80 lines
1.6 KiB
C
80 lines
1.6 KiB
C
/* ldexp.c - ldexp math routine */
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/* Copyright 1992-1993 Wind River Systems, Inc. */
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/*
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modification history
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--------------------
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01h,05feb99,dgp document errno values
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01g,05feb93,jdi doc changes based on kdl review.
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01f,02dec92,jdi doc tweaks.
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01e,28oct92,jdi documentation cleanup.
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01d,21sep92,smb replaced original version.
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01c,20sep92,smb documentation additions
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01b,30jul92,kdl replaced routine contents with ldexp() from floatLib.c.
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01a,08jul92,smb written, documentation.
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*/
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/*
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DESCRIPTION
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SEE ALSO: American National Standard X3.159-1989
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NOMANUAL
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*/
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#include "math.h"
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#include "stddef.h"
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#include "errno.h"
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#include "private/mathP.h"
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/*******************************************************************************
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*
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* ldexp - multiply a number by an integral power of 2 (ANSI)
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*
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* This routine multiplies a floating-point number by an integral power of 2.
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* A range error may occur.
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*
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* INCLUDE FILES: math.h
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*
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* RETURNS: The double-precision value of <v> times 2 to the power of <xexp>.
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*
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* ERRNO: EDOM, ERANGE
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*
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*/
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double ldexp
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(
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double v, /* a floating point number */
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int xexp /* exponent */
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)
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{
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double zero = 0.0;
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switch (fpTypeGet (v, NULL))
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{
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case NAN: /* NOT A NUMBER */
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errno = EDOM;
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break;
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case INF: /* INFINITE */
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errno = ERANGE;
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break;
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case ZERO: /* ZERO */
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return (zero);
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default:
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if (xexp >= 0)
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for(; (xexp > 0); xexp--, v *= 2.0);
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else
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for(; (xexp < 0); xexp++, v /= 2.0);
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return (v);
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}
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return (zero);
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}
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