

		expdiff *= -1;

	} else {

		if (isFloat64NaN(a)) {

			/* TODO: fix SigNaN */

			if (isFloat64SigNaN(a) || isFloat64SigNaN(b)) {

			};

			return a;

		};

		/* a is infinity and b not */

		if (a.parts.exp == FLOAT64_MAX_EXPONENT ) { 

			return a;

		}

		frac1 = a.parts.fraction;

		exp1 = a.parts.exp;

		frac2 = b.parts.fraction;

		exp2 = b.parts.exp;

	};

	if (exp1 == 0) {

		/* both are denormalized */

		frac1 += frac2;

		if (frac1 & FLOAT64_HIDDEN_BIT_MASK) { 

			/* result is not denormalized */

			a.parts.exp = 1;

		};

		a.parts.fraction = frac1;

		return a;

	};

	/* add hidden bit - frac1 is sure not denormalized */

	frac1 |= FLOAT64_HIDDEN_BIT_MASK;

	/* second operand ... */

	if (exp2 == 0) {

		/* ... is denormalized */

		--expdiff;	

	} else {

		/* is not denormalized */

		frac2 |= FLOAT64_HIDDEN_BIT_MASK;

	};

	/* create some space for rounding */

	frac1 <<= 6;

	frac2 <<= 6;

	if (expdiff < (FLOAT64_FRACTION_SIZE + 2) ) {

		frac2 >>= expdiff;

		frac1 += frac2;

		};

	if (frac1 & (FLOAT64_HIDDEN_BIT_MASK << 7) ) {

		++exp1;

		frac1 >>= 1;

	};

	/* rounding - if first bit after fraction is set then round up */

	frac1 += (0x1 << 5); 

	if (frac1 & (FLOAT64_HIDDEN_BIT_MASK << 7)) { 

		/* rounding overflow */

		++exp1;

		frac1 >>= 1;

	};

	if ((a.parts.exp == FLOAT64_MAX_EXPONENT ) || (a.parts.exp < exp1)) {

			/* overflow - set infinity as result */

			a.parts.exp = FLOAT64_MAX_EXPONENT;

			a.parts.fraction = 0;

			return a;

			}

	a.parts.exp = exp1;

	/*Clear hidden bit and shift */

	a.parts.fraction = ( (frac1 >> 6 ) & (~FLOAT64_HIDDEN_BIT_MASK));

	return a;

}