mirror of
https://github.com/fluencelabs/musl
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55 lines
1.6 KiB
C
55 lines
1.6 KiB
C
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/* origin: FreeBSD /usr/src/lib/msun/src/s_scalbnf.c */
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/*
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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#include "libm.h"
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static const float
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two25 = 3.355443200e+07, /* 0x4c000000 */
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twom25 = 2.9802322388e-08, /* 0x33000000 */
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huge = 1.0e+30,
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tiny = 1.0e-30;
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float scalbnf(float x, int n)
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{
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int32_t k, ix;
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GET_FLOAT_WORD(ix, x);
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k = (ix&0x7f800000)>>23; /* extract exponent */
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if (k == 0) { /* 0 or subnormal x */
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if ((ix&0x7fffffff) == 0) /* +-0 */
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return x;
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x *= two25;
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GET_FLOAT_WORD(ix, x);
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k = ((ix&0x7f800000)>>23) - 25;
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if (n < -50000)
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return tiny*x; /*underflow*/
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}
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if (k == 0xff) /* NaN or Inf */
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return x + x;
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k = k + n;
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if (k > 0xfe)
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return huge*copysignf(huge, x); /* overflow */
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if (k > 0) { /* normal result */
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SET_FLOAT_WORD(x, (ix&0x807fffff)|(k<<23));
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return x;
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}
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if (k <= -25)
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if (n > 50000) /* in case integer overflow in n+k */
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return huge*copysignf(huge,x); /*overflow*/
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return tiny*copysignf(tiny, x); /*underflow*/
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k += 25; /* subnormal result */
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SET_FLOAT_WORD(x, (ix&0x807fffff)|(k<<23));
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return x*twom25;
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}
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