| 1 | /* sf_scalbn.c -- float version of s_scalbn.c. |
|---|
| 2 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
|---|
| 3 | */ |
|---|
| 4 | |
|---|
| 5 | /* |
|---|
| 6 | * ==================================================== |
|---|
| 7 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
|---|
| 8 | * |
|---|
| 9 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
|---|
| 10 | * Permission to use, copy, modify, and distribute this |
|---|
| 11 | * software is freely granted, provided that this notice |
|---|
| 12 | * is preserved. |
|---|
| 13 | * ==================================================== |
|---|
| 14 | */ |
|---|
| 15 | |
|---|
| 16 | #include "fdlibm.h" |
|---|
| 17 | #include <limits.h> |
|---|
| 18 | #include <float.h> |
|---|
| 19 | |
|---|
| 20 | #if INT_MAX > 50000 |
|---|
| 21 | #define OVERFLOW_INT 50000 |
|---|
| 22 | #else |
|---|
| 23 | #define OVERFLOW_INT 30000 |
|---|
| 24 | #endif |
|---|
| 25 | |
|---|
| 26 | #ifdef __STDC__ |
|---|
| 27 | static const float |
|---|
| 28 | #else |
|---|
| 29 | static float |
|---|
| 30 | #endif |
|---|
| 31 | two25 = 3.355443200e+07, /* 0x4c000000 */ |
|---|
| 32 | twom25 = 2.9802322388e-08, /* 0x33000000 */ |
|---|
| 33 | huge = 1.0e+30, |
|---|
| 34 | tiny = 1.0e-30; |
|---|
| 35 | |
|---|
| 36 | #ifdef __STDC__ |
|---|
| 37 | float scalbnf (float x, int n) |
|---|
| 38 | #else |
|---|
| 39 | float scalbnf (x,n) |
|---|
| 40 | float x; int n; |
|---|
| 41 | #endif |
|---|
| 42 | { |
|---|
| 43 | __int32_t k,ix; |
|---|
| 44 | __uint32_t hx; |
|---|
| 45 | |
|---|
| 46 | GET_FLOAT_WORD(ix,x); |
|---|
| 47 | hx = ix&0x7fffffff; |
|---|
| 48 | k = hx>>23; /* extract exponent */ |
|---|
| 49 | if (FLT_UWORD_IS_ZERO(hx)) |
|---|
| 50 | return x; |
|---|
| 51 | if (!FLT_UWORD_IS_FINITE(hx)) |
|---|
| 52 | return x+x; /* NaN or Inf */ |
|---|
| 53 | if (FLT_UWORD_IS_SUBNORMAL(hx)) { |
|---|
| 54 | x *= two25; |
|---|
| 55 | GET_FLOAT_WORD(ix,x); |
|---|
| 56 | k = ((ix&0x7f800000)>>23) - 25; |
|---|
| 57 | if (n< -50000) return tiny*x; /*underflow*/ |
|---|
| 58 | } |
|---|
| 59 | k = k+n; |
|---|
| 60 | if (k > FLT_LARGEST_EXP) return huge*copysignf(huge,x); /* overflow */ |
|---|
| 61 | if (k > 0) /* normal result */ |
|---|
| 62 | {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;} |
|---|
| 63 | if (k < FLT_SMALLEST_EXP) { |
|---|
| 64 | if (n > OVERFLOW_INT) /* in case integer overflow in n+k */ |
|---|
| 65 | return huge*copysignf(huge,x); /*overflow*/ |
|---|
| 66 | else return tiny*copysignf(tiny,x); /*underflow*/ |
|---|
| 67 | } |
|---|
| 68 | k += 25; /* subnormal result */ |
|---|
| 69 | SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); |
|---|
| 70 | return x*twom25; |
|---|
| 71 | } |
|---|
| 72 | |
|---|
| 73 | #ifdef _DOUBLE_IS_32BITS |
|---|
| 74 | |
|---|
| 75 | #ifdef __STDC__ |
|---|
| 76 | double scalbn(double x, int n) |
|---|
| 77 | #else |
|---|
| 78 | double scalbn(x,n) |
|---|
| 79 | double x; |
|---|
| 80 | int n; |
|---|
| 81 | #endif |
|---|
| 82 | { |
|---|
| 83 | return (double) scalbnf((float) x, n); |
|---|
| 84 | } |
|---|
| 85 | |
|---|
| 86 | #endif /* defined(_DOUBLE_IS_32BITS) */ |
|---|
