81 lines
1.4 KiB
C
81 lines
1.4 KiB
C
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/* @(#)z_ldexpf.c 1.0 98/08/13 */
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/******************************************************************
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* ldexp
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*
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* Input:
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* d - a floating point value
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* e - an exponent value
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*
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* Output:
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* A floating point value f such that f = d * 2 ^ e.
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*
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* Description:
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* This function creates a floating point number f such that
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* f = d * 2 ^ e.
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*
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*****************************************************************/
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#include <float.h>
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#include "fdlibm.h"
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#include "zmath.h"
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#define FLOAT_EXP_OFFS 127
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float
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ldexpf (float d,
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int e)
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{
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int exp;
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__int32_t wd;
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GET_FLOAT_WORD (wd, d);
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/* Check for special values and then scale d by e. */
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switch (numtestf (wd))
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{
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case NAN:
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errno = EDOM;
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break;
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case INF:
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errno = ERANGE;
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break;
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case 0:
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break;
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default:
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exp = (wd & 0x7f800000) >> 23;
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exp += e;
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if (exp > FLT_MAX_EXP + FLOAT_EXP_OFFS)
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{
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errno = ERANGE;
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d = z_infinity_f.f;
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}
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else if (exp < FLT_MIN_EXP + FLOAT_EXP_OFFS)
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{
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errno = ERANGE;
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d = -z_infinity_f.f;
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}
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else
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{
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wd &= 0x807fffff;
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wd |= exp << 23;
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SET_FLOAT_WORD (d, wd);
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}
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}
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return (d);
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}
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#ifdef _DOUBLE_IS_32BITS
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double ldexp (double x, int e)
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{
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return (double) ldexpf ((float) x, e);
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */
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