30 lines
822 B
C
30 lines
822 B
C
/*
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* modf(value, iptr) returns the signed fractional part of value
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* and stores the integer part indirectly through iptr.
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*
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*/
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#include <nan.h>
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#include <values.h>
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double
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modf(value, iptr)
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double value; /* don't declare register, because of KILLNaN! */
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register double *iptr;
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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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if ((absvalue = (value >= 0.0) ? value : -value) >= MAXPOWTWO)
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*iptr = value; /* it must be an integer */
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else {
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*iptr = absvalue + MAXPOWTWO; /* shift fraction off right */
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*iptr -= MAXPOWTWO; /* shift back without fraction */
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while (*iptr > absvalue) /* above arithmetic might round */
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*iptr -= 1.0; /* test again just to be sure */
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if (value < 0.0)
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*iptr = -*iptr;
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}
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return (value - *iptr); /* signed fractional part */
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}
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