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97 lines
2.7 KiB
97 lines
2.7 KiB
// read_float().
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// General includes.
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#include "base/cl_sysdep.h"
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// Specification.
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#include "cln/float_io.h"
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// Implementation.
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#include "cln/integer.h"
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#include "integer/cl_I.h"
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#include "cln/rational.h"
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#include "rational/cl_RA.h"
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#include "cln/float.h"
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#include "cln/sfloat.h"
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#include "cln/ffloat.h"
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#include "cln/dfloat.h"
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#include "cln/lfloat.h"
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#include "float/cl_F.h"
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#include "float/sfloat/cl_SF.h"
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#include "float/ffloat/cl_FF.h"
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#include "float/dfloat/cl_DF.h"
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#include "float/lfloat/cl_LF.h"
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namespace cln {
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const cl_F read_float (unsigned int base, float_format_t prec, cl_signean sign, const char * string, uintC index1, uintC index4, uintC index2, uintC index3)
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{
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var cl_I exponent;
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{
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var uintC exp_len = index2-index4; // Anzahl Stellen des Exponenten
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if (exp_len > 0) {
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var const char * ptr = &string[index4]; // zeigt auf den Exponentmarker
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ptr++; exp_len--; // Exponentmarker überlesen
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var cl_signean exp_sign = 0; // Exponenten-Vorzeichen
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switch (*ptr) {
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case '-': exp_sign = ~exp_sign; // Vorzeichen := negativ
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case '+': ptr++; exp_len--; // Exponenten-Vorzeichen überlesen
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default: ;
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}
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exponent = digits_to_I(ptr,exp_len,(uintD)base); // Exponent in Integer umwandeln
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if (!(exp_sign==0))
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exponent = -exponent; // incl. Vorzeichen
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} else {
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// kein Exponent da
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exponent = 0;
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}
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}
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// exponent = Exponent als Integer.
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var cl_RA base_power = expt(base,exponent-(index4-index3)); // zu multiplizierende Zehnerpotenz
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var cl_I mantisse = // Mantisse als Integer
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digits_to_I(&string[index1],index4-index1,(uintD)base);
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// Mantisse (Integer) und Zehnerpotenz (rational >0) unelegant zusammenmultiplizieren:
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var cl_RA ratvalue;
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if (integerp(base_power)) {
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DeclareType(cl_I,base_power);
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ratvalue = mantisse * base_power;
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} else {
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// falls mantisse/=0, in exponent=1/10^i den Zähler durch mantisse
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// ersetzen (liefert ungekürzten Bruch, Vorsicht!)
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DeclareType(cl_RT,base_power);
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if (zerop(mantisse))
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ratvalue = 0;
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else {
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ASSERT(TheRatio(base_power)->refcount == 1);
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TheRatio(base_power)->numerator = mantisse;
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ratvalue = base_power;
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}
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}
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// ratvalue = Mantisse * Zehnerpotenz, als ungekürzte rationale Zahl!
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floatformatcase(prec
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, // in Short-Float umwandeln
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{
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var cl_SF x = cl_RA_to_SF(ratvalue);
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if (sign==0) { return x; } else { return -x; }
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}
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, // in Single-Float umwandeln
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{
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var cl_FF x = cl_RA_to_FF(ratvalue);
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if (sign==0) { return x; } else { return -x; }
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}
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, // in Double-Float umwandeln
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{
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var cl_DF x = cl_RA_to_DF(ratvalue);
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if (sign==0) { return x; } else { return -x; }
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}
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, // in Long-Float umwandeln
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{
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var cl_LF x = cl_RA_to_LF(ratvalue,len);
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if (sign==0) { return x; } else { return -x; }
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}
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);
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}
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} // namespace cln
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