28 lines
679 B
C
28 lines
679 B
C
/*
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* frexp(value, eptr)
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* returns a double x such that x = 0 or 0.5 <= |x| < 1.0
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* and stores an integer n such that value = x * 2 ** n
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* indirectly through eptr.
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*
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*/
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#include <nan.h>
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double
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frexp(value, eptr)
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double value; /* don't declare register, because of KILLNan! */
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register int *eptr;
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{
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register double absvalue;
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KILLNaN(value); /* raise exception on Not-a-Number (3b only) */
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*eptr = 0;
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if (value == 0.0) /* nothing to do for zero */
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return (value);
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absvalue = (value > 0.0) ? value : -value;
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for ( ; absvalue >= 1.0; absvalue *= 0.5)
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++*eptr;
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for ( ; absvalue < 0.5; absvalue += absvalue)
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--*eptr;
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return (value > 0.0 ? absvalue : -absvalue);
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}
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