fnd/format/FndIEEE80.h

//======================================================================
//-----------------------------------------------------------------------
/**
 * @file                FndIEEE80.h
 * @brief               IEEE754 80bit ファイル
 *
 * @author              t.sirayanagi
 * @version             1.0
 *
 * @par                 copyright
 * Copyright (C) 2011-2012 Takazumi Shirayanagi\n
 * The new BSD License is applied to this software.
 * see iris_LICENSE.txt
*/
//-----------------------------------------------------------------------
//======================================================================
#ifndef INCG_IRIS_FndIEEE80_H_
#define INCG_IRIS_FndIEEE80_H_

//======================================================================
// include
#include "FndIEEE.h"

namespace iris {
namespace fnd
{

//======================================================================
// class
/**
 * @brief       IEEE754 80bit クラス
 * @note        符号bit : 1
 *                      仮数bit : 64
 *                      指数bit : 15
*/
class CIEEEBinary80 : public IIrisObject
{
protected:
        u8      m_buf[10];      //!< バッファ(BIGENDIAN で格納)
public:
        // コンストラクタ
        CIEEEBinary80(void) {}
public:
        // メモリコピー
        void    CopyBufferBE(const u8* buf)
        {
                for( int i=0; i < elementof(m_buf); ++i, ++buf ) m_buf[i] = *buf;
        }
        void    CopyBufferLE(const u8* buf)
        {
                for( int i=0; i < elementof(m_buf); ++i, ++buf ) m_buf[9-i] = *buf;
        }

public:
        operator float  (void)  const   { return cast_to_float(); }
        operator double (void)  const   { return cast_to_double(); }

public:
        u8*                     GetBuffer(void)                 { return m_buf; }
        const u8*       GetBuffer(void) const   { return m_buf; }

public:
        // 符号部
        u32             sign(void) const                { return (m_buf[0]>>7) & 1; }
        // 指数部
        u32             exp(void) const                 { return (static_cast<u32>(m_buf[0]&0x7F) << 8) | (static_cast<u32>(m_buf[1]) << 0); }
        // 仮数部
        u64             frac(void) const
        {
                return (static_cast<u64>(m_buf[2]) << 56) | (static_cast<u64>(m_buf[3]) << 48) | (static_cast<u64>(m_buf[4]) << 40)
                        |  (static_cast<u64>(m_buf[5]) << 32) | (static_cast<u64>(m_buf[6]) << 24) | (static_cast<u64>(m_buf[7]) << 16)
                        |  (static_cast<u64>(m_buf[8]) <<  8) | (static_cast<u64>(m_buf[9]));
        }
private:
        float cast_to_float(void) const
        {
                CIEEEBinary32 ieee;
                u32 exp_ = exp();
                if( exp_ == (1<<15)-1 )
                {
                        exp_ = (1<<8)-1;
                }
                else if( exp_ != 0 )
                {
                        exp_ -= (1<<14)-1;
                        exp_ += (1<<7)-1;
                        if( exp_ & ~0xFF )
                        {
                                // INF
                                ieee.value() = 0x7F800000;
                                ieee.sign(sign());
                                return ieee;
                        }
                }
                ieee.sign(sign());
                ieee.exp(exp_);
                ieee.frac((frac()>>40)&0x7FFFFF);       // 暗黙の1bitを捨てる
                return ieee;
        }
        double cast_to_double(void) const
        {
                CIEEEBinary64 ieee;
                u32 exp_ = exp();
                if( exp_ == (1<<15)-1 )
                {
                        exp_ = (1<<11)-1;
                }
                else if( exp_ != 0 )
                {
                        exp_ -= (1<<14)-1;
                        exp_ += (1<<10)-1;
                        if( exp_ & ~0x7FF )
                        {
                                // INF
                                ieee.value() = 0x7FF0000000000000;
                                ieee.sign(sign());
                                return ieee;
                        }
                }
                ieee.sign(sign());
                ieee.exp(exp_);
                ieee.frac((frac()>>11)&0xFFFFFFFFFFFFF);        // 暗黙の1bitを捨てる
                return ieee;
        }
};

}       // end of namespace fnd
}       // end of namespace iris

#endif