fixed: Big::FromDouble(double) sometimes sets a wrong value
there was SetSign() used when the value was not
defined, and also was a small mistake when the mantissa
was equal one word (on 32bit platforms)
added: uint Big::ToDouble(double&) - converting into double
git-svn-id: svn://ttmath.org/publicrep/ttmath/trunk@49 e52654a7-88a9-db11-a3e9-0013d4bc506e
This commit is contained in:
parent
692ff5406e
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25f876762a
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@ -1725,18 +1725,14 @@ public:
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union
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{
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double d;
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unsigned int u[2]; // two 32bit words
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uint u[2]; // two 32bit words
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} temp;
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temp.d = value;
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info = 0;
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if( temp.u[1] & 0x80000000u )
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SetSign();
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int e = (temp.u[1] & 0x7FF00000u) >> 20;
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unsigned int m1 = ((temp.u[1] & 0xFFFFFu) << 11) | (temp.u[0] >> 21);
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unsigned int m2 = temp.u[0] << 11;
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sint e = ( temp.u[1] & 0x7FF00000u) >> 20;
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uint m1 = ((temp.u[1] & 0xFFFFFu) << 11) | (temp.u[0] >> 21);
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uint m2 = temp.u[0] << 11;
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if( e == 2047 )
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{
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@ -1756,7 +1752,9 @@ public:
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// where "1.F" is intended to represent the binary number
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// created by prefixing F with an implicit leading 1 and a binary point.
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FromDouble_SetExpAndMan(e - 1023 - man*TTMATH_BITS_PER_UINT + 1, 0x80000000u, m1, m2);
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FromDouble_SetExpAndMan(bool(temp.u[1] & 0x80000000u),
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e - 1023 - man*TTMATH_BITS_PER_UINT + 1, 0x80000000u,
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m1, m2);
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// we do not have to call Standardizing() here
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// because the mantissa will have the highest bit set
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@ -1771,8 +1769,14 @@ public:
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// then V=(-1)**S * 2 ** (-1022) * (0.F)
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// These are "unnormalized" values.
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FromDouble_SetExpAndMan(e - 1022 - man*TTMATH_BITS_PER_UINT + 1, 0, m1, m2);
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Standardizing();
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UInt<2> m;
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m.table[1] = m1;
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m.table[0] = m2;
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uint moved = m.CompensationToLeft();
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FromDouble_SetExpAndMan(bool(temp.u[1] & 0x80000000u),
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e - 1022 - man*TTMATH_BITS_PER_UINT + 1 - moved, 0,
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m.table[1], m.table[2]);
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}
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else
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{
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@ -1788,23 +1792,29 @@ public:
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private:
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void FromDouble_SetExpAndMan(int e, unsigned int mhighest,
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unsigned int m1, unsigned int m2)
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void FromDouble_SetExpAndMan(bool is_sign, int e, uint mhighest, uint m1, uint m2)
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{
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exponent = e;
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if( man > 1 )
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{
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mantissa.table[man-1] = m1 | mhighest;
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mantissa.table[man-2] = m2;
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mantissa.table[sint(man-2)] = m2;
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// although man>1 we're using casting into sint
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// to get rid from a warning which generates Microsoft Visual:
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// warning C4307: '*' : integral constant overflow
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for(unsigned int i=0 ; i<man-2 ; ++i)
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for(uint i=0 ; i<man-2 ; ++i)
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mantissa.table[i] = 0;
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}
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else
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{
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mantissa.table[0] = m1 | mhighest;
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}
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info = 0;
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if( is_sign )
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SetSign();
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}
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@ -1829,13 +1839,9 @@ public:
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} temp;
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temp.d = value;
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info = 0;
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if( temp.u & 0x8000000000000000ul )
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SetSign();
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int e = (temp.u & 0x7FF0000000000000ul) >> 52;
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uint m = (temp.u & 0xFFFFFFFFFFFFFul) << 11;
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sint e = (temp.u & 0x7FF0000000000000ul) >> 52;
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uint m = (temp.u & 0xFFFFFFFFFFFFFul) << 11;
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if( e == 2047 )
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{
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@ -1855,7 +1861,9 @@ public:
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// where "1.F" is intended to represent the binary number
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// created by prefixing F with an implicit leading 1 and a binary point.
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FromDouble_SetExpAndMan(e - 1023 - man*TTMATH_BITS_PER_UINT + 1, 0x8000000000000000ul, m);
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FromDouble_SetExpAndMan(bool(temp.u & 0x8000000000000000ul),
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e - 1023 - man*TTMATH_BITS_PER_UINT + 1,
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0x8000000000000000ul, m);
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// we do not have to call Standardizing() here
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// because the mantissa will have the highest bit set
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@ -1870,7 +1878,8 @@ public:
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// then V=(-1)**S * 2 ** (-1022) * (0.F)
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// These are "unnormalized" values.
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FromDouble_SetExpAndMan(e - 1022 - man*TTMATH_BITS_PER_UINT + 1, 0, m);
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FromDouble_SetExpAndMan(bool(temp.u & 0x8000000000000000ul),
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e - 1022 - man*TTMATH_BITS_PER_UINT + 1, 0, m);
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Standardizing();
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}
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else
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@ -1886,13 +1895,17 @@ public:
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private:
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void FromDouble_SetExpAndMan(int e, uint mhighest, uint m)
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void FromDouble_SetExpAndMan(bool is_sign, sint e, uint mhighest, uint m)
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{
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exponent = e;
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mantissa.table[man-1] = m | mhighest;
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for(unsigned int i=0 ; i<man-1 ; ++i)
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for(uint i=0 ; i<man-1 ; ++i)
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mantissa.table[i] = 0;
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info = 0;
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if( is_sign )
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SetSign();
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}
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#endif
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@ -1900,6 +1913,140 @@ private:
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public:
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/*!
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this method converts from this class into the 'double'
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if the value is too big:
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'result' will be +/-infinity (depending on the sign)
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and the method returns 1
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if the value is too small:
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'result' will be 0
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and the method returns 1
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*/
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uint ToDouble(double & result) const
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{
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// sizeof(double) should be 8 (64 bits), this is actually not a runtime
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// error but I leave it at the moment as is
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TTMATH_ASSERT( sizeof(double) == 8 )
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if( IsZero() )
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{
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result = 0.0;
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return 0;
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}
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sint e_correction = sint(man*TTMATH_BITS_PER_UINT) - 1;
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if( exponent >= 1024 - e_correction )
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{
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// +/- infinity
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result = ToDouble_SetDouble( IsSign(), 2047, 0, true);
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return 1;
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}
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else
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if( exponent <= -1023 - 52 - e_correction )
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{
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// too small value - we assume that there'll be a zero
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result = 0;
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// and return a carry
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return 1;
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}
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sint e = exponent.ToInt() + e_correction;
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if( e <= -1023 )
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{
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// -1023-52 < e <= -1023 (unnormalized value)
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result = ToDouble_SetDouble( IsSign(), 0, -(e + 1023));
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}
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else
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{
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// -1023 < e < 1024
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result = ToDouble_SetDouble( IsSign(), e + 1023, -1);
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}
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return 0;
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}
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private:
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#ifdef TTMATH_PLATFORM32
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// 32bit platforms
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double ToDouble_SetDouble(bool is_sign, uint e, sint move, bool infinity = false) const
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{
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union
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{
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double d;
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uint u[2]; // two 32bit words
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} temp;
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temp.u[0] = temp.u[1] = 0;
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if( is_sign )
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temp.u[1] |= 0x80000000u;
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temp.u[1] |= (e << 20) & 0x7FF00000u;
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if( infinity )
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return temp.d;
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UInt<2> m;
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m.table[1] = mantissa.table[man-1];
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m.table[0] = ( man > 1 ) ? mantissa.table[sint(man-2)] : 0;
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// although man>1 we're using casting into sint
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// to get rid from a warning which generates Microsoft Visual:
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// warning C4307: '*' : integral constant overflow
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m.Rcr( 12 + move );
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m.table[1] &= 0xFFFFFu; // cutting the 20 bit (when 'move' was -1)
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temp.u[1] |= m.table[1];
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temp.u[0] |= m.table[0];
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return temp.d;
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}
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#else
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// 64bit platforms
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double ToDouble_SetDouble(bool is_sign, uint e, sint move, bool infinity = false) const
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{
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union
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{
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double d;
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uint u; // 64bit word
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} temp;
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temp.u = 0;
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if( is_sign )
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temp.u |= 0x8000000000000000ul;
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temp.u |= (e << 52) & 0x7FF0000000000000ul;
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if( infinity )
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return temp.d;
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uint m = mantissa.table[man-1];
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m >>= ( 12 + move );
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m &= 0xFFFFFFFFFFFFFul; // cutting the 20 bit (when 'move' was -1)
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temp.u |= m;
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return temp.d;
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}
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#endif
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public:
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/*!
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an operator= for converting 'sint' to this class
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*/
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