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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4349 | Serge | 1 | /* sf_scalbn.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 | #include "fdlibm.h" |
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| 17 | #include |
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| 18 | #include |
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| 19 | |||
| 20 | #if INT_MAX > 50000 |
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| 21 | #define OVERFLOW_INT 50000 |
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| 22 | #else |
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| 23 | #define OVERFLOW_INT 30000 |
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| 24 | #endif |
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| 25 | |||
| 26 | #ifdef __STDC__ |
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| 27 | static const float |
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| 28 | #else |
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| 29 | static float |
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| 30 | #endif |
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| 31 | two25 = 3.355443200e+07, /* 0x4c000000 */ |
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| 32 | twom25 = 2.9802322388e-08, /* 0x33000000 */ |
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| 33 | huge = 1.0e+30, |
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| 34 | tiny = 1.0e-30; |
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| 35 | |||
| 36 | #ifdef __STDC__ |
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| 37 | float scalbnf (float x, int n) |
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| 38 | #else |
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| 39 | float scalbnf (x,n) |
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| 40 | float x; int n; |
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| 41 | #endif |
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| 42 | { |
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| 43 | __int32_t k,ix; |
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| 44 | __uint32_t hx; |
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| 45 | |||
| 46 | GET_FLOAT_WORD(ix,x); |
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| 47 | hx = ix&0x7fffffff; |
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| 48 | k = hx>>23; /* extract exponent */ |
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| 49 | if (FLT_UWORD_IS_ZERO(hx)) |
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| 50 | return x; |
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| 51 | if (!FLT_UWORD_IS_FINITE(hx)) |
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| 52 | return x+x; /* NaN or Inf */ |
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| 53 | if (FLT_UWORD_IS_SUBNORMAL(hx)) { |
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| 54 | x *= two25; |
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| 55 | GET_FLOAT_WORD(ix,x); |
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| 56 | k = ((ix&0x7f800000)>>23) - 25; |
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| 57 | if (n< -50000) return tiny*x; /*underflow*/ |
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| 58 | } |
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| 59 | k = k+n; |
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| 60 | if (k > FLT_LARGEST_EXP) return huge*copysignf(huge,x); /* overflow */ |
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| 61 | if (k > 0) /* normal result */ |
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| 62 | {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;} |
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| 63 | if (k < FLT_SMALLEST_EXP) { |
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| 64 | if (n > OVERFLOW_INT) /* in case integer overflow in n+k */ |
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| 65 | return huge*copysignf(huge,x); /*overflow*/ |
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| 66 | else return tiny*copysignf(tiny,x); /*underflow*/ |
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| 67 | } |
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| 68 | k += 25; /* subnormal result */ |
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| 69 | SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); |
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| 70 | return x*twom25; |
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| 71 | } |
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| 72 | |||
| 73 | #ifdef _DOUBLE_IS_32BITS |
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| 74 | |||
| 75 | #ifdef __STDC__ |
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| 76 | double scalbn(double x, int n) |
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| 77 | #else |
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| 78 | double scalbn(x,n) |
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| 79 | double x; |
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| 80 | int n; |
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| 81 | #endif |
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| 82 | { |
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| 83 | return (double) scalbnf((float) x, n); |
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| 84 | } |
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| 85 | |||
| 86 | #endif /* defined(_DOUBLE_IS_32BITS) */ |