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68 lines
1.7 KiB
68 lines
1.7 KiB
// cl_DF_to_FF().
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// General includes.
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#include "cl_sysdep.h"
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// Specification.
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#include "cl_F.h"
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// Implementation.
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#include "cl_DF.h"
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#include "cl_FF.h"
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namespace cln {
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const cl_FF cl_DF_to_FF (const cl_DF& x)
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{
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// x entpacken:
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var cl_signean sign;
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var sintL exp;
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#if (cl_word_size==64)
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var uint64 mant;
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DF_decode(x, { return cl_FF_0; }, sign=,exp=,mant=);
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// 52-23=29 Bits wegrunden:
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var const int shiftcount = DF_mant_len-FF_mant_len;
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if ( ((mant & bit(shiftcount-1)) ==0) // Bit 28 war 0 -> abrunden
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|| ( ((mant & (bit(shiftcount-1)-1)) ==0) // war 1, Bits 27..0 >0 -> aufrunden
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// round-to-even
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&& ((mant & bit(shiftcount)) ==0)
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) )
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// abrunden
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{ mant = mant >> shiftcount; }
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else
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// aufrunden
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{ mant = mant >> shiftcount;
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mant = mant+1;
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if (mant >= bit(FF_mant_len+1))
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// Überlauf durchs Runden
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{ mant = mant>>1; exp = exp+1; } // Mantisse rechts schieben
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}
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return encode_FF(sign,exp,mant);
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#else
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var uint32 manthi;
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var uint32 mantlo;
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DF_decode2(x, { return cl_FF_0; }, sign=,exp=,manthi=,mantlo=);
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// 52-23=29 Bits wegrunden:
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var const int shiftcount = DF_mant_len-FF_mant_len;
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manthi = (manthi << (32-shiftcount)) | (mantlo >> shiftcount);
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if ( ((mantlo & bit(shiftcount-1)) ==0) // Bit 28 war 0 -> abrunden
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|| ( ((mantlo & (bit(shiftcount-1)-1)) ==0) // war 1, Bits 27..0 >0 -> aufrunden
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// round-to-even
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&& ((mantlo & bit(shiftcount)) ==0)
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) )
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// abrunden
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{}
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else
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// aufrunden
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{ manthi = manthi+1;
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if (manthi >= bit(FF_mant_len+1))
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// Überlauf durchs Runden
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{ manthi = manthi>>1; exp = exp+1; } // Mantisse rechts schieben
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}
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return encode_FF(sign,exp,manthi);
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#endif
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}
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} // namespace cln
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