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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 2 | pj | 1 | /* s_scalbnf.c -- float version of s_scalbn.c. |
| 2 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
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| 3 | */ |
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| 4 | |||
| 5 | /* |
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| 6 | * ==================================================== |
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| 7 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 8 | * |
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| 9 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 10 | * Permission to use, copy, modify, and distribute this |
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| 11 | * software is freely granted, provided that this notice |
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| 12 | * is preserved. |
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| 13 | * ==================================================== |
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| 14 | */ |
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| 15 | |||
| 16 | #ifndef lint |
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| 17 | static char rcsid[] = "$\Id: s_scalbnf.c,v 1.2 1995/05/30 05:50:24 rgrimes Exp $"; |
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| 18 | #endif |
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| 19 | |||
| 20 | #include "math.h" |
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| 21 | #include "math_private.h" |
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| 22 | |||
| 23 | #ifdef __STDC__ |
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| 24 | static const float |
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| 25 | #else |
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| 26 | static float |
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| 27 | #endif |
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| 28 | two25 = 3.355443200e+07, /* 0x4c000000 */ |
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| 29 | twom25 = 2.9802322388e-08, /* 0x33000000 */ |
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| 30 | huge = 1.0e+30, |
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| 31 | tiny = 1.0e-30; |
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| 32 | |||
| 33 | #ifdef __STDC__ |
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| 34 | float scalbnf (float x, int n) |
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| 35 | #else |
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| 36 | float scalbn (x,n) |
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| 37 | float x; int n; |
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| 38 | #endif |
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| 39 | { |
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| 40 | int32_t k,ix; |
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| 41 | GET_FLOAT_WORD(ix,x); |
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| 42 | k = (ix&0x7f800000)>>23; /* extract exponent */ |
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| 43 | if (k==0) { /* 0 or subnormal x */ |
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| 44 | if ((ix&0x7fffffff)==0) return x; /* +-0 */ |
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| 45 | x *= two25; |
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| 46 | GET_FLOAT_WORD(ix,x); |
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| 47 | k = ((ix&0x7f800000)>>23) - 25; |
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| 48 | if (n< -50000) return tiny*x; /*underflow*/ |
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| 49 | } |
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| 50 | if (k==0xff) return x+x; /* NaN or Inf */ |
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| 51 | k = k+n; |
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| 52 | if (k > 0xfe) return huge*copysignf(huge,x); /* overflow */ |
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| 53 | if (k > 0) /* normal result */ |
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| 54 | {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;} |
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| 55 | if (k <= -25) |
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| 56 | if (n > 50000) /* in case integer overflow in n+k */ |
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| 57 | return huge*copysignf(huge,x); /*overflow*/ |
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| 58 | else return tiny*copysignf(tiny,x); /*underflow*/ |
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| 59 | k += 25; /* subnormal result */ |
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| 60 | SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); |
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| 61 | return x*twom25; |
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| 62 | } |