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647 cejka 1
/*
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 * Copyright (C) 2005 Josef Cejka
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include "sftypes.h"
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#include "conversion.h"
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#include "comparison.h"
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float64 convertFloat32ToFloat64(float32 a)
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{
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    float64 result;
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    __u64 frac;
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    result.parts.sign = a.parts.sign;
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    result.parts.fraction = a.parts.fraction;
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    result.parts.fraction <<= (FLOAT64_FRACTION_SIZE - FLOAT32_FRACTION_SIZE );
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    if ((isFloat32Infinity(a))||(isFloat32NaN(a))) {
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        result.parts.exp = 0x7FF;
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        /* TODO; check if its correct for SigNaNs*/
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        return result;
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    };
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    result.parts.exp = a.parts.exp + ( (int)FLOAT64_BIAS - FLOAT32_BIAS );
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    if (a.parts.exp == 0) {
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        /* normalize denormalized numbers */
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        if (result.parts.fraction == 0ll) { /* fix zero */
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            result.parts.exp = 0ll;
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            return result;
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        }
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        frac = result.parts.fraction;
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        while (!(frac & (0x10000000000000ll))) {
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            frac <<= 1;
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            --result.parts.exp;
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        };
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        ++result.parts.exp;
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        result.parts.fraction = frac;
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    };
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    return result;
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}
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float32 convertFloat64ToFloat32(float64 a)
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{
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    float32 result;
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    __s32 exp;
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    __u64 frac;
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    result.parts.sign = a.parts.sign;
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    if (isFloat64NaN(a)) {
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        result.parts.exp = 0xFF;
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        if (isFloat64SigNaN(a)) {
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            result.parts.fraction = 0x800000; /* set first bit of fraction nonzero */
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            return result;
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        }
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        result.parts.fraction = 0x1; /* fraction nonzero but its first bit is zero */
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        return result;
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    };
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    if (isFloat64Infinity(a)) {
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        result.parts.fraction = 0;
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        result.parts.exp = 0xFF;
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        return result;
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    };
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    exp = (int)a.parts.exp - FLOAT64_BIAS + FLOAT32_BIAS;
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    if (exp >= 0xFF) {
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        /*FIXME: overflow*/
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        result.parts.fraction = 0;
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        result.parts.exp = 0xFF;
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        return result;
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    } else if (exp <= 0 ) {
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        /* underflow or denormalized */
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        result.parts.exp = 0;
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        exp *= -1; 
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        if (exp > FLOAT32_FRACTION_SIZE ) {
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            /* FIXME: underflow */
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            result.parts.fraction = 0;
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            return result;
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        };
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        /* denormalized */
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        frac = a.parts.fraction;
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        frac |= 0x10000000000000ll; /* denormalize and set hidden bit */
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        frac >>= (FLOAT64_FRACTION_SIZE - FLOAT32_FRACTION_SIZE + 1);
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        while (exp > 0) {
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            --exp;
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            frac >>= 1;
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        };
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        result.parts.fraction = frac;
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        return result;
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    };
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    result.parts.exp = exp;
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    result.parts.fraction = a.parts.fraction >> (FLOAT64_FRACTION_SIZE - FLOAT32_FRACTION_SIZE);
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    return result;
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}
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/** Helping procedure for converting float32 to uint32
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 * @param a floating point number in normalized form (no NaNs or Inf are checked )
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 * @return unsigned integer
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 */
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static __u32 _float32_to_uint32_helper(float32 a)
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{
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    __u32 frac;
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    if (a.parts.exp < FLOAT32_BIAS) {
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        /*TODO: rounding*/
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        return 0;
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    }
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    frac = a.parts.fraction;
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    frac |= FLOAT32_HIDDEN_BIT_MASK;
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    /* shift fraction to left so hidden bit will be the most significant bit */
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    frac <<= 32 - FLOAT32_FRACTION_SIZE - 1;
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    frac >>= 32 - (a.parts.exp - FLOAT32_BIAS) - 1;
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    if ((a.parts.sign == 1) && (frac != 0)) {
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        frac = ~frac;
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        ++frac;
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    }
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    return frac;
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}
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/* Convert float to unsigned int32
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 * FIXME: Im not sure what to return if overflow/underflow happens
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 *  - now its the biggest or the smallest int
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 */
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__u32 float32_to_uint32(float32 a)
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{
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    if (isFloat32NaN(a)) {
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        return MAX_UINT32;
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    }
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    if (isFloat32Infinity(a) || (a.parts.exp >= (32 + FLOAT32_BIAS)))  {
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        if (a.parts.sign) {
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            return MIN_UINT32;
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        }
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        return MAX_UINT32;
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    }
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187
    return _float32_to_uint32_helper(a);   
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}
189
 
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/* Convert float to signed int32
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 * FIXME: Im not sure what to return if overflow/underflow happens
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 *  - now its the biggest or the smallest int
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 */
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__s32 float32_to_int32(float32 a)
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{
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    if (isFloat32NaN(a)) {
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        return MAX_INT32;
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    }
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    if (isFloat32Infinity(a) || (a.parts.exp >= (32 + FLOAT32_BIAS)))  {
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        if (a.parts.sign) {
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            return MIN_INT32;
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        }
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        return MAX_INT32;
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    }
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    return _float32_to_uint32_helper(a);
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}  
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