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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 "conversion.h"

#include "comparison.h"

float64 convertFloat32ToFloat64(float32 a)

{

    float64 result;

    __u64 frac;

    result.parts.sign = a.parts.sign;

    result.parts.fraction = a.parts.fraction;

    result.parts.fraction <<= (FLOAT64_FRACTION_SIZE - FLOAT32_FRACTION_SIZE );

    if ((isFloat32Infinity(a))||(isFloat32NaN(a))) {

        result.parts.exp = 0x7FF;

        /* TODO; check if its correct for SigNaNs*/

        return result;

    };

    result.parts.exp = a.parts.exp + ( (int)FLOAT64_BIAS - FLOAT32_BIAS );

    if (a.parts.exp == 0) {

        /* normalize denormalized numbers */

        if (result.parts.fraction == 0ll) { /* fix zero */

            result.parts.exp = 0ll;

            return result;

        }

        frac = result.parts.fraction;

        while (!(frac & (0x10000000000000ll))) {

            frac <<= 1;

            --result.parts.exp;

        };

        ++result.parts.exp;

        result.parts.fraction = frac;

    };

    return result;

}

float32 convertFloat64ToFloat32(float64 a)

{

    float32 result;

    __s32 exp;

    __u64 frac;

    result.parts.sign = a.parts.sign;

    if (isFloat64NaN(a)) {

        result.parts.exp = 0xFF;

        if (isFloat64SigNaN(a)) {

            result.parts.fraction = 0x800000; /* set first bit of fraction nonzero */

            return result;

        }

        result.parts.fraction = 0x1; /* fraction nonzero but its first bit is zero */

        return result;

    };

    if (isFloat64Infinity(a)) {

        result.parts.fraction = 0;

        result.parts.exp = 0xFF;

        return result;

    };

    exp = (int)a.parts.exp - FLOAT64_BIAS + FLOAT32_BIAS;

    if (exp >= 0xFF) {

        /*FIXME: overflow*/

        result.parts.fraction = 0;

        result.parts.exp = 0xFF;

        return result;

    } else if (exp <= 0 ) {

        /* underflow or denormalized */

        result.parts.exp = 0;

        exp *= -1; 

        if (exp > FLOAT32_FRACTION_SIZE ) {

            /* FIXME: underflow */

            result.parts.fraction = 0;

            return result;

        };

        /* denormalized */

        frac = a.parts.fraction;

        frac |= 0x10000000000000ll; /* denormalize and set hidden bit */

        frac >>= (FLOAT64_FRACTION_SIZE - FLOAT32_FRACTION_SIZE + 1);

        while (exp > 0) {

            --exp;

            frac >>= 1;

        };

        result.parts.fraction = frac;

        return result;

    };

    result.parts.exp = exp;

    result.parts.fraction = a.parts.fraction >> (FLOAT64_FRACTION_SIZE - FLOAT32_FRACTION_SIZE);

    return result;

}

/** Helping procedure for converting float32 to uint32

 * @param a floating point number in normalized form (no NaNs or Inf are checked )

 * @return unsigned integer

 */

static __u32 _float32_to_uint32_helper(float32 a)

{

    __u32 frac;

    if (a.parts.exp < FLOAT32_BIAS) {

        /*TODO: rounding*/

        return 0;

    }

    frac = a.parts.fraction;

    frac |= FLOAT32_HIDDEN_BIT_MASK;

    /* shift fraction to left so hidden bit will be the most significant bit */

    frac <<= 32 - FLOAT32_FRACTION_SIZE - 1;

    frac >>= 32 - (a.parts.exp - FLOAT32_BIAS) - 1;

    if ((a.parts.sign == 1) && (frac != 0)) {

        frac = ~frac;

        ++frac;

    }

    return frac;

}

/* Convert float to unsigned int32

 * FIXME: Im not sure what to return if overflow/underflow happens

 *  - now its the biggest or the smallest int

 */

__u32 float32_to_uint32(float32 a)

{

    if (isFloat32NaN(a)) {

        return MAX_UINT32;

    }

    if (isFloat32Infinity(a) || (a.parts.exp >= (32 + FLOAT32_BIAS)))  {

        if (a.parts.sign) {

            return MIN_UINT32;

        }

        return MAX_UINT32;

    }

    return _float32_to_uint32_helper(a);   

}

/* Convert float to signed int32

 * FIXME: Im not sure what to return if overflow/underflow happens

 *  - now its the biggest or the smallest int

 */

__s32 float32_to_int32(float32 a)

{

    if (isFloat32NaN(a)) {

        return MAX_INT32;

    }

    if (isFloat32Infinity(a) || (a.parts.exp >= (32 + FLOAT32_BIAS)))  {

        if (a.parts.sign) {

            return MIN_INT32;

        }

        return MAX_INT32;

    }

    return _float32_to_uint32_helper(a);

}